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
Mineralogy have a hardness that depends significantly on direction. Hardness can also be measured on an absolute scale using a sclerometer; compared to the absolute scale, the Mohs scale is nonlinear. "Tenacity" refers to the way a mineral behaves when it is broken, crushed, bent or torn. A mineral can be brittle, malleable, sectile, ductile, flexible or elastic. An important influence on tenacity is the type of chemical bond ("e.g.," ionic or metallic). Of the other measures of mechanical cohesion, "cleavage" is the tendency to break along certain crystallographic planes. It is described by the quality ("e.g.", perfect or fair) and