General Description.

Class I.—The Hydrous Coals of the South Island occur on the eastern coast chiefly.

Pitch Coal has been worked since 1867 at West Wanganui, in Nelson; and in Otago at Shag Point, forty miles north of Dunedin, it page 37 has been worked since 1862, together with brown coal. It is also found at Reefton, Nelson, where it contains resin disseminated throughout its mass; Waikato and Whangaroa, Auckland; Morley Creek, Southland. It belongs to the Upper Cretaceous period, and has an evaporative power of 5.21b.

Brown Coal is extensively worked in Auckland, on the Waikato River, and in the Kaitangata Mine, Clutha district of Otago, where the seams are from 5 to 20 feet thick. The area of this latter coalfield is about 6,000 acres, and the quantity of coal has been estimated from surveys to be 140,000,000 tons, nearly the whole of which would be available without sinking. In the same provincial district thick seams of brown coal in grits and clay-shale have been worked since 1861 at Green Island and Saddle Hill, and extensive seams exist in Southland, and to the west of Riverton, which have not yet been regularly mined. It belongs to the age of the Upper Greensand, and has an average evaporative power of 4.21b. to 5.61b.

The Lignites of Lower Miocene age occur in the interior of Otago and at other places in superficial deposits of limited extent, and have been used chiefly by gold-miners.

Class II.—The Anhydrous kinds of coal prove to be quite equal to any imported, experiments having been undertaken in 1865 for ascertaining their value as steam coals. Both these and the hydrous coals occur at the base of a great marine formation, underlying limestone, clays, and sandstone of Cretaceous and Tertiary age, which have a thickness of several thousand feet, the coal-seams occurring whenever the above formation is in contact with the basement rock. The anhydrous kinds are more limited in distribution, and appear to have been produced by local disturbance of the strata, and in some cases are evidently due to the intrusion of volcanic rocks.

Bituminous Coal is worked chiefly in the Nelson District. At Mount Rochfort or Buller mines the scams are on a high plateau, and are 10ft. to 40ft. thick, and from 900ft. to 3,000ft. above sea level. Accurate surveys of this coalfield show it to contain 140,000,000 tons of bituminous coal of the best quality and easily accessible. A Government railway seventeen miles in length is now completed along the level country at the base of the ranges in which the coal occurs, and from which it is lowered by incline planes constructed by the coal-mining companies. The principal mine is the Banbury, which has a magnificent seam of hard bituminous coal at an altitude of 1,800ft. above the sea-level. At the Brunner coal mine, on the Grey River, Nelson, the working face of the seam is 18ft., and it has been proved to extend one-third of a mile on the strike page 38 without disturbance, and to be available for working in an area of thirty acres, the estimated amount of coal being 4,000,000 tons in this mine alone, most of which can be worked above the water-level. Coal-Pit Heath is a second mine lying more to the dip of the same seam. A third mine was for a time opened on the south side of the river, which, with a 370-ft. shaft, will command 300,000 tons. The coal from the Brunner Mine, Nelson, which has now been worked for fifteen years, yields vitreous coke, with brilliant metallic lustre. Average evaporative power of several samples, 7½lb. of boiling water converted into steam for each pound of coal. It occurs with grits and conglomerates of Upper Mesozoic age, corresponding to the horizon of the Gault or Lower Greensand. A railway has been constructed by Government to connect the mine with the port, and harbour improvements are in progress, whereby a larger class of vessels than at present will be enabled to enter the river. The small quantity of this coal hitherto obtainable in New Zealand and Australian markets has been eagerly bought up for gasworks and iron foundries, which generally pay for it from 10 to 20 per cent, more than for any other coal. Engineers of local steamers esteem it 20 per cent. better than the best New South Wales coal for steam purposes. Coke made from it is valued at £3 per ton.

Coalfields in other parts of the Nelson District have also yielded excellent coal. At Murray Creek, Inangahua, an 18-ft. seam of semi-bituminous coal is worked, associated with quartz grits. At Pakawau, and in the same formation at Collingwood, thin seams of hard bright bituminous coal have been worked from the sandstones of the Cretaceous period. The area of the coalfield is about thirty square miles, and the facilities of access and shipping and the abundance of iron ore and limestone will probably make this an important mining district. The chief coal mine has been opened by a tunnel 700ft. in length, piercing the mountain at 600ft. above the flats along the Aorere River, the coal being brought down by a self-acting incline. This description of coal also occurs in the irregular scams in sandstone of Upper Mesozoic age (Jurassic and Lower Cretaceous), at Kawakawa and Whangarei, Auckland; Mount Hamilton and Waikawa, Otago. It rarely cakes strongly, and has commonly an evaporative power of 6½lb.

Coal has been worked since 1865 in Auckland at the Kawakawa mine, Bay of Islands, from a seam 13ft. thick, under a roof of greensand; it contains much sulphur. A similar quality of coal is also worked at Walton's mine, and at the Kamo mine, Whangarei Harbour; and several important mines are opened in the coal-seams at the Malvern Hills, Canterbury.

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Glance Coal.—This description of coal does not form a caking coke, but slightly adheres, and is a variety of brown coal, altered by faulting or by igneous rocks, and presenting every intermediate stage from brown coal to an anthracite. Occurs at Preservation Inlet and Malvern Hills, of Lower Cretaceous age, in extensive but detached seams from 2ft. to 6ft. thick in micaceous and argillaceous shales.