SCHEELITE
SCHEELITE Scheelite – Ca(WO4) – is a restricted occurrence tungstate. It is, after wolframite, the second most important ore of tungsten, a strategic metal. Well-formed crystals are rare and fetch high prices among collectors. When devoid of inclusions, it can be used as a gem. Scheelite can be synthesized in laboratory (Czochralski process) and has […]
SANIDINE
SANIDINE Sanidine – (K,Na)(Si,Al)4O8 – is a common tectosilicate, a high-temperature potassium feldspar typical of volcanic and hypabyssal rocks. Only the rare colored varieties have any economic importance. High-temperature sanidine (“high sanidine”) is stable at temperatures above 800°C and low-temperature sanidine (“low sanidine”) is stable between 650 and 800°C. Below 650ºC, orthoclase and microcline are […]