2. General Notes on the Coal-Fields. North Island.

(1) Auckland Coal-fields.

The province of Auckland, which exhibits such a profusion of metalliferous ores, is but poorly provided with coal, for while the deposits are fairly numerous, the quality, except in the cases of Kawakawa and Hikurangi is inferior, and even in these two instances, it cannot be described as actually first-class. There are five districts; in the extreme north Wangaroa and Mongonui, next Kawakawa at the Bay of Islands, with Hikurangi between that area and the Whangarei field. Lastly Drury and Waikato, including Miranda.

The Wangaroa and Mongonui fields do not at present require notice, for although the coal at the former place is of fair quality, it has not been worked.

The Kawakawa coal-field is on a different footing, as the output has been largely used by ocean-going steamers. The pit is now on the eve of exhaustion. Plucky efforts have been made to discover either an extension of the seam, or fresh deposits, by the aid of the diamond drill, but to no effect, and the output has declined to 28,254 tons in 1891, raised by 70 men. The total since the commencement is 737,249 tons, in twenty-six years, during which time the concern can hardly be said to have been a commercial success.

The coal is brought to bank by an engine-plane, and the pumping is (or was, for the writer fancies it is now stopped) carried on by means of heavy pumptng-gear in a shaft to the dip. The seam was originally 13 feet thick, but varies much, and the workings were pillar-and-stall. The roof is bad, and the slack very prone to spontaneous combustion. The port of shipment is 8 miles from the mine, and the produce is con- page 68 veyed on a Government railway, which cost £86,283, The seam was originally found in 1868 by a person in search of Kauri gum, and it is a matter of deep regret that a good coal, worked by an enterprising company, under capable management, should not have brought a better reward. Two samples of the coal gave on analysis:—

	Per Cent.	Per Cent.
Fixed carbon	57.20	55.59
Hydrocarbons	36.00	38.10
Water	4.60	4.19
Ash	2.20	2.12
	100.00	100.00

The area of the field is stated to be 10 square miles, and no doubt when railway communication is established, the output will be considerable.

The Whangarei district has the advantage of a railway leading to a port from which the coal can be shipped, and has been worked for about twenty-eight years.

The Cretaceo-Tertiary rocks which lie unconformably on the slates, are much obscured by newer volcanic formations, Formerly two mines were at work, but one of these is now closed, and the Kamo mine has the whole trade. This concern put out in 1891, 15,652 tons, which was a decrease from the amount raised in former years: the reason appears to have been that during that year a creep extended over the workings, and caused a cessation of work.

The seam consists of a lustrous black coal, and is found to range up to 14 feet in thickness: a little explosive gas is found, and the slack takes fire spontaneously. The shaft is 240 feet deep, and the cage is fitted with safety-catches and detaching-hooks. The system employed in working is bord-and-pillar. The analyses of a few samples are:— page 69

	Per Cent.	Per Cent.	Per Cent.
Fixed carbon	52.63	49.08	50.01
Hydrocarbons	34.30	37.57	37.67
Water	8.91	9.24	9.01
Ash	4.16	4.11	2.69
	100.00	100.00	100.00

To the south of Auckland city, and situated both on the large river Waikato and on the railway which skirts it for so many miles, is the Waikato coal-field, which is likely in the future to play an important part in the commercial history of the colony.

The coal produced is clean-looking, black and lustrous, suitable either for household use or steam purposes. It is, however, of low specific gravity, and desiccates so rapidly on exposure to the air that it is useless for storage. In the mines it is subject to spontaneous combustion.

The seams were originally worked where they crop out on the banks of the Waikato river, and are found from 6 to 65 feet in thickness. In 1891, five mines were in operation, which yielded a total of 55,859 tons, and employed 164 men. This number includes the Miranda mine. Two are worked by shafts, the othera by adit level. At the Taupiri Extended mine the shafts, recently sunk was put down with considerable difficulty, as it was necessary to force down iron cylinders, which met with obstacles in the form of driftwood. Before the second shaft was sunk a circle of boreholes was made, to see if any similar obstruction existed. The cast-iron segments were then lowered, and the sand and drift removed by a dredge, without any water being pumped. The Taupiri Reserve mine, which turned out in 1891, 17,221 tons, worked under Luke Kimihia. By boring, the cover over the seam was found to be from 48 to 77 feet thick, mostly strong fireclay. The bonds am 14 feet wide, and the pillars 21 feet, and of the 18 feet total thickness of the seam 5 feet is left for a roof. It thus appears that laterally 40 per cent, of the support is removed, and it is reasonable to suppose that by flaking of sides and driving of cross-cuts another 10 per cent, will be lost. This makes the spaces and pillars equal, which seems rather risky.

At Maramarua creek, near the Miranda Kodoubt, a mine was for some time worked on a seam 54 feet in thickness, or even more, but it was closed in 1890, after a somewhat disastrous career. The output for that year was 228 tons and the total 20,668 tons. The pit was sunk on the edge of the Maramarua creek, a tributary of the Waikato river, and a canal costing £1,800 was cut to bring the coal to the main stream, by which it was brought down in punts to the railway siding at Mercer, where steam page 70 cranes raised the boxes from the punts and emptied them into the railway trucks. The lease consists of about 1,000 acres, and the coal is of good quality; but the mine appears to have been injudiciously worked, or else it should have done better. Water, too, constituted a considerable drawback, and In 1837 it was necessary to draw water for 16 houra out of the 24. This work and the small sheaves which were used wore the winding rope out in two months. The following is an analysis of Waikato coal:—

	Per Cent
Fixed carbon	47.08
Hydrocarbons	33.24
Water	17.60
Ash	2.08
	100.00