The Pamphlet Collection of Sir Robert Stout: Volume 66
Mining and Geology : Economic Minerals. — Coal
Mining and Geology : Economic Minerals.
Coal.
Coal mines are being worked in the Provincial Districts of Auckland, Nelson, Canterbury, and Otago (including Southland).
Class I. | —Hydrous, containing an excess of combined water.
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Class II. | —Anhydrous, containing very little combined water.
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I. Hydrous Coal, containing 10 to 20 per cent, of permanent Water.
Lignite shows distinctly woody structure; laminated; very absorbent of water.
Brown Coal rarely shows vegetable structure; fracture irregular, conchoidal; colour dark-brown lustre feeble; cracks readily on exposure to the atmosphere, losing 5 to 10 per cent, of water, which is not reabsorbed; burns slowly; contains resin in large masses.
Pitch Coal.—Structure compact; fracture smooth, conchoidal; jointed in large angular pieces; colour brown or black, lustre waxy; does not desiccate on exposure, nor is it absorbent of water; burns freely; and contains resin disseminated throughout its mass.
II. Anhydrous Coal, containing less than 6 per cent, of Water.
Glance Coal.—Non-caking, massive, compact or friable; fracture cuboidal, splintery; lustre metallic; structure laminated; colour black; does not form a caking coal, but slightly adheres. This variety is brown coal altered by igneous rocks, and presents every intermediate stage from brown coal to anthracite.
Semi-bituminous Coal.—Compact, with laminae of bright and dull coal alternately; fracture irregular; lustre moderate; cakes moderately, or is non-caking.
Bituminous Coal.—Much-jointed, homogeneous, tender and friable; lustre pitch-like, glistening, often iridescent; colour black with a purple hue, powder brownish; cakes strongly, the best varieties forming a vitreous coke, with brilliant metallic lustre.