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( 5°9 ) ADDITION. P. 172.—Species 20. Baikalite. Its colour, olive green. Cryftallized in quadrangular, hexangular, or o&ohtedral prifms, terminated with an oblique pyramid; the odtangular have four broad, and four narrow lides. From two to ten inches long, and from half an inch to four inches thick. Sur- face fmooth, feldom longitudinally flreaked. Luftre 1.2. Rather greafy ; often in fome po- fitions mutably relplendent. Tranfparency, 0.1. Fradture, fplintery, paffing into the conhcoidal. Fragments, 2.3. Hardnefs, 8 9. Specific gra- vity, 2,200. Gives a white ftreak. üoes not effervefce with acids, except fome calcareous particles be contained in the rifts. When heated, it lometimes reddens, and at laft niclts into a dark green glafs. By the analyfis of Mr. Lowitz, it contains 0,44 filex 0,30 magnefia, 0,20 calx, 0,06 calx of iron,’ and, cafually, fluor acid. This ftone has as yet bcen found only on the borders of the lake Baikal, in Siberia, from which it derives its name *. Some have called it * 7 Chy. Amial. 1793, u. 5 Crell Beytr. 4 Stuk 407. 2 ß°''h