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124 Cdkarecus Genus. Grey, or yellowifii grey, fometimes falling into the pale yellow. It is found amorphous, or cryftallized into hexagonal prifms, terminating in an edge, or in thomboids, or cuneiform, tabular, or lenticular. In the cryftallized, the planes which form the acute angles are ftreaked longitudinally, thofe that form the obtufe are fmooth. Luftre glafly, 4, 3, 2. Tranfparency 4, 3. Fradture ftraight, or curved foliated. Hardnefs 4. Spec. gr. 2,31 r. It is often penetrated vvith fwineftor.e (as it is faid), which diminilhes its tranfparency, and gives it a difagreeable fmell when rubbed. Kärflen on Lelke, 293. Maquart, 434. It is found in great plenty, and of an extraor- cünary fize, in lluffia, if we may credit Mr. Guettard, Mem. Par. 1762, p. 861, 8vo, and Mr. Maquart, p. 403, both of whom have tra- velled into that empire: it is there ufed inilead of glafs for window panes; neverthelefs, Mr. Kärften affures us this is abfolutely falfe. Gypfum mixed with marl is often found in a flaty form. Of this fort is the fpecimen, Lelke, S. 259. Its coiour is bluiih grey, and greyifh black. I.uftre and tranfparency o. Fradture ilaty. Fragments 3. Hardnefs 7. Spec. grav. 2.473. Heated- to rednefs, it becomes reddifh white. As the fpec. grav. is fo low, I prefume the gypfum predominates. Sometimes it is mixed with the fmall foliated, as in Lelke, O. 26 j the lamellte are coarfe and more imperfedt. 11 th Speeles. Combined with the fparry acid. Fluor.