Lonsdaleite (named in honour of Kathleen Lonsdale), also called hexagonal diamond in reference to thecrystal structure, is an allotrope of carbon with a hexagonal lattice. In nature, it forms when meteoritescontaining graphite strike the Earth. The great heat and stress of the impact transforms the graphite into diamond, but retains graphite's hexagonal crystal lattice. Lonsdaleite was first identified in 1967 from the Canyon Diablo meteorite, where it occurs as microscopic crystals associated with diamond [1][2]
A simulated pure sample has been found to be 58% harder than diamond.[11]
