First General Report on the Coal Deposits of New Zealand

James Hector

First published by George Didsbury, Govt. Printer in 1866

Digitised and made available online by the University of Auckland Libraries and Learning Services.

Epub © 2013 Early New Zealand Books Collection

ISBN 978-1-927288-72-6

[TITLE PAGE]

Geological Survey of New Zealand.

FIRST

GENERAL REPORT

ON THE

COAL DEPOSITS

OF

NEW ZEALAND:

BY

JAMES HECTOR, M.D., F.R.S.
DIRECTOR.

PUBLISHED BY COMMAND.

NEW ZEALAND:
By Authority: GEORGE DIDSBURY, Government Printer, Wellington.

1866.

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[PREFACE]

PREFACE.

THE following Report on the COAL DEPOSITS OF NEW ZEALAND has been prepared at the desire of the Colonial Office in a manner uniform with reports of a similar nature which have already been laid before the British Parliament.

A great deal of information which would have local interest has therefore been omitted, especially such details as relate to the history of the discovery of the various coal mines and to minute descriptions of local features which could only have been given by quotations from reports already published.

As, however, it has been considered desirable to publish this report in the Colony, it is necessary in doing so to indicate for the New Zealand reader, the principal special reports in which fuller information respecting the coal deposits will be found. It may be mentioned that as they are scattered throughout a variety of Gazettes and other official publications which are difficult to obtain, it is intended to reprint extracts from these reports in a better form for preservation, and uniform with other publications of the Geological Department.

J. H.

Wellington, N.Z., October, 1866.

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LIST OF PRINCIPAL SPECIAL REPORTS

ON

THE COAL DEPOSITS OF NEW ZEALAND,

WHICH HAVE APPEARED IN GOVERNMENT GAZETTES, ETC.

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COAL DEPOSITS OF NEW ZEALAND

COAL DEPOSITS OF NEW ZEALAND:

THEIR NATURE AND CLASSIFICATION.

IN New Zealand no coal seams have yet been discovered that can be referred to Paleozoic coal measures, such as occur in the Northern Hemisphere, as all the formations which contain workable seams belong to the Secondary or Mesozoic, and to the Tertiary or Cainozoic epochs.

The quality of the coal found in New Zealand is, at the same time, extremely varied, some of it being for all practical purposes equal, if not superior, to much of the coal used in other parts of the world, while on the other hand, a great deal is of a comparatively inferior description, though it still has a great local value as fuel in the districts where it occurs.

At first it was attempted to class these various qualities of coal according to their respective geological ages, but though this may be effected when the geology of the country is better understood in detail, the evidence on which we must rely for such a classification is as yet contradictory. It has, therefore, been considered more advisable in the present state of our knowledge to adopt a provisional classification founded on the chemical composition of the coals.

The amount of water chemically combined with the coal being not only the best theoretical indication of its value, especially if the proportion of inorganic matter or ash be deducted in making the calculation, but also the most important point in considering its practical value as fuel, it is proposed to divide the coals found in New Zealand into two groups, under the terms Hydrous and Anhydrous coal, or, those which still contain a large percentage of water chemically combined with them, and those which we may assume to have been deprived of that water by a chemical change, which, in some cases, may have been induced by causes operating feebly throughout lengthened periods, or, in others, has been rapidly effected on more modern deposits of carbon, under circumstances which favoured a more energetic action.

In the following table an abstract is given of the average results of about seventy chemical analyses which have been made in the Laboratory of the Geological Survey, by which the respective characters of each group of New Zealand coals can be compared with that of Australian and English coals.

ABSTRACT showing AVERAGE COMPOSITION of the COAL of New Zealand, as compared with Australian and English Coal; from analyses made in the Laboratory of the N.Z. Geological Survey.

I. – HYDROUS COALS.

These in quality correspond with the Brown Coals so extensively mined on the continent of Europe, and, fortunately for many of the districts of New Zealand, where firewood is deficient, they are very largely distributed throughout both Islands.

A point worthy of remark is, that whereas in Europe the deposits of Brown Coal (or Lignite as it is usually termed) occur generally in local beds of immense thickness, but confined to limited areas, those of New Zealand form regular seams of moderate thickness, and associated with alternating beds of clay, shale, and sandstone, somewhat as with the older coal formations.

The Brown Coal formation of New Zealand is, moreover, frequently involved in dislocations and disturbances of the underlying rocks, a circumstance which has no doubt given rise to a great variety in the value of the coal seams as fuel.

As a rule the Hydrous coal measures lie on the eastern slopes of the axial rocks in both Islands, whereas the Anhydrous coal fields are found either west of lines of dislocation, or having a prevailing westerly dip.

This apparent coincidence, which may prove of great practical use in tracing these deposits, requires further investigation however before we assume that the position of the coal, relative to the line of dislocation, has any necessary bearing on its quality.

The Hydrous coal is of a brown colour, but hard and glossy, and frequently contains a quantity of fossil resin, which greatly facilitates its combustion.

Its principal defect is its bulk in proportion to its weight, and its tendency to crack and break into small fragments by desiccation on exposure to the atmosphere, although in this manner it loses only a small proportion of the total quantity of the water which enters into its composition, and which gives to it the character of Hydrous coal.

The remainder of the water, usually from 12 to 20 per cent., can only be expelled by raising the temperature very considerably, and much of the heat derived from the combustion of the coal is thus absorbed.

Nevertheless, it is a most valuable fuel, and is largely used both for domestic purposes and for raising steam.

It is also highly applicable to the manufacture of bricks and pottery, and for other economic purposes.

The best known deposits of this coal in the North Island are those mined at Drury, twenty miles to the south of the City of Auckland, and at various points in the extensive and fertile valley of the Waikato River, where they will have a great local value in connection with the facilities for internal steam navigation which that river affords.

Seams of this coal, varying from six to fifteen feet in thickness, occur at intervals over a large area of country, so as to lead to the conclusion that the formation is very extensive.

Prom the existence of seams of this coal on the Mokau River, north of Taranaki, and on most of the tributaries of the Wanganui River, it is probable that another extensive Brown Coal field exists in this portion of the Island, while there are also indications of a third extension of this same formation on the East Coast.

Our geological knowledge of these districts is as yet too limited to allow of an approximate estimate being made of the extent and total thickness of these Hydrous Brown Coal deposits in the North Island; but there can be no doubt that they underlie an area of at least several hundred square miles in extent.

In the South Island, the best known and most important deposit of the Hydrous Brown Coal formation is that on the south-east Coast, northward from the Molyneux River, where it extends continuously over at least forty-five square miles, forming hills 500 to 1000 feet in height, broken into sharp ridges by the outcropping beds of grit and conglomerate. In this formation there are several seams of good coal varying from six to twenty feet in thickness, their aggregate thickness in a section three miles in length, exposed on the sea-shore, amounting to 56 feet.

The total quantity of coal in this district has been estimated at 100,000,000 tons. Two large mines have been opened in this coal field.

The Clutha Mine is on the sea coast, about three miles from the mouth of the Clutha River, and three quarters of a mile from a bend of the river where vessels can lie alongside a wharf and load in safety at all times, and to which point the coal is brought by an iron tramway.

It is, however, impossible to effect a regular shipment of coal from this place to the market, owing to the risks encountered at the entrance to the river, where the navigation is exceedingly difficult.

The principal consumption of this coal has therefore been for

local use, and for the steam navigation of the river; but as it is proposed to construct a railway from Dunedin to the Clutha Valley, a distance of sixty miles, this valuable fuel will be brought into more general use than at present.

The only other mine of importance opened in this coal field is in the vicinity of Tokomairiro. The coal is very similar to that obtained from the Clutha mine, and there is no reason to doubt that the same formation, if not the same seam, continues between the two places, which are about fourteen miles apart.

The seam is nine feet thick, and is worked by a level drive in the side of a hill.

The present access to the mine is very bad, but a very small expenditure would construct a tramway for six miles to the township of Tokomairiro, which is the centre of a populous and important district that will be passed through by the proposed railway.

The Green Island and Saddle Hill Basin, which is within six miles of Dunedin, and about five or six square miles in extent, is another important development of this same coal formation.

Two of the principal seams, seven and nine feet in thickness, are worked at four different collieries, and though the quality is slightly inferior to that of the Clutha coal, yet, owing to the proximity to Dunedin, its consumption is very considerable; and it would, there is no doubt, be more universally used were it not for the great expense of cartage.

In 1864 the quantity produced from the mines in this district was about 4000 tons.

A third great extent of this formation on the eastern seaboard of the Province of Otago underlies the level country to the eastward of the Kakanui Mountains, and is in all probability the southern extremity of a formation that will be found to underlie the tertiary rocks that form the higher portions of the great Canterbury plains.

Coal of the description under consideration is also very extensively distributed throughout the interior of the Province of Otago, as local deposits in hollows of the surface of the older formations.

Such deposits, though generally of inferior quality to those above mentioned, have great local value, and are essential to the working of the gold fields on which there is a great deficiency of timber.

Pits have been opened in the vicinity of the principal gold diggings, and in some cases round the margins of the larger interior basins, the strata display a regularity and thickness that leads to the belief that they are of very considerable extent and will yield a steady supply.

From the number of localities in the Province of Southland where this coal is excavated for local use, its extensive development in the Northern District, and indeed over the greater part of that Province, is extremely probable.

Some of the coal from the district in question is of very superior quality, and occurs in seams eight to twelve feet thick.

There are many other localities in New Zealand besides those already alluded to where valuable seams of Hydrous coal occur, but the above information is sufficient to show the singular importance of these deposits to the future development of the Colony, as, from their wide distribution and the applicability of this description of coal to most uses of mineral fuel – when compactness and economy of space is not the first consideration – the necessity for importing coal from other districts for local purposes will be obviated.

II. – ANHYDROUS COALS.

Under this group have been classed all the coal found in New Zealand, which resembles in quality the coal imported from England and Australia, which at the present time is the only fuel used in this Colony for the purpose of steam navigation.

Owing to the great and still progressive development of the steam coastal service in New Zealand, which in a great measure replaces the expensive works for internal communication, necessary in countries not favoured with so extensive a sea-board, it is very important to the future prosperity of the Colony that it should be independent of other countries for its supplies of steam coal. Already, with a population of two hundred thousand inhabitants, the sum of £160,000 is withdrawn from the Colony every year for this item, and spent principally in labour in a neighboring Colony, and for shipping expenses, neither of which are reproductive to New Zealand.

It is, therefore, satisfactory to find that coal exists in New Zealand adapted for the use of steam vessels on long sea voyages, and moreover that the supply is abundant, and occurs under circumstances that will ultimately admit of its being profitably worked, although there may be some difficulties, and, perhaps failures, in the first attempts.

The composition of the coal comprised in this group is very varied, but not more than is usual among coal seams from different coal fields in other countries,

The only point in which, as a class, they are deficient in any

of the characters which have been laid down as requisite for a perfect steam coal 1 is in the solidity and toughness that enables the coal to withstand the constant attrition it must experience from the motion of the vessel. The consequence of this defect would be the formation of dross, the combustion of which is difficult without the use of close furnace bars, which greatly impair the draught.

This defect is, however, comparatively insignificant, and is more than compensated for (except in a few instances) by the purity of the coal, its tendency to cake, and the facility with which complete combustion can be effected, so that the loss by the formation of cinders will be much below the average.

Full particulars respecting the composition of the different varieties of Anhydrous coal are given in the Appendix to this Report, part of which has already been printed in the Supplement to the Jurors' Reports on the New Zealand Exhibition, 1865.

The most important development of the coal seams of this class is on the West Coast of the South Island, where the formation occurs resting on the surface of the metamorphic and crystalline rocks.

At Preservation Inlet, in the Province of Otago, and at various other points on the coast, this formation occurs, but without any valuable seams of coal, so far as we yet know, until the Grey River is reached; the coast to the south being principally formed either of the older rocks or of sub-alpine drifts and alluvium.

Prom the Grey to Cape Farewell this coal has been discovered at intervals, but whether or not the seams at these different localities are portions of the same formation, partially isolated by denudation, has not yet been determined.

The following information respecting the coal fields at the Grey River has been furnished by Dr. Haast.

At this locality the coal extends over an area which he has estimated at fifteen miles in length by six in width.

The coal seams are said to rise with a dip of from ten to thirty degrees from the sea level to an altitude of several thousand feet, so that they occur under circumstances most favourable for their being worked at a small cost, as neither shafts nor pumping machinery will be necessary.

There is no apparent disturbance of the beds, nor any reason to

suppose that the whole of the coal in the above area may not be worked.

The number of workable seams that have been discovered is four, the main seam being fifteen feet three inches in thickness.

Only one mine has yet been opened up in this field on the north side of the River Grey, at seven miles from its mouth. It is a simple chamber opened in the fifteen feet seam, at ten feet above flood mark.

From this point the coal is supposed to extend on the rise for about four miles, in an easterly direction, the dip in the present mine being ten degrees to the west.

Arrangements are now being made for working the coal on the south side of the river, which is in the Province of Canterbury, and for the construction of a railway to convey it to a point on the river where it can be shipped in vessels of six to seven feet draught.

At the present time the great obstacle to the development of these coal mines is the high price of labour, owing to the attractions offered by the gold fields, but when this excitement has subsided a large portion of the present population of that district, which is estimated at fifteen thousand persons, will doubtless become permanent, and notwithstanding the present temporary check, the importance of these coal fields will be much sooner established than if the auriferous deposits had not been discovered, and the "Westland District had still remained as inaccessible as it was twelve months ago.

At present the output from the coal mine is about 250 to 300 tons per week, and is taken down the river in canoes and in 16 ton barges and delivered alongside the vessels at 40s. per ton. It has been used to a large extent on board the steam vessels that frequent the coast, and gives great satisfaction. A small quantity of this coal is also reported to have been tried in the Dunedin Gas Works, and to have yielded a large quantity, of illuminating gas.

Regarding the coal fields at the Buller River, detailed information may be found in the reports of Dr. Haast and Messrs. Rochford, Burnett, and Blackett.

The only outcrops of coal known in this district occur at altitudes of more than 1500 feet above the sea level, the strata resting upon a high narrow plateau that lies parallel with the coast, and extends though possibly not continuously, as far north as West Wanganui, a distance of eighty miles, where its outcrop again reaches the sea level as at the Grey.

In the immediate neighbourhood of the Buller River the existence of workable coal seams is considered certain over an area of at least fifteen square miles.

Reckoning none of the seams having a less thickness than five feet, there is a total of thirty-eight feet of pure coal; and the quantity available in this one locality has been estimated at 200,000,000 tons.

Although the Buller Harbour is on the whole more favourable for shipping than the Grey, yet the greater expense of working the coal, on account of the altitude and distance from the shipping place at which the seams occur, would indicate the Grey coal field to be the most immediately available. The quality of the coal is practically identical from both localities, and is characterized among all other New Zealand coals by the small percentage of water which it contains, usually from 1 to 2 per cent. It also contains less than the usual amount of impurity, about 90 per cent of the coal being combustible, 30 to 35 per cent. of which is gaseous matter, leaving 65 per cent. of lustrous metallic coke, which possesses intense heating qualities.

As steam coal, its value has been fully established by a series of experiments made in 1865 with the trial boiler at Woolwich Dockyard. 2

The results given by Mr. Trickett, chief engineer of the dockyard, are extremely favourable to the Buller and Grey coal, even as compared with the Welsh and North of England coal; and he appends the following remarks to the tabulated results of his experiments: –

"The Grey coal cakes in burning, and makes a hollow fire forming a small quantity of light clinker that does not adhere to the bars. Light ash only falls through the fire-bars, and a considerable quantity of white ash passes up the chimney, leaving a dark grey sandy kind of dust in the tubes and fire-box. The smoke is small in quantity, and the coal is tender and likely to break small in being moved from ship to ship."

"The Buller coal is a more open burning coal, and does not cake 3 forming a rather closer clinker than the other; and leaves a sooty deposit in the tubes and fire-box, more like the Hartly (North of England) coal, and gives off a black smoke."

"No stoking tool was used in burning the samples of both kinds of coal, and nothing seems to be required, beyond throwing the coal

on to the fires; and the quantity of each clinker is not greater than that of the North of England coal. The evaporative power of this coal is about the average of that of North of England coal as supplied to the service; but it is not quite so rapid, and requires a rather longer time to boil off a given quantity of water. The trial of the 17th November was made with the bars half-inch apart, the other trials with the bars about three-eighths of an inch apart."

And again Mr. Trickett writes: –

"I beg to report that additional trials have been made of the New Zealand coal, and a comparative statement is forwarded herewith. The mean result of ten trials of North Country coal and ten trials of Welsh coal at the same boiler are given for comparison, from which it will be seen that the New Zealand coal evaporates more water per pound of coal than the North of England or Welsh, but does not evaporate it so rapidly; or in other words a larger fire-grate is required in the same boiler to evaporate a given quantity of water per hour with New Zealand coal than would be required if North of England or Welsh coal were used."

In communicating this Report to the Nelson Government, Mr. Burnett has constructed four tables, showing the results obtained, in a condensed and simple form, and also giving for comparison a summary of the results of similar experiments performed also at Woolwich Dockyard, but on a previous occasion, upon New South Wales coal.

Only the second of Mr. Burnett's tables and his remarks are here quoted, as they are sufficient to show the relative value of the different coals experimented on.

TABLE snowing the RELATIVE VALUE for Steam purposes of North of England, Welsh, New South Wales, and Grey and Buller Coal, calculated on the basis given by the trials of these Coals at Woolwich Dockyard, viz.: – If 100 lbs. of average North of England Coal will evaporate a given quantity of water in an hour, this Table shows how the same work can be done by the other Coals.

EXAMPLE OF CALCULATION – BULLER.

The following remarks are by Mr. Burnett, on the Woolwich Reports of trials of Grey and Buller Coal, and the Tables calculated from these Reports, showing their relative value as compared with North of England, Welsh, and New South Wales Coal: –

"The samples of coal, both from the Grey and Buller, were taken from within a few feet of the outcrop, and almost close to the surface, and it is only fair to conclude (as indeed the recent working at the Grey has demonstrated) that the quality of the coal will improve as the works are continued further from the outcrop, and deeper below the surface.

"It is to be presumed that the North of England, Welsh, and New South Wales (being from actual working mines), would be a fair average of the mineral in its full perfection; and in the case of the two former, probably fresh from the mines, whereas that from the Grey and Buller was mere outcrop coal, not tested for more than sixteen months after it was worked, and after being broken and deteriorated by shipping, re-shipping, carting, packing, and conveying to the other side of the world; so it is only reasonable to conclude that samples of these coals, a moderate depth from the surface (such as will be produced when the mines are actually worked), tested under equally favourable circumstances, would contrast still better than they do at present.

"When the Grey and Buller coal was packed in boxes at Nelson, the dead small was taken out and put in bags, but was not intended to be sent to England; however, by mistake it was sent, and to this accident we are indebted for one of the most valuable results of these trials, viz., that the 'coal in bags' (see second Report), i.e. the dead small, is very nearly equal to any other part of the coal.

"This is a most important quality, as it does away with the necessity of screening, by which a considerable percentage of other coal is wasted: the small of Welsh coal particularly is almost useless.

"Another very valuable property is the small quantity of clinker and ash contained in this coal; and what little clinker there is does not stick to the bars. The amount of disagreeable labour saved by this can only be thoroughly appreciated by the working stoker. Indeed, it appears that no stoking whatever is required, 'but that a small increase of the water evaporated per hour is obtained when the fires are stoked.'

"This is shown very clearly in table No. IV., second part, where, in the trials of dead small, 6.11 per cent. more water is evaporated in a given time when the fires are stoked; so, it may be presumed, that had the coal in boxes been stoked, the result would nave been better in like proportion.

"Table No. IV. is a condensation of the information contained in the reports and tables, and shows, at a glance the comparative value of each kind of coal tested.

"It is interesting to compare the results of minute and elaborate trials at Woolwich, with the trials of the same coal on board local steamers in 1861, (published in the New Zealand Gazette, February 15, 1862,) for it will be seen that in almost every respect they agree exactly.

"There was only one trial of Buller coal, as only two tons were

sent to England, owing to the difficulty of carrying it from the mine to the port without roads; but it will be seen that even this one trial shows a result almost equal to the best, as it is only 1 per cent. below Welch coal in evaporating water in a given time. (See table No. IV., second part.)

"It is rather singular that Mr. Trickett in his report says, 'the Buller coal does not cake,' whereas I know from experience that it does cake, but not so freely as the Grey. Possibly it was so much deteriorated before reaching Woolwich, that its caking qualities were destroyed.

"From all the trials, we have a right to conclude, that West Coast coal is 15 per cent. better than either average North of England, or New South Wales coal; and very much superior indeed, in the matter of clinker and ash.

"This is a matter of the utmost importance in the Panama service, particularly where the whole distance from Wellington to the Isthmus is to be performed by rather small steamers, without a coaling station.

"This is expected to occupy about twenty days, and as engines of five hundred horse power will probably consume about fifty tons a day, one thousand tons at least will be required for the run. Now, if West Coast coal was used, there would be a saving of one hundred and fifty tons on this, and, consequently, one hundred and fifty tons more space would be available for cargo and passengers. This of itself would be an important item in the balance-sheet of the Company.

Proceeding northwards from the Buller River this Anhydrous coal has been discovered in the Mokihinui, Heaphy, and most of the other streams that flow to the westward, and always apparently of the same useful description; – but the most important development of this formation which remains to be mentioned is that lying between West Wanganui harbour on the west side, and Pakawau on the east of the promontory that terminates in Cape Farewell. The coal formation is not however confined to the West Coast, as it has been found at the Batten and Wangapeka Rivers, which are at a distance of thirty miles from the coast and flow into Blind Bay. Mr. T. R. Hacket, Mining Engineer, informs me that, in West Wanganui, the coal seams occur at the sea level with a gentle southerly dip, and can be easily worked, – the total ascertained thickness of two contiguous seams being eight feet of available coal.

The quality is apparently inferior to that of the Buller and Grey coal, from the specimens analyzed (see Appendix): nevertheless it has been tested practically in steam vessels with satisfactory results, and systematic workings are about to be commenced, twenty cargoes having already been shipped from surface working between tide marks.

The harbour of West Wanganui is reported safe for vessels of ten

to twelve feet draught, and is considered superior to either the Buller or Grey harbours.

At Pakawau, which is on the East Coast, at a distance of seven miles from West Wanganui, the coal seams have been explored and worked to a considerable extent, but up to the present time without any satisfactory results, on account of the irregularity of the strata and the mixed nature of the coal.

At Aorere, which is seven miles south of Pakawau, and equi-distant from the outcrop at West Wanganui, coal has been long known to exist, and lately a valuable seam has been discovered under circumstances favourable for its development.

At the Batten and Wangapeka Rivers, although the existence of the coal is established, the value of the seams is not clearly ascertained. The disposition of the coal fields along the western slope of the South Island, and their association with other sources of mineral wealth and large areas of valuable land, render it almost certain that the route that will be first adopted for railway communication will be by the west side of the mountains, and thus pass through districts that will afford employment to a condensed population.

Already sufficient information has been collected to make it certain that no insuperable engineering difficulties would be encountered in carrying such a scheme into effect.

When this railway has been constructed, it will afford the means of transport by which the coal produced in the Western fields can be economically distributed over the country.

From various estimates which have been made by competent engineers, there appears however to be no doubt that, even with all the present disadvantages, the coal from the Buller and Grey fields could be delivered to steam vessels in Cook Strait at a cheaper rate than the present price of the coal imported from New South Wales.

In addition to the coal fields on the West Coast of the Middle Island, extensive tracts of the same formation occur on the east side of the mountains, that contain seams of Anhydrous coal, which are however of no great thickness, and of very uncertain quality.

The best of these is at Shag Point, in the Province of Otago, where the coal occurs with the same fossiliferous strata as at Pakawau and the Grey River, but has more the composition of a non-caking cannel coal.

This coal, the principal seam of which is five feet thick, is mined

and used to a small extent in the Province of Otago, but, so far as yet developed, has only local importance.

The coal mentioned in the Appendix as from the Kowai River, Malvern Hills, in Canterbury, is of excellent quality, but has not been discovered in workable seams.

The formation which has been reported on by Dr. Haast occupies a basin among the mountains, but in quite an accessible position. The strata dip at 60 deg. to 70 deg. and the breadth of their outcrop is described as 6000 ft.

This coal probably belongs to a lower series of coal measures than any of the above-mentioned Anhydrous coals, and to which the coal found at Waikawa, in the south-east of Otago, also belongs.

The extent of the coal formation in the last-mentioned district, consisting of indurated sandstones and conglomerates, is very great; and if good workable seams were discovered, this harbour would be a most favourable locality for shipment.

The only seams yet discovered, however, are less than twelve inches thick.

With reference to the occurrence of steam coal in the North Island, in the northern part of the Province of Auckland there is a large development of the same coal formation as that on the west coast of the South Island, containing seams of Anhydrous coal of considerable value, though their extent and persistence over large areas has not been established. This formation occupies the interior of the northern district, being separated from the sea on the east by ranges composed of slate rocks, – penetrated, however, by several excellent harbours – while on the west it is overlaid and cut off by recent tertiary and volcanic rocks.

The outcrop of this coal formation has been detected in a north and south line from fifty miles north of Auckland to Wangaroa Harbour, and there are also indications of its existence in the neighbourhood of Hokianga, on the west coast.

A large portion of the isolated mass of hills at the North Cape is also composed of this formation; and on the north side of the harbour of Parenga-renga, natural sections show these strata to be more than a thousand feet in thickness, although the coal is here only represented by very thin and worthless seams.

The only attempts to open mines in this section of the country have been made in the vicinity of the harbour of Wangarei, seventy

miles north of Auckland, and on the Kawa-kawa River, which enters the Bay of Islands.

At Wangarei the mine, which is a private enterprise, was opened about twelve months since, and in March last was nearly in full working order. It is situated about three and a quarter miles to the north-west of the point to which a tidal river may be navigated by barges drawing six feet, by which it is proposed to take the coal six miles down the stream to a part in the harbour where wharfage can be constructed, alongside which the largest vessels could lie in safety.

The tramway to the upper barge wharf is now complete, the rails being for the present of wood, but the sleepers being sufficiently heavy to bear iron rails and steam traction at a future time if desired. The mine is opened as a drive which enters the face of a hill from a narrow gully, up which the tramway winds in a heavy cutting for the last half mile of its length, the first part being through a level scoria plain, with only a very gentle gradient and constructed at comparatively little expense.

The coal dips into the face of the hill, resting almost immediately on slate rocks and overlaid by marine strata of a newer formation, which again are capped by extensive sheets of Doleritic lava that form flat-topped hills, and occasionally rise into Trachytic cones.

The altitude of the mouth of the mine is 424 feet above the sea, and that of the volcanic plateau 664 feet.

The seam has a very gentle dip, and though traversed by small faults, can be worked under very advantageous circumstances, as a large extent of the seam is "won" level free.

As the discovery of a coal outcrop occurring under such exceptional circumstances, must be merely accidental, it is probable that several other mines may yet be opened in the neighbourhood, though no indication of the existence of coal seams has yet been obtained nearer than at Hikurangi, which is sixteen miles north of Wangarei.

At the Kawa-kawa River the coal seam which has been discovered, though of more valuable quality and thicker than that at Wangarei, can only be worked under less advantageous circumstances, as the small altitude above the sea at which the coal is found will make it necessary to have recourse, from the commencement of the operations, to shafting and pumping, both of which are obviated in the case of the Wangarei mine.

The coal is, however, so much superior in its heating qualities, in

which respect it is second to none yet found in New Zealand, that before long it is certain to be extensively worked, and from the structure of the country there is reason to believe that it may yet be found in the same district under more favourable conditions for opening a mine, in which case the coal from this locality might be able to compete with that from the West Coast of the Middle Island.

The only work which has been executed is an experimental shaft, sixty feet in depth, and twenty yards from the out-crop, which is seventy-two feet above the bed of the Kawa-kawa River. In this shaft the thickness of the coal was 13.6 feet, only part of which was compact enough to bear working, but it might reasonably be expected to improve in this respect as the overlying strata increased in thickness with the dip.

About twenty-eight holes were also bored in the neighbourhood to a depth in some cases, of 130 feet, but in only one of them was the coal cut at such a distance from the outcrop as to afford any indication of the lay of the coal seam.

From the only locality where the coal has yet been discovered in this district a tramway of three miles is necessary to reach a point on the Kawa-kawa River, where there is sufficient draught of water for barges by which the coal might be conveyed down to where vessels can be loaded, but on account of the extremely friable nature of the coal it would be preferable to continue the tramway to this point in order to avoid transhipment. The distance would be nine miles, and on account of the heavy works requisite in some places it would be a very expensive undertaking. Notwithstanding these drawbacks, which may certainly affect the immediate development of this coal field in the present state of the Colony, there is every reason to expect that it will ultimately occupy a prominent position among the coal producing districts of New Zealand.

A summary of the most important features of the various localities where it has been proposed to work the Anhydrous coals in New Zealand is given in the following tabular form.

Sufficient information as to the extent of the various coal seams in these localities has not yet been obtained to enable an estimate being shown in this table of the amount of coal existing in any of them; but by the most moderate computations founded on the extent of the coal formations, it would not be presuming too much on analogy to expect that there is not less than four thousand millions of tons of coal available in New Zealand.

The quantity of coal imported into New Zealand annually since 1853, as compared with the population, is shown in the following extract from the Statistics of the Colony, from which it will be seen that the consumption is steadily increasing, and that in the last year there has been a very marked fall in the price.

QUANTITY and VALUE of COAL IMPORTED into New Zealand; also the Yearly REVENUE and POPULATION from 1853 to 1865.

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1 Memoirs of Geological Survey of Great Britain, vol. II., page 558.

2 Nelson Provincial Government Gazette, 6th July, 1866.

3 All the samples examined in the Geological Surrey Laboratory caked.

APPENDIX

APPENDIX.

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APPENDIX.

Enclosure A.

Extracted from Supplementary Report on Class I., New Zealand Exhibition, 1865, pages 373 to 387, and 439 to 443 – "Anhydrous Coals of New Zealand."

AUCKLAND.

I. – BITUMINOUS COAL, KAWA-KAWA, BAY OF ISLANDS.

This coal, the geological formation of which is unknown, appeared of superior quality to any other of the Auckland coals. 4 Its color was black, but in part it was covered with brown films. Its lustre is resinous; fracture and cleavage very irregular and granular; moderately hard. It burns freely; powder and streak, dark brown and glistening; coke cakes, but does not puff up as do the Nelson and Canterbury bituminous coals. This is a great advantage where a high heat is necessary, as the draught is not likely to be impaired. It is also very porous and coherent; the ash is light red and easily blown away.

NELSON.

II. – BITUMINOUS COAL, PAKAWAU. 5

[Specimen I.]

This is of upper secondary age, and is a harder coal than that from the Grey River, but of less brilliant lustre. It burns freely, with a smoky flame; fracture slaty along its cleavage, but across it conchoidal; powder and streak, black brown; coke, semi-metallic, caking to a very coherent mass; ash, light buff; percentage of coke, 58.36, and of sulphur, 1.04.

An examination of this coal proved it to be similar in composition to a sample from the same locality previously analyzed in the laboratory of the Otago Geological Survey.

III. – BITUMINOUS COAL, PAKAWAU.

[Specimen II.]

This coal, taken from a seam 1 foot thick, varied greatly in its composition, part of it having a black resinous lustre, and conchoidal fracture, and containing only 5.8 per cent. of ash. But the greater part, and that sample which was analyzed, is a very hard dull earthy coal; fracture, slaty; powder, dark brown; coke dull, coherent, hard; ash, light grey; percentage of coke, 63.2.

IV. – BITUMINOUS COAL, BULLER RIVER.

[Sample I.]

This specimen represented a single seam 9 or 10 feet in thickness. It is a pitch black lustrous coal, compact, but easily pulverized; burns freely, with a smoky flame; fracture splintery; powder and streak, dark dull brown; coke dull, coherent, puffs up slightly; ash dark buff, easily blown away. The percentage of coke is 65.85; that of sulphur, 1.20.

V. – BITUMINOUS COAL, BULLER RIVER.

[Sample II.]

This coal is singularly free from impurities, and from its external appearance and composition evidently bearing a close relation to the column of coal from the same locality. This sample was not quite so lustrous as some of the Grey River coal, but it had a glistening appearance on certain cleavages. Its fracture is rhombohedral. It easily pulverizes to a brown powder, and yields 58.0 per cent. of a very porous semi-metallic coke. The ash is light buff.

VI. – COAL, BULLER RIVER.

[Sample III.]

A dull black looking coal; the powder, however, presenting a glistening appearance. It is tolerably hard and compact.

The coke is semi-metallic in lustre, very porous and hollow, possessing little coherence. The ash is white. The yield of coke is 67.40 per cent., and its specific gravity from 1.160 to 1.250.

VII. – BITUMINOUS COAL, BULLER RIVER.

[Sample IV.]

This is rather a friable coal, easily pulverizing. Its lustre is brilliant, and its powder has a slight shade of brown, though the coal in bulk is black.

The fracture is conchoidal. Color of ash white. When heated in a closed crucible it puffs up to a hollow ball, and leaves, on a continuation of the process, 67.84 per cent of semi-metallic coke.

VIII. – BITUMINOUS COAL, GREY RIVER.

[Specimen I.]

The beautiful iridescence exhibited by this coal when broken in the direction of its cleavage recommended it for analysis. It appears to be due to the presence of thin films of a white opaque salt.

The cross fracture is black; lustre, resinous; powder and streak, dark brown; coke dull, puffs up a little, coherent; ash, gray. The percentage of coke is 64.22.

IX. – BITUMINOUS COAL, GREY RIVER.

[Sample II.]

This is a beautifully bright clear homogeneous coal. The fracture is generally uneven; in parts, however, plain surfaces are displayed. Its powder is brown, the ash white, and does not appear to have the least tendency to clinker. Ignited it burns freely, evolving a good flame, and coked in the usual manner it swells up considerably to a porous coherent mass, leaving about 61.20 per cent. of semi-metallic coke.

X. – BITUMINOUS COAL, GREY RIVER.

[Sample III.]

A coal similar in appearance to No. XI., but having a greater quantity of ash present. Powder and streak, brown; ash, white. It gives a dull looking coke, which puffs up to a very great extent.

CANTERBURY.

XI. – BITUMINOUS COAL, GREY RIVER, CANTERBURY.

A very compact coal of secondary age, difficult to pulverize. Its color is black; lustre dull. The fresh fracture, however, has a glistening appearance. It possesses a slaty cleavage. Powder of coal, black; ash, light brown. The coal puffs up slightly when heated, and gives 68.37 per cent. of metallic coke.

XII. – BITUMINOUS COAL, MALVERN HILLS.

A hard black glistening coal, and burns freely with a smoky flame. Fracture, uneven; powder, dark brown; streak, brown; ash, white, and easily blown away; coke, dull, and puffs up greatly.

OTAGO.

XIII. – PITCH COAL, SHAG POINT, THIRTY MILES FROM DUNEDIN.

This, which is the freest burning coal in Otago, is probably of upper Mesozoic age. It corresponds exactly with Dr. Percy's definition of pitch coal, and may be considered to hold the same relative position among the Brown Coal series that cannel does to the true or older coals.

It is very compact; does not absorb water or soil the fingers. Its color is a brownish black; fracture, conchoidal and splintery; lustre, fatty, resinous; streak, lustrous, and gives a dull brownish black powder. It burns freely, with a rich oily flame, giving off only a slight odour, and leaving a bulky, but light argillaceous ash.

Upon distillation it gives off a rich gas at high temperature, and a large yield of gas oils, if a low heat be carefully applied. The coke is light, and semi-metallic, and its percentage 50.68, and that of the sulphur, 4.78.

This large percentage was arrived at by repeated determinations. Part of it seems to be combined with the gaseous matter, in the manner referred to already in the introductory remarks. 6

XIV. – SEMI-BITUMINOUS COAL, FROM WAIKAWA.

This is of upper secondary age, and occurs in seams less than twelve inches in thickness, imbedded in sandstone grits. It is very similar in appearance and composition to that from Preservation Inlet – color, jet black; powder and streak, brownish. It is laminated, somewhat fragile, but does not crack on exposure. Many of its cleavage planes show a dull brown color. Its coke does not cake. Ash, white; and as is frequently the case in these thin seams, its quantity is very large.

XV. – SEMI-BITUMINOUS COAL, PRESERVATION INLET.

This is of upper secondary age; the samples were procured from very thin and impure seams, and present great irregularities in their composition and external appearance. It is hard, compact and black, with a splintery cubical fracture rarely conchoidal; powder, black, with a faint brownish tinge in some samples; streak black and shining; ash, light buff; coke unchanged, and does not cake.

Owing to the varieties of character which the samples present, three distinct analyses are given.

Enclosure B.

Further information respecting the chemical qualities of various New Zealand Coals: being the results of investigations made in continuation of those given in Enclosure A.

COAL FROM WALTON'S MINE, WANGAREI, PROVINCE OF AUCKLAND.

This coal is obtained from a seam about five feet in thickness, and, as it presents a considerable diversity of physical appearance in different parts of the seam, four samples were analyzed.

Sample I. was taken from the heap at the pit mouth in December, 1865, and was the average quality of coal obtained in the mine at that date. It is a black laminated coal with a conchoidal or uneven fracture, easily pulverized to a dark brown powder, burns freely, with a smoky flame, gives 48.70 per cent of non-coherent semi-metallic coke, and leaves a large quantity of grey silicious ash that is nearly free from iron.

Sample II. was taken from a stone band or impure layer that traversed the middle of the seam. This band near the outcrop was four to six inches in thickness, and the great difficulty in separating it from the coal – which could only be done by hand dressing – at first added largely to the expense of working the mine. As the seam was followed back from the outcrop this band has gradually thinned out, and in March last it had quite disappeared, while the pure coal had increased to a six foot seam. This band proved to consist of a mechanical mixture of sulphurous clay iron-stone with coal of the same composition as sample No. 1, the incombustible matter being as much as 44.80 per cent.

Samples III. and IV. were taken from the working face of the mine in March, 1866, where the seam presented two distinct varieties of coal.

III. formed the greater part of the seam, and is a hard compact coal capable of resisting pressure, and therefore fitted to bear transport without falling to dross. It is of a lustrous black color and traversed by alternating layers of jet and dull coal in the same manner as most of the varieties of coal from New South Wales. It contains bright films of iron pyrites and small pebbles of quartz. In other respects it is similar to sample No. I. to which its greater compactness renders it on the whole superior, notwithstanding, as will be seen from the analysis, that it contains more both of water and ash.

Sample 4 is from a stratum in the middle of the main seam about one foot in thickness, and is characterized by extreme friability.

Being very bright and lustrous, and having a small proportion of ash and large quantity of water in its composition, it resembles jet.

It is singularly fragile, breaking in small fragments under the slightest pressure.

When on board the small steamer that plies between Wangarei and Auckland, I had an opportunity of observing this coal used for raising steam, and comparing the results obtained with those from Newcastle coal.

I had one of the three fires fed with the Wangarei coal only, another with the Newcastle coal, and a third with a mixture of the two.

The Wangarei coal was far from being a fair sample, as it contained a large proportion of the "band" intermixed with it. In consequence of this it formed a very bad clinker, which being very fusible set to a hard slag, which was difficult to disengage from the furnace bars.

The Wangarei coal gave out a most intense heat, burning with a clear white flame; the flame of the New South Wales coal being red and smoky.

About one-third more of the Wangarei coal than of the Newcastle coal was required to keep the fire in good order, but the furnace fed with mixed coal appeared not only to burn more freely but to require no larger quantity than of the Newcastle coal when used alone.

The only defect when the mixed coal was used was the formation of clinker, but this will, I believe, be much reduced in quantity in the coal now obtained from the mine.

The results I subsequently saw on board the same steamer, in March last, quite confirms me in this opinion, and I have no doubt that for coasting steamers this coal will prove a most valuable fuel.

Wangarei – Walton's Mine.

COAL FROM KAWA-KAWA RIVER, BAY OF ISLANDS.

This coal was analyzed and previously reported on in the Exhibition Jurors' Report page 384, (vide Enclosure A.,) samples of it having been sent to Dunedin in 1865; but since then the locality has been visited and examined geologically, and further analyses have been made.

The main seam is only visible at an outcrop in the bed of a small creek, and in immediate contact with Diorite slate; but a shaft was sunk through the seam about sixty feet from this outcrop, by which there was found to be a total thickness of thirteen feet six inches of pure coal, but broken into two or more subordinate seams by "partings" of shale and chert. The seam was also pierced by a bore at 200 yards distant from the shaft in the line of strike, and the result proved it to have varied very considerably in the order and thickness of these clay partings.

Many other borings were made in the neighbourhood, but none were continued to sufficient depth to reach the coal, so that we have no information regarding the persistence of the character of the coal over a large area.

The geological age of this coal is identical with that in Walton's mine at Wangarei, and also with coal which I examined at Hikurangi, a locality midway between Wangarei and Kawa-kawa, and there is every reason to believe that the coal field is more or less continuous throughout a large district.

The coal from these several localities appears to be of very different qualities, however, and in the case of the seam at Kawa-kawa is exceptionally good.

From its possessing chemical and physical characters that distinguish it from all other New Zealand coals, we may expect that these peculiarities are in some manner connected with its valuable qualities, and that both are perhaps due to local causes which may have operated over only a limited area.

The mineral characters of all the specimens of the coal from the main seem are identical. It is of a brownish black color, with a marked resinous lustre, and shortness of grain, that at once distinguishes it. Its cleavage in large masses is cuboidal, but can hardly be detected in small fragments, as its structure is almost granular.

It burns very freely with a rich flame, and most intense heat. It cakes slightly, but when coked does not swell or puff up. The quantity of ash is very small, but that of sulphur large, a portion of it existing in an oxidized form.

This is a very marked peculiarity of this coal, considering that it is remarkably free from iron pyrites and the clay matter that might cause the formation of aluminous minerals on exposure to the air. As a steam and forge coal, it appears from the reports of experiments that have been performed to have a very high value, and the only objection to its use for the former purpose will be its extreme friability, as very little handling will convert it into dross.

What appears to be a second seam was discovered by Mr. Moodie in the bed of a small stream about half a mile distant from the first discovered outcrop.

The coal from this seam has the external appearance of being very inferior, and approaching more to an ordinary earthy brown coal, but on being analyzed it was found that its greatest point of

difference was in the large quantity of ash that it contained, the percentage of water being even rather less than in the coal from the main seam.

Both the seams of the Kawa-kawa coal, and also the coal from Wangarei and Hikurangi, contain masses of retinite or fossil resin, and also quartz pebbles embedded in them, which, along with the peculiarity in the first mentioned coal, of having a large quantity of sulphur in its composition, uncombined with iron, connects the coal of this northern district closely with the common brown coals, their redeeming feature being the low percentage of water which they contain. Considered from this point of view, however, there exists quite as wide a distinction between the Wangarei coal and that from Kawa-kawa as between the Wangarei coal and the Hydrous Brown Coal from the Drury mines.

The value of the Kawa-kawa and Wangarei coal for the purpose of manufacturing gas was tested practically by Mr. J. N. Wark, the manager of the Auckland Gas Works, and the results given in his reports, which are appended hereto, show that while the Kawa-kawa coal yields the largest quantity of gas, viz., 11,660 cubic feet per ton, the yield of the Wangarei coal being only 8,500 cubic feet per ton, the quality of the gas is better in the latter case.

It will be observed, however, that the Kawa-kawa coal produces a large percentage of marketable coke, while the coke of the Wangarei coal is very inferior.

Kawa-kawa Coal – Main Seam.

2. Kawa-kawa – Moodie's Outcrop.

REPORTS OF EXPERIMENTS AT AUCKLAND GAS WORKS.

Gas Works, Auckland,

1st December, 1865.

SIR, –

I beg to submit to your Honor the following experiments on Bay of Islands or Kawa-kawa coal: –

This is a coal which I think would be called a "cherry coal," – it does not melt or cake but to a very limited extent, consequently the coke is not large but of excellent quality. It gives off the gas freely,

and the illuminating power is about equal to that of the coal I have usually had from Newcastle. Evidently it contains more sulphur, but there is no difficulty in separating this ingredient from the gas. Therefore by comparison, although the cost of purification may be increased in respect of the Kawa-kawa coal, a larger quantity is taken off in shorter time. The residue in coke is at least 10 per cent. greater, and the quantity 20 per cent. superior.

In testing the value of any coal commercially, it is not easy to give a satisfactory approximation to the proportions of volatile matter coke and ash produced; obviously the exact quantities of tar, water, ammonia, sulphur, &c., belong to those nice arrangements of the laboratory of the chemist.

Therefore your Honor will pardon me if I have not attempted what seemed beyond my sphere. It may be observed that none of the experiments give exactly the same results. This is common: One part of a seam of coal might be superior to another, which would tell on the quantity or quality of gas or coke; or in quenching the coke a larger amount of water might be used at one than another time. This latter I think was the case in regard to at least the first experiment. The heat of the retort used was pretty equal during all the experiments, not less than what I understand to be about 1500 Fah. so to secure a good and uniform result.

I may further remark that I have tried the coal with the usual mixture of Lesmuhago, and the illuminating power seemed about the same as is usually supplied. I also tried it with about 1 in. 15 of kauri gum scrapings which I had at hand, and the result was similar.

I am, &c.,

J. N. WARK.

To His Honor the Superintendent of the Province of Auckland.

Gas Works, Auckland,

12th December, 1865.

SIR, –

As you have entrusted me with a quantity of coal from Wangarei, for the purpose of testing its value as a gas producing coal, I have the pleasure to report to you as follows: –

The result of the under-noted experiments shows that the coal yields about eight thousand five hundred cubic feet of gas to the ton.

The first experiment was protracted an hour longer than the other two, because I thought the heat not up to the mark, consequently a larger quantity of gas was obtained, but the quality would naturally be depreciated. The quality of the gas, however, is superior to that of any coal that has yet come under my notice in the Colony. The quantity of sulphuretted hydrogen is, I fear, above the average. It is not a fusible coal, and the coke produced is small and friable, while the quantity is not great.

Altogether it is encouraging that a coal of so good a quality is at hand.

I am, &c.,

J. N. WARK, Manager.

To Mr. Walton.

Wangarei Coal (Mr. Walton's) 11th December, 1865.

PAKAWAU COAL, NELSON.

Several samples of coal from fresh localities in the Pakawau and West Wanganui District have been sent to the Museum, which, on the

whole, prove to be rather superior to any that have been previously analyzed. (Vide Enclosure A.)

The first sample examined was obtained by a shaft that was sunk 46 feet below the surface, in October last, from a seam 3 to 4 feet thick.

It is hard, compact, and lustrous, and indistinctly laminated. At first it burns freely, with a smoky flame, but, after the gaseous matters are consumed, the remainder, or more than half the bulk of the coal, can only be consumed with the aid of a powerful draught. It cakes slightly in burning but does not swell or puff up. Seams of coal have now been discovered in many parts of the Massacre Bay District, and there is every reason to believe that the coal-bearing deposits are very extensively developed in that part of the Province of Nelson as well as towards its southern border, where the commercial value of the coal is now thoroughly established.

The most recent discovery in the Northern District is on the Aroere River, where a seam, at least 4 feet in thickness, has been discovered, apparently of a very superior quality of coal.

Two samples of this coal have been examined, both furnished by Mr. Wells. They are of a glossy jet black and laminated structure. Their powder and streak is dark brown.

Sample I. which is from the lower part of the seam leaves a buff colored ash, and though it cakes it does not puff up.

Sample II. is from above a "clay parting" in the seam, has a gray colored ash, and swells in coking to several times its bulk when in powder.

In both cases, as in the first mentioned coal from Pakawau, the coke burns only with a strong draught.

Details of Analysis – Pakawau Coal.

An average sample of the coal found at West Wanganui, selected from a small quantity sold in Nelson, was also furnished for analysis by Mr. Wells. It proved to contain a larger quantity of earthy matter than is usual, and as it has only a small percentage of fixed carbon, and does not cake or form a coke, it appears to have more the character of a bituminous shale than a steam coal.

Its cleaveage and texture is, however, good, and it exhibits alternations of dull earthy coal, with flakes of pitchy lustre as in New South Wales coal. Its powder is dull brown, and its ash of a pale brown colour.

Analysis.

A further sample of West Wanganui coal was received from Mr. Otto Wiesenhavern, and on being analyzed gave the following results: Character – Massive, compact, hard, possessing plain cleavage in all directions; appearance generally dull, but in parts having a jet-like lustre; surface dulls on exposure, but does not break up It has thin veins of iron pyrites traversing it. The coke, which is only slightly coherent and lustrous, amounts to 54.30 per cent.; color of ash, red.

Fixed carbon ............ 50.10

Hydro carbon ..... 37.10

HYDROUS PITCH COAL FROM KAIOU RIVER, WANGAROA HARBOUR.

This specimen, which is said to be from a very thick seam in the upper part of the Kaiou River, which flows into Wangaroa Harbour, was given to me by Henry Williams, Esq.

Although its composition places it among the Hydrous Brown Coals, from the section of the strata with which it is associated and from some of its characters, I am inclined to think it belongs to the same group as the Kawa-kawa and Wangarei seams.

In physical appearance it might be mistaken for some of the samples from the Grey River on the West Coast of the Middle Island, especially in its lustre, which is singularly bright and glistening. It burns with ease, and yields a non-coherent metallic coke. The ash is of a bright buff color. Composition: –

BITUMINOUS SHALE, AWATERE, NEAR MONGONUI.

The locality given for this mineral, of which only a small sample has yet been obtained, is on the authority of the Rev. R. Taylor, who discovered it many years ago.

Grey micaceous sandstones of upper secondary age occur at the locality indicated, and contain carbonaceous layers with plant impressions, but no seam of this substance can now be detected; however, as the cliff is being constantly worn away by the action of the sea, the original site may have long since disappeared, but, as the same mineral

may occur in other parts of New Zealand, its properties were carefully examined.

From the composition of this mineral it will be seen that it approaches closely to the famous Torbane Hill oil shale in character, to which it also bears a considerable external resemblance, with the exception of being rather darker and more resinous in lustre. Its properties are as follows: – very coherent, close grained, hard and tough, almost elastic, does not show the slightest indication of lamina or cleavage planes, having a smooth semi-conchoidal fracture in every direction.

What appears to be the exterior portion of the stratum is of a yellow color, while the rest is of a dull black color, and perfectly homogeneous in every part.

It is exceedingly difficult to pulverize this mineral, but when a moderately fine powder is obtained it has a very decided brown or chocolate color. Its specific gravity is 1.112.

It ignites with ease and bursts into a flame which is sustained for a long time with great vigor.

The flame is at first very luminous and bright, but soon becomes long and smoky, and during combustion small oil bubbles may be seen escaping.

The presence of oil to a large extent among the volatile matters escaping at comparatively low temperatures, is best observed by heating the substance in a partially closed test tube to a temperature of 400 deg. Fah., after previously drying it at 212 deg.

The oil is then seen to condense upon the cooler portion of the tube in considerable quantity, and when finally removed to a cold place a large portion of the oily matters solidify to a white substance, probably paraffine.

When heated to a dull red heat, in a closed crucible, till no more gaseous matters are evolved, there remains about 23.00 per cent. of light non-coherent cellular and slightly lustrous coke, and this in the open fire was found to burn readily to a perfectly white ash.

In order to compare this bituminous shale with others of known value, samples of the oil shale from New South Wales, and of the Torbane Hill mineral, were analyzed at the same time, and the following table gives the results obtained, together with the composition of the several other shales from which oil is distilled, as given in Gesner's work on "Distilled Mineral Oils."

* Those marked with asterisks have been examined in this Laboratory.

From an inspection of the above columns it will be observed that while the New South Wales and the Mongonui samples are for all practical purposes alike, and indeed might well have been taken from the same seam, they are both superior, as far as can be judged, to any of the rest, which, it may be remarked, were purposely selected for comparison, on account of their excellent quality.

It should be stated, in order that the value of these oils may be properly appreciated, that the yield of gas from the Torbane mineral is 13.000 cubic feet per ton, of a specific gravity of 0.775, the quantity of crude oil is 120 gallons, of which 65 gallons may be made into lamp oil, 7 gallons of paraffine oil, and 12 lbs. of pure paraffine.

The Breckenridge coal yields 130 gallons, 58 per cent. of which can be manufactured into lamp oil, and 12 gallons into paraffine and paraffine oil.

The Albert coal yields 110 gallons of oil per ton, 70 per cent. of which can be made into lamp oil, and 10 per cent. is heavy oil and paraffine.

These particulars are extracted from the same work on Coal Oil and Petroleum, previously quoted.

It may be noted that the coke from these bituminous shales is used as a disinfectant, being admirably adapted for this purpose from its incoherence and pulverelent structure, by which it affords a large surface. The coke from this particular sample was found to exhibit very decided properties of this kind.

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4 For further information see Enclosure B.

5 See also Enclosure B.

6 P. 379, Jurors' Reports.

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