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PITCHSTONE. 277 through Several varieties of green, into brown, yellow, and red; yellow and blue are the rarest colours. The green colours are blackish-green, mountain-green, leek- green, olive green, and oil-green. From blackish-green it passes into greenish-black, bluish-black, greyish-black, ash-grey, smoke grey, and a colour intermediate between indigo and Berlin blue: from olive-green and oil-green into liver brown, reddish-brown, and pale blood-red. The yellowish-grey sometimes approaches to ochre-yel low. These colours are seldom bright, most generally dull and deep. The colour is in general uniform, seldom in veined, clouded, and spotted delineations. It occurs massive. Internally it is shining, sometimes passing into glisten- ing, even inclining to glimmering. The red has the feeblest, the bluish and the green the strongest lustre; and the lustre is vitreo resinous. The fracture is imperfect conchoidal *, and is some times large and tlat, sometimes small conchoidal. fiom the latter it passes into coarse-grained uneven, which some times approaches to coarse splintery, lhe conchoidal has the strongest, the splintery the weakest, lustre. It breaks into angular and sharp-edged fragments. 11 occurs sometimes in coarse, seldom in large and flat granular distinct concretions; sometimes in thick and and wedge-shaped prismatic concretions; and rarely in thick and straight lamellar distinct concretions. The surface of the distinct concretions is generally smooth ai 'd shining, and sometimes rather curved. It is generally feebly translucent; some varieties, par ticularly the black, are only translucent on the edges. S3 11 * Sonic varieties of the Arran pitchstone have a perfect anil laige con- choidnl fractu/c: this, with their lamellar concretions, distinguishes thcut from the more common varieties of this mineral.
