EARTHS., argillaceous. 35. Ardefia. 
123 
35. ARDESIA. Confiding of alumina and filica, 
\vith generally a little oxyde of iron and carbo- 
nate of litre, and fometimes fome magnefia and 
petroleum: folt, of a flaty texture, generally 
breaking into difcoid fragments, opake, of a 
common form, imbibing waeer, but fo (lowly as 
not to be fcfcened, when moifiened exhaling an 
argillaceous odour ; not cffcrvcfcing with nitric 
acid, melting into a turbid fcoria by a confider- 
able degree of heat; found in primitive as well 
as ftratified mountains, and when in the former 
of a greafy luftre ; forming entire mountains or 
their principal part. 
A little polKhed, fltining within, fubopake, iiardifli, green- 
ifii-grey, making a whitilli mark. 
Schilhisicript. alba. Ajit. na/. xii. 3. p. 37. n. J? 
N’: vacitlite, Turkey hone. Kimvan mineral. \.p. 238. 
Whctllonc. Schmci(;er mineral. )./. 174. 
Found in fiiiilofe mountains, iormipg eonfiderabic layers, 
chiefly in the Le-vai.t, near Laueilein in Bareith, Siberia, and 
neat Fiifburg in Saxony ; fraAtire flaty, approaching to Ihw 
very ; does not adhere to the tongue ; receives an imperteft 
polifli, hardens in the air and in oil, and when (aturated with 
the latter makes an excellent wheftonc. 
A little poliflicd, foft, greyifli-black, making a whitifh 
mark, with (Iraight foliations. 
Schiftus labuliiis. Syji. nnt. xii. 3. p. 37. n. 2, 
Kchiflus fubiilior niger. Wall Jyit. 1. 33 ^- »• > • 
Found xvi Svjitxxrland, Hungary, Francome, and Saxony: ad- 
mits an imperfea poJifli, and is fometimes variegated with 
darker orbicular or oblong fpots; when powdered eftervefees 
in a very flight degree with nitric acid ; is rather light, and is 
uied foi tables and flrtes. 
‘‘ixiaris, A little polifhed, rather hard, hi ueilh- black with a cine- 
reous ftreak, with (Iraight (oliations. 
Scl'illus Ardefia. Syst. vat. xii. 3. p- 3 ^ 5 " 
Schillus durus. Wall. fy‘*- i. p. 33 °' 
Argillite, Argillaceous Shiftuf, Slate. Kirrj:anmin.\.p.\t%. 
Argillaceous Shiftus. SchmeiJjer emneral. \.p. 168. 
Argillaceous Shiflus. Thomjon chem. 3. p. 587. 
Q 2. 
