188 DESCRIPTIVE MINERALOGY. 



ANTHRACITE. 



[From the Greek av^pa|, carbon.] 



Anthracite. Haiy, Cleaveland, Phillips, Ttomson and Beudant. — Non-Bituminous Mineral Coal, Glance Coal, 

 Blind Coal, Kilkenny Coal. Jatneson. — Harzlose Stein-Kohle. Mohs. 



Description. Colour black, sometimes with a tinge of blue, brown, or grey, and some- 

 times beautifully iridescent. It seldom exhibits any regular form, although Haiiy states that 

 he has met with it in imperfect acute octahedrons, and something of the same kind is said to 

 have been noticed in the anthracite of Pennsylvania ; it also occurs massive, vesicular and 

 disseminated. Fracture conchoidal, uneven and slaty. Lustre imperfect, metallic or silky ; 

 opaque. Hardness from 2.0 to 2.5. Specific gravity — specimen from Kilkenny, 1.435 

 {Thomson); specimens from Pennsylvania, 1.52 to 1 .55. It burns without emitting smoke, 

 and with little or no flame, and leaves a white or reddish coloured ash. 



Varieties. The several varieties which are someties known by the names of Conchoidal, 

 Slaty, Columnar, and Fibrous Glance Coal or Anthracite, differ only in the mechanical 

 arrangement of their particles. 



Composition. Anthracite, in its pure state, consists almost entirely of carbon. It usually 

 contains a small quantity of water and earthy matters, principally silica and alumina. Accord- 

 ing to the analysis of Richardson and Regnault, anthracite contains carbon 91 .98, hydrogen 

 3.92, oxygen and nitrogen 3.16, ashes 0.94. 



Geological Situation. Anthracite, like the bituminous coal, when it occurs in workable 

 beds, is found only in the secondary rocks ; but in smaller quantities, it is found in those of the 

 transition series, as will appear in the following account of our localities. It has already been 

 stated, and is but too well known, that this mineral does not occur jn large beds in the State 

 of New- York. There are, however, numerous localities in which there are found thin seams 

 and masses of sufficient size for cabinet specimens. In accordance with the plan of this work, 

 these are to be briefly noticed. 



LOCALITIES. 



Albany County. Thin seams of anthracite, of a shining black colour, have been found 

 between the layers of greywacke on the banks of the Norman's kill, about two miles south 

 of the city. 



Columbia County. The preceding remark will apply to the slate in various parts of this 

 county, which often contains thin layers of anthracite. The slate itself frequently has a black 

 glazing, which gives it the appearance of this mineral. Vast sums have been expended in 

 explorations originating in mistaken notions concerning the nature and geological position of 

 this rock. 



