Page:Transactions NZ Institute Volume 15.djvu/470

b. Brown Coal.—Rarely shows vegetable structure. Fracture irregular, conchoidal, with incipient lamination; 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.

c. 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).

a. Glance Coal.—Non-caking, massive, compact or friable; fracture cuboidal, splintery; lustre glistening or metallic; structure obviously laminated; colour black; does not form a caking coke, but slightly adheres. This variety is chiefly brown coal altered by igneous rocks, and presents every intermediate stage from brown coal to anthracite.

b. Semibituminous Coal.—Compact, with laminæ of bright and dull coal alternately; fracture irregular; lustre moderate; cakes moderately or is non-caking.

c. Bituminous Coals.—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.

Lignite.—Deposits of lignite occur widely distributed throughout New Zealand, and in Otago and Southland, as pointed out by Dr. Hector (Jurors' Rep. N.Z. Ex., 1865, p. 374); they occur scattered over the surface of the primitive slate rocks of the interior. They are of recent tertiary age, being only overlaid by the newer drifts in the form of brick clays, ferruginous gravels, silts and shingle terraces. One of the most important of these lignite deposits is that near Mataura, in Southland, where a seam from 6 feet to 20 feet in thickness is worked by a number of small open casts for the local requirements of the district, and another important deposit of a similar nature, but from 9 feet to 30 feet thick, is also worked in the interior of Otago at Naseby, Kyeburn, and Hyde. Besides these, many less important deposits of lignite occur throughout New Zealand; thus near Te Anau Lake there are seams about 2 feet thick, and throughout the Lower Waikato basin and near Raglan further deposits occur, some of the outcrops being several feet in thickness, but they are not worked owing to brown coals being more accessible and of better quality. Between