Explanation
Also known as Langsdale, it belongs to the hexagonal crystal system. Uniaxial positive light, birefringence, refractive index 2.41-2.42, theoretical density 3.51g/cm3, the same as diamond. Its hardness is close to that of diamond, but its brittleness is large and its particle size is fine. The pressure of more than 13GPa and the temperature of more than 1000 ° C along the C axis of graphite can be applied by explosion or static pressure to make graphite transformation into hexagonal diamond. In some meteorites in nature, a small amount of hexagonal diamond is found to coexist with diamond. The crystalline graphite can also be transformed into hexagonal diamond by a strong quenching method.
Classification
Inorganic non-metallic materials -> Crystal growth and crystal materials