Setoi Opal. z 9 l Amorphous or in lharp fragments. Its luftre, 2. Glaffy. Tranfparency, 2.1.3. Its frafture conchoidal, fometimes imperfe&ly. Fragments, 3.2. Hardnets from 7 to 9. Krittle. Sp. gr. 1,7 102,118. Some adhere to the tongue by reafon of the rifts they contain; thefe admit water, and are often hydrophanous, as we fhall prefently fee. It is infufible as the former family. It diffcrs from opals always in luftre, and often in tranfparency, fraäure and hardnefs. Its tranfitions are into hornfionc, calcedony, chryfoprafium, jafper, and quartz; and, when decompofing, into porcelain clay. The femi opal of Lefke S. 658. much refem- bles flint, but does not give fire with fteel. Therc is a variety of the femi-opal called a Pyrophanes •, becaufe, Leing heated on a fpoon, it becomes tranfparent, but returns to its opake ftate when cold, as Mr. Landriani has difco- vered*. Mr. Sauifure, jun. renders common hydrophanes tranfparent, and of a topaz co- lour, when heated by digefting them in melted wax. It is faid that fome pyrophanes are found in Armenia, which are tranfparent while expofed to the fun, and opake at night f. * 1 Chy. Ami. 1791, p. 483. t 1 Chy. Ami. 1792, p. 35. 3d Family.