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????? ??? ????? ???? ???? ??????. ??? ?????? ????? ????? ?? ??? ????, ??????? ?????? ?? ???? basalt. ??? ??? ???? ?????? ???? ?????? ??? ?? ??????, ???? ????? ???? ?????? ??? ?? ????? ?????. ??????? ?? ????? ?? ?? ???? Mohs ??? ????? 5-7 ?????? SiO2 ????? ?-45%-52%. ???, ?????? ?????????? ??????, ????? ?????? ???? ??????, ???? ??? ??????? ???? ????? ?????? ??????? ?????? ???? ???? ???????.
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