Volltext Seite (XML)
210 (QUARTZ FAMILY. of intensity; it passes into light grass-green, pistachio- green, and olive-green. It occurs generally massive, and sometimes in plates. Internally it is dull; glimmering, when it inclines to opal. Its characteristic fracture is even ; some varieties run into small and fine splintery; others, very rarely, into flat conchoidal. The fragments are angular, and more or less sharp edged. It is intermediate between translucent and semi-trans" parent, but always approaches more to the first. Rather softer than calcedony and flint. Is rather difficultly frangible. Rather heavy. Specific gravity, 2.600, De la Metherie. 2.714, Kar- sten. 2.608, Hoffmann. 3.250, Klaproth. Chemical Characters. Before the blowpipe it loses its colour and transparent cy, and is infusible without addition. Constituent Parts. Silica, . 06.16 Lime, 0.83 Magnesia, 0.08 Alumina, 0.08 Oxide of iron, 0.08 Oxide of nickel, 1.00 100 Klaproth, Beit, t. ii. p. 133. Gtognostic