VESUVIANITE
VESUVIANITE Vesuvianite – Ca10(Mg, Fe)2Al4(SiO4)5(Si2O7)2(OH,F)4 – is a sorosilicate of more restricted occurrence, typical of impure marbles that have undergone contact metamorphism. It has no economic importance beyond its occasional use as a gemstone. An old name for vesuvianite, still widely used, is “idocrase”. Vesuvianite is part of the Vesuvianite Group and is isostructural with […]
VOLCANIC GLASS
VOLCANIC GLASS Volcanic glass, also called obsidian, is a very common, amorphous material that occurs only in lavas and hypabyssal intrusive rocks (sills and dykes), as a fundamental mass and containing small crystals and phenocrysts. Its formula depends on the type of rock and is complex, very variable. 4. Transmitted Light Microscopy Refraction indices: Not […]
VAESITE
VAESITE Vaesite is a very rare sulfide, occurring in some very specific parageneses. It is not an ore. It is classified in the Pyrite Group. It is isostructural with cattierite, with which it forms a series. It may contain Co and Fe, and there is a variety with Se. Vaesite crystals appear as cubes and […]