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Novaculits 239 Found in large maffes. I.uftre, o, 1. Tranfparency, 1 or 1,5. , Fraclure, flaty, but inclining ftrongly to the fplintery; fometimes alfo to the conchoidal, and earthy. Hardnefs, from 7 to 8, rarely 9. Sp. gr. from 2,609 to 2,955, kymytrial. According to Brif- fon, honc-flones for razors of a dirty white abforb water, before abforption the fp. gr. of one of thetn was 2,8763, and after abforption 2,8830; fo that it ablbrbed T ‘-. of its weight. He men- tions another whofe fp. gr. was 3,1398, whofe co- lour was black and white. Some feel fomewhat greafy. Effervefce flightly with acids ; and fome not. There are other ftones alfo ufed as hones, as fome argillites and fandftones; t'nefe laft form the coarfer whet-ftones. Some at leaft are decompofed by expofurc to the atmofphere, and form a white earth. From ail this it appears that this Species con- tains many varieties of compofition. I fhall hcre mention a few of thofe varieties I have met with. 1 It, I hat of Lelke O. 976, whofe colour is mountain green. Hardnefs 7, Sp. gr. 2,722, and does not effervefce with acids, melted at 120° into a fomewhat porous hard greyifh black, porcelain mafs, whofe furface was vitrified. 2d, Another which I bought in London: could not hcar whence it came; but it is ufed for letting razors; was of a greyifh yellow colour. Luftre, o. Tranfparency, 1,5. Fradfure fplin tery. Fragments, 1. Hardnefs from 7 to 8. Sp. gr. 2,609. And effcrvefces very flightly with acids.