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TigurateTrap. ' 2 3* derived from the ftones that feil out of them. That mentioned in Lefke G. 296, had its fp. gr. 2,443, and gives a reddifh ftreak. It melted atr j o 0 ° into a black compaft glafs •, that in Lefke G. 300, had its fp. gr. 2,354, gives a white ftreak, and melts into a mafs hmilar to the for- mer. The hardnefs of both is 8. It is the porofuy of this ftonc thatrenders it fo light. Its tranfitions, and tbofe of kragg and mullen ftones that are nearly allicd to it, are into each other, or into wackcn, or argillaceous marl, or fandftone, or fhifiofe porphyry, or amygdaloid. Such of thefe ftones as are fpecifically lighter than 2,78 feem to contain wacken, or lome other of thofe fpecies, that border on the genuine traps. ad Family. Figurate Trap, Bafalt. Bafalt of Werner. Colour, greyifh black, fometimes bluifh, or brownilh black; when withered, the furface is greyifh, or reddifh brown. Found inconfiderable maffes. Luftre, properly, 0; but from fome fhining particles intermixed with it, 1. Tranlparency, o; yet fometimes in very thin pieces, 1. Frafture, compaft, moftly fine fplintery; fome times approaching to the even, or flat conchoidal. 1 Bergm. J. 1792, 300. Fragments, 2. Gensrally of a columnar form, ftreight or curved, perpendicular or inclined, rarely paraf- CL4 leli