EARTHS. SILICEOUS. 47. Jafpis. 
*55 
47. J AS PIS. Confiding of filica, a fmaller pro- 
portion of alunnina, and a fmall quantity of 
oxyde of iron, v;ith generally a little magnefia 
and potafs: hardifh, opake, breaking into in- 
determinate fragments, of a conchoidal texture, 
lightilh, ibmetimes detached, fometimcs a prin- 
cipal ingredient of ancient mountains, of a com- 
mon form : lofing its colour in the fire. 
Of a dull colour, varied with differently coloured con- 
centric firipes or layers, and black dcndritical fi- 
gures. 
Silex Haimachates. Sysf. nat. xii. 5. p. 68. n, 4, 
Caillon d’ Egypte. CronH tain. feB. ho. 6. a. 
jEgypiian i^ebble. Ktrrvan min:‘aL i.p. 312. 
Egyptian Pebble. Schaieifier mineral. 1. p. 124. 
Egyptian Pebble. 'Thomfiti them 3. ^.532. 
Found near 5 uex in Egyp<, and fomctimjs in Hungary, generally 
in longifh oval flattifln pebbles, and enveloped in a coarfc 
rough cruft: colour a liver-brown, glittering when broken, 
the fragments irregulaily angular and opake, and taking a fine 
polifh ; the concentric ftripes or layeis are various fhades of 
yellow, reddifh, green, or white, but the dots and dendri- 
tical figures are always black ; fraflure conchoidal : when 
heated it does not decrepitate : Ipecific gravity from 2,564. 
to 2 , 6 oo. It is made into vales, fiiuff-boxes, and other 
ornaments. 
f‘*‘tiata. In differently coloured alternate parallel layers, without 
lullre internally, of an imperfedlly conchoidal tex- 
ture. 
jafpis variegata, t'P'uH, jjyit. min. i.^. 301.3. 2. I. 
Ribband jafper. Sebmeijjer miner, i.^. 125. 
Striped jafper, Earivan. i./. 31Z. IhomfinChem. 1. p. ^ 1 %. 
Found in Siberia, in S'axetn near Gnantfiein and Wclftita, and 
particularly fine at Ural, in large amorphous mafles forming 
long layers: colours yellowilli, greeniih-grey, ochraeeous, 
ifabella yellow, brovvnifh-red, pale or dark flefli -red, moun- 
tain or dark green, generally difpoied in parallel layers 
which are commonly Itraight, iirely curved, ieldomer in 
oblong fpots: when broken it exhibits a dull impcrfeftly 
conchoidal furface, and is fometimes femitranfparent on thp 
edges ; it takes a high polifh : fpecific gravity from 2,500. 
to 2,82c. 
U 2 
