EARTHS. ARGILLACEOUS. 35. Ardefia. 123 



35. ARDESIA. Confiftlng of alumina and filica, 

 with generally a liccle oxyde of iron and carbo- 

 nate of lire, r.nd fomerliries fome magnefia and 

 ptrcroleum : foft, of a flaty texture, generally 

 breaking into dilcoid fragnnents, opake, of a 

 comaion form, imbibing waeer, but fo {lowly as 

 not to be foftened, when moiftened exhaling an 

 argillaceous odour: not efTcrvelcing with nitric 

 acid, melting into a turbid fcoria by a confider- 

 able degree of heat ; found in primitive as well 

 as flratified miountains, and when in the former 

 of a greafy iuftre ; forming entire mountains or 

 their principal part, 



Kovacula, A little polifhed, (hinlng \\hhin, fubopake, hardifli, green- 

 i(h-grey, making a whitilh mark. 



Schiitus Icript. alba, ^y t nut. xii. 3. />. 37. «. I ? 



N Vcicuiite, Turkey hone. Kirnvan mineral, i. p. 238. 



Whetilone. Schmei/Jer mineral 1. p. 174.. 



Found in fliillofe mountains, forming confiderabTe layers, 

 chit fly in the l^vt^ftt rear Laueitein in Bareith, Siber^at and 

 neat Frieburg in Saxony : fradlure Haty, approaching to fhi- 

 very ; does not adhere ro the tongue ; receives an imptrfedl 

 polifh, hardens in the air and in oil, and when faturated with 

 the latter makes an excellent whellone, 



tahulari', A little poliflied, foft, greyifh-black, making a whitifli 

 mark, with ftraight foliations. 

 Schiftus labularis. SjjL «a/. xii. 3. />« 37. «. 2, 

 Schiilus fubtiliorniger. Wall Jy it. \, /. 33^). «. i. 

 Found in S'witzerlandy Hungary, Franconia^ and Saxony : ad- 

 mirs an imperfeft polifh, and is fometimes variegated with 

 darker orbicular or oblong fpots; when powdered efFervefces 

 in a very flight degree with nitric acid : is rather light, and is 

 ufed foi tables and flares. 



Ugularis^ A little polifhed, rather hard, blueilli-black with a cinC" 



reous ftreak, with ftraight foliations. 

 Schiilus Ardefla. Syst. nat. xii. 3.^. 38. «. 5, 

 Schiilus durus. Wall. Cyst. min. 1 . />, 336. «. 1. 

 Argillite, Argillaceous Sbiftus, Slate. Kir<njan min,\. p,\6i» 

 Argillaceous Shillus, SchmeiJJer miner aL \.p. 168. 

 Argillaceous Shillus. Thomjon chem. 3. ^. 587. 



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