Lonsdaleite static press or using explosives. It has also been produced by chemical vapor deposition, and also by the thermal decomposition of a polymer, poly(hydridocarbyne), at atmospheric pressure, under argon atmosphere, at . It is translucent, brownish-yellow, and has an index of refraction of 2.40 to 2.41 and a specific gravity of 3.2 to 3.3. Its hardness is theoretically superior to that of cubic diamond (up to 58% more), according to computational simulations, but natural specimens exhibited somewhat lower hardness through a large range of values (from 7 to 8 on Mohs hardness scale). The cause is speculated as being due
Russellite cassiterite, topaz, muscovite, tourmaline and quartz. Russellite Russellite is a bismuth tungstate mineral with the chemical formula BiWO. It crystallizes in the orthorhombic crystal system. Russellite is yellow or yellow-green in color, with a Mohs hardness of . Russellite is named for the mineralogist Sir Arthur Russell, and the type locality is the Castle-an-Dinas Mine, near St Columb Major in Cornwall, where it was found in 1938 in wolframite. It occurs as a secondary alteration of other bismuth bearing minerals in tin - tungsten hydrothermal ore deposits, pegmatites and greisens. It typically occurs associated with native bismuth, bismuthinite, bismite, wolframite,