Clinkstone. 3^* . In the great it occurs in irregular columnar and tabular diftintt concretions. Commonly tranllucent on the edges, Hard and femi-hard. Brittle. • Eafily frangible. Not particularly heavy. Specific gravity.—2,575.—Klaproth, t When ftruck with a hammer, founds like a piece °f metal. • ' ^ Chemical CharaEler. Melts eafily, and gives a nearly colourlefs glafs, whereas bafalt gives a black glals. Conjlituent Parts. Silica 57*25 Alumina ^ 2 3*J° Oxyd of iron 0 .? 2,25 Manganefe 0,45 Natron i- ‘ 8,10 Water • „ 3>°° '•> > : I yd- ,;-r! • f 98,10 r' • j Accoiding wr 3 d Gsognostic.