EARTHS. SILICEOUS. 47. Jafpis. I55 



47. J.VSPIS. Confining of filica, a fmaller pro- 

 portion of alumina, and a fmall quantity of 

 oxyde of iroii, with generally a little rriagnefia 

 and potafs: hardifh, opake, breaking into in- 

 decernninate fragments, of a conchoidal texture, 

 lightifh, fomc-times detached, fometimes a prin- 

 cipal ingredient of ancient mountains, of a com- 

 mon form : lofing its colour in the fire. 



agyptia. Of a ddll colour, varied with differently coloured con- 

 centric (Iripes or layers, and black dendritical fi- 



gures. 



Si!ex Hjemachatcs. Sysf. nat. xii. 3. p. 68. n. 4. 



Cai!!on d' Egypte. Cronfi. min. feil. 60 6. a. 



Egyptian pebble, Kirn.v an mineral. \,p. 312. 



Egyptian Pebble. Zchmeijier miner ah I. />. 124. 



Egyptian Pebble. Thunijon chem. 3. ^.532. 



Found nc'ar Suez, in Egyp'^ and fometimes in Huv^ary, generally 

 in longifh oval flattifh pebbles, and enveloped in a coarfe 

 rough cruft: colour a liver-hrovvn, glittering when broken, 

 the fr pigments irregulaily angular and opake, and taking a fine 

 polifh ; the concentric ftripcs or layers are various fhades ot 

 yellow, reddifh, green, or white, but the dots and dendri- 

 tical figures are always black : fra(fiure conchoidal : wheii 

 heated it does not decrepitate : fpecific gravity from 2,564. 

 to 2,6co. It is made into vafes, fnuff-boxes, and other 

 ornaments. 



fasciata. In differently coloured alternate parallel layers, without 



luftre internally, ot an imperfedlly conchoidal tex- 

 ture. 

 Jafpis variegata. WalLfyit. min. i. p. 301. », 2. I. 

 Ribband Jalper. Schmijjer tniner. \. p. \z^. 

 Striped Jafper, Kirtvan. 1. />. 31 2. TbomfonChen;, 3. p^ 532, 

 Founa in ISiberia, in Saxony near Gyiantjiein and IVoiftitZy and 

 particularly fine at Uralj in large amorphous mafles forming 

 long layers: colours yellowifh, greenifh-grey, ochraceous, 

 ifabella yellow, brownifh-red, pale or dark fiefh-red, moun- 

 tain or dark green, generally difpjfed in parallel layers 

 >vhich arc commonly ilraight, rarely curved, feldomer in 

 oblong fpots : when broken it exhibits a dull imperfectly 

 conchoidal furface, and is fometimes femitranfparent on the 

 edge.'- : it takes a hi^h polifh : fpecific gravity from 2^500. 

 to 2,820. 



U 2 



