Biotites occurring in igneous and metamorphic-metasomatic rocks have been critically studied. The study reveals a marked difference between the chemical composition of biotites from igneous rocks on one hand and those from metamorphic-metasomatic ones on the other. It is concluded that the chemical composition of a biotite reflects the environment of its formation as well as that of t... https://chefesquipmenters.shop/product-category/side-chairs/