Crystal is a large, colorless and transparent quartz crystal mineral.  Its main chemical composition is silicon dioxide (SiO2). It is transparent to translucent and has vitreous luster.

 

Wolframite is the principal ore for tungsten smeltering. Wolframite is brown to black, with a metal or semi-metallic luster. It is generally found in granite and quartz deposits together with tin ore. Usually it is found in high-temperature hydrothermal quartz reef.