*70 EARTHS. SILICEOUS. 56. Chalcedonius. 
Found in ^lexica-, Ceylon, S-ivet^en, Bohemia, Saxony, and oth^^ 
pans of Europe, in veins of primitive rocks, and foraetimes i'’ 
agate balls and kidneys in porphyry: colour violct-bl us i” 
various degrees of intenfity. fometimes greenifh, rare'y 
white: texture concholdal, fibrous, granular, orfplintery! 
luHre various degrees of t'anfparency to nearly opake : cryl' 
tals fimple 6-fided pyramids, or with faces of different fizcs< 
the p's-'es of which are fmooth: yields to the file, is brictle» 
and eafily frangible : fpecific gravity 2.750, contains fills* 
97,50. alumina 0,25. oxyde of iron with a trace of mang*' 
nefe 0.50. Rofe, 
P^eudoetys- Qpake, in a 6-fidc(j prifm terminatine at one or both end* 
in a 6-fided pyramid. 
Nitrum opacum. Syli, nat xii. 3./ 85. ». 3. 2. 
Quartzum rude. Wall, fin i p. 216. ». 8. 
Found in Hungary, Bohemia, Saxony, Sojoeden^ and Barbary: th* 
cryftals fometimes detached, fometimes united : colour vad' 
0U3 degrees of white, black, red, or variegated. 
56. CHALCEDONIUS. Confiding of filica, * 
fmall quantity of alumina with fometimes about 
a tenth of lime, and a flight trace of oxyde u* 
iron: hard, lightifh, Ihining within, breaking into 
indeterminate fragments with fiiarp edges, cofO' 
pad, not mouldering in the air, of a more or lel® 
perfedly conchoidal texture, never opake, toughr 
admitting a high polilh, and generally of a coO*' 
mon form: not melting before the blowpipe. 
Cachtknius Milk-white, fomewhat diaphanous, becoiiiing opake i** 
the fire. 
Achates opalina. Wall. fyst. l. n, 13. 
Kachelony. Cronst. mineral. /eh. 57. 3. a. 
Cacholony. SHmeiJfer mineral, i.p 106. 
. Found in the rivers Bucharejt and N>ongool, and the Feroe ijlandst 
where it lies between the Itrata of feniitranfpai ent Chalcedony- 
It is never found in drops or Ihiafluical. The Kalmu*^* 
make their idols and domeftic veU'cls of it, 
genuinus. Grey, of a flat texture and common form, not falliuS 
fpontaneoufly into fragments. 
Silex vagus. Syst. nat. xii. 3. p. 69. n. 8. 
Achates. Wall fifi.min, I, p. 275. n. 15. 
Calcedony. Kiryuan I.p. 297, Schmeijjer min.x, p. 105. 
Chalcedony. Thom/an them. i. p.^y:,. /ame/on. \. p, 
