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OCR
282 MINERALOGICAL REMARKS. have the fame fhape as the preceding; they are generally a little bigger and harder, quite opake, of a more or lefs pale or deep brick colour, marked more or lefs with blackith fpots and ftreaks, and veined or reticulated like a gland. They fully refemble a marbled enamel, are generally on one fide more rounded, on the other more preffed (concavo-convex), and round about edged as a melted fubftance poured into fmall holes or cavities. Struck with. a fteel they give more fire than the preceding, and refift the greateft flroke of 2 hammer ; under the blow-pipe they flill more readily than the tranfparent ones change: to a pearl or whitiih colour on the furface, without great expanfion, and this fcorified furface then very eafily falls off in fcales. Such are the external qualities of thefe remarkable ftones, and of the fill more remarkable mowntain-rock in which they are included. How far the following chemical analyfıs of Mr. Lowitz, which I give in his own words, can throw light upon their remarkable properties, I leave to the decifion of others, till I (halt receive a greater provifion of them (which I am waiting for), and have it then in my power to fupply the learned of foreign countries, “ Chemical analyfis of a kind of foffil like Quartz Pebbles, with the mountain-rock in which they are found.—Thefe roundith ftones, which are given out for volcanic productions, are chiefly of the fize of a hazel nut, and have a {moky tran{parent appearance ; but there are fome which are opake, and of a liver colour {prinkled with blackifh and reddifh fpots ; they are confiderably hard, fcratch glafs 3 and 30
