152 EARTHS. SILICEOUS. 45. PyromachilSk 
OcdusCati. Diaphanous, of an imperfeftly foliated texture, exhibit- 
ing parallel fibres internally, breaking into fomewhat 
irregular Itagments. 
Silex Oculus Cati. Syfl. nat. xii, 3. p. 6g. n, 6. c. 
Achates plus minus opaca. Wall. jyst. l.p. 282. n. io. 
Cat’s eye. Kir-tuan miner. \ , p. 301. Schmeiffer. l.p. 137. 
Cat’s eye. Ihomfon them. 3. p, 523.. 
Found in Ceykn and Siberia, of a nearly fquare figure, with 
lharp edges and a good deal of brilliancy ; colour grey, with 
a tinge of greca, yellow or white, in certain pofitions re- 
flefting a fpiendid white like the eye of a Cat, fometiines 
brown with a yellow or red tinge: its texture rs fo compaft> 
that the foliations are hardly difcernible, and is fo hard as to 
ftrike fire with fteel ; fpecific gravity from 2,625. to *,66o» 
contains filica 94,50. alumina 2,00. lime 1,50, oxyde of 
iron 0,25. Klaproth, 
45. PVROMACHtJS. Confifting principally of 
filica, with a fmall portion of alumina and oxyde 
of iron, and frequently a little carbonate of lime: 
hard, femitranfparent, lightifli, of a conchoidal 
texture, breaking into indeterminate very acut- 
angled fragments, rarely feparating into concen- 
trically cruftole fragments, with hardly any luftre, 
found chiefly in ftratarial mountains, and rarely 
forming ftrata itfelf: not fufible per fe before the 
blowpipe. 
rincrens. Greyilli, approaching to fubopakc, and of a fomewhat 
fplintery texture. 
Silex marmoreus vagus. Syst.nat. xii. 3, p, 68. ». 3. 
Silex cinereus. It, Wgoth^ 73. 
Found detached in Luface, and on mount Moffehnrg in Wejiro‘ 
goth, covered with a hard white marmoreous cruft : it ap- 
proaches to a petrofi;ex. 
itr/atbj. White, of a texture approaching to fibrous. 
Wall. fyit. min, i. p. z66. «. 7. 
Found on the cretaceous hills of England. 
(.rctaceusi Tinged, femitranfparent, of a perfe£lly conchoidal tex- 
ture. 
Silex vagus. Syst. nat. xii. 3. p. 67, n. 1. 
Silex opacus. Wall. Jyll. min. 1. p. 262. n. 4. 
Silex communis. Cronst. tniner.bit 
