12z Calcareous Genus. The fpecimen, Lelke, O. 1551, is hard as 6 or 7. Spec. grav. 2,939. It is faid that it is in- tiroately mixed with l'wine-ftone; but this does not explain the reafon of its remarkable denfity ; perhaps it contains ftronthian inftead of, or with,- common calx ; but as it does not effervefce with acids, this is alfo doubtful. 3d Family. Fibrous, or ßriated. White, or greyilh, yellowilh, or reddifh white, often grey or flefh red, or honey yellow. Some- times thefe colours hieet in flripes. Luftre 2, 3. Tranfparency 2* 1, 3. Fraäure fine or coarfe, fibrous or llriated, the fibres, &c. generally ftraight and parallel, yet fometimes bent. Fragments long fplintery Hardnefs 4, brittle. Spec. grav. 2,300. Does not decrepitate when heated; never effer- vefces with acids ; when poliihed, becomes iridef- cent, 1 ( Raab, 346. The fpecimen in Lelke, O. 966. is much har? der; it does not yield to the nail. 4th Family. . Foliated. Of this there are two varieties, the fmall grained and fparry, and broad foliated. lft Va-