EARTHS. ARGILLACEOUS. 39. Opalus. 133 



ligneuf. Nearly opake, breaking longitudinally into fibrous frac- 

 tures, fpontaneoully falling into cruilofe frag- 

 ments. 



Ligniform Opal. Kirnvan mineral. I..^, 295. 



Wo'fdOpal. Schmr.£er nvner. 1, p. 145. 



Wood Opal, Thof/ijln cbem. 3. /». 524, 



Found in Hungary^ in large niiifTes which have the form of 

 wood, of a milk rcddifli or yellowifh-whirc, brown, or 

 hyacinth colour: has a ihining lurfacc, and is gevicraliy 

 femitranfparei.t on the er'ges: fradurp when broken tranf- 

 verfely conchoidal, when broken longitudinally exhibiting 

 the texture of wood : is very brittle, and confidered as 

 fragments of wood impregnated with fc;miopal. 



aereus^ Scmitranfparent, light, yellow, of a perfe<3:ly conchoidal 



texture. 



Werner Ct on/}, mineral, 55 ^.121. 



Found in Poland and Hungary^ in rounded fragmenr?, and 

 often imbedded in jafper and indurated clay : it? colciur is 

 fjmetimes a waxe'.-;, frnneiimes a honey-yeiiow, frtc^uently 

 verging to brown; it is biittie, fhining very much ir.terr 

 nally, and breaks into acute and often nearly dilcoid tsv.g- 

 nients. 



^ilior, flard, lightifh, eafily braking into ncutc fragments. 



Semi Opal. Kirivan mineral, l.p. 290. 

 Hslb Opal. Schmeifier wineraL l.p. I44» 

 Semi-opal, Menilites. T'l;ofn/on chem, ^- p- ^z^. 

 Found in Poland f Bohemia^ himgary^ ./luflria. Saxony and Ger- 

 many: colour various lliadcs of white, grey, yellow, led, 

 brown, often mixed together : diaphanous, or opake, rarely 

 iranfparent; texture more or lefs perfedly conchaceous, ^nd 

 jts luftre more or kfs glaffy: is very brittle, and lometimee 

 adheres to the tongue : fpecific gravity 2,540. contains fi- 

 lica 85,5. oxyde of iron 0,5, water 1 1,0. alumina 1,0. iime 

 0,3. Klaproth. 



%fulgarh. Reflecting a diiferent colour according to its pofition ns to 

 light, hardifh, li^htiih, diaphanous, breaking iiUQ 

 rather cbtufe fragments. 



Silex v?.gu?. Syst. nat xii. 3. /». 68. », 6. a. 



Achates fere pellucida, VFail fyft. l.p. 2^0. n. 19. 



Vulgar Opal, Kirivan mine*al. l.p. 289, 



Common Opal. Schmeij:.er miner. i./>. 141* 



Common Of al. Ihompn chem. 3. p. 522. 



Found in Poland^ Sile/ta) SaxonVy Hungary^ and Ger/7j<:nVy ufii::^!ly: 

 imbedded in otbcr ftenes, of a common form, rarely kiu^eyr 

 form or botryoidal, Hiihin!? a little internally, generally fub.- 

 e^^akc: colour white, yellow, red, green of vaaous mixtur(js;^ 



