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
Topaz these translations as "topaz" all derive from the Septuagint translation "topazi[os]", which as mentioned above referred to a yellow stone that was not topaz, but probably "chrysolite" (chrysoberyl or peridot), it should be borne in mind that topaz is likely not meant here. An English superstition held that topaz cured lunacy. Topaz Topaz is a silicate mineral of aluminium and fluorine with the chemical formula AlSiO(F, OH). Topaz crystallizes in the orthorhombic system, and its crystals are mostly prismatic terminated by pyramidal and other faces. It is one of the hardest naturally occurring minerals (Mohs hardness of 8) and is