The gangue is quartz, chlorite, tourmaline, and sometimes decomposed granite and fluor spar.
Next the metal is covered with a very basic slag, made by melting lime with a little silica and fluor spar.
This happens, for example, when green crystals of fluor spar afford blue reflections of light.
The gangue or vein-rock in which the metal is found may be calcite or calc spar, fluor spar, heavy spar or baryta, or quartz.
Cassiterite goes with boron and tourmaline, topaz, fluor spar and lithia-mica; all containing fluorine.
A transparent to translucent mineral occurring in many colors, especially yellow and purple, and usually in cube-shaped crystals with octahedral cleavage. It is found in sedimentary rocks and in ore deposits within igneous rocks. It is often fluorescent in ultraviolet light. Chemical formula: CaF2.