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Lonsdaleite (named in honour of Kathleen Lonsdale), also called hexagonal diamond in reference to the crystal structure, is an allotrope of carbon with a hexagonal lattice, as opposed to the cubical lattice of conventional diamond.
Lonsdaleite is an allotrope sometimes called "hexagonal diamond", formed from graphite present in meteorites upon their impact on the earth. The great heat and pressure of the impact transforms the graphite into a denser form similar to diamond but retaining graphite's hexagonal crystal lattice. "Hexagonal diamond" has also been synthesized in ...
Amethyst crystals – a purple quartz Apophyllite crystals sitting right beside a cluster of peachy bowtie stilbite Aquamarine variety of beryl with tourmaline on orthoclase Arsenopyrite from Hidalgo del Parral, Chihuahua, Mexico Aurichalcite needles spraying out within a protected pocket lined by bladed calcite crystals Austinite from the Ojuela Mine, Mapimí, Durango, Mexico Ametrine ...
From theoretical considerations, lonsdaleite is expected to be harder than diamond, but the size and quality of the available stones are insufficient to test this hypothesis. [9] In terms of crystal habit , diamonds occur most often as euhedral (well-formed) or rounded octahedra and twinned , flattened octahedra with a triangular outline.
The more common one uses a cubic lattice, while the less common one, lonsdaleite, has a hexagonal lattice. By mixing these polytypes at the nanoscale, DLC coatings can be made that at the same time are amorphous, flexible, and yet purely sp 3 bonded "diamond". The hardest, strongest, and slickest is tetrahedral amorphous carbon (ta-C). [3]
This list includes those recognised minerals beginning with the letter L.The International Mineralogical Association is the international group that recognises new minerals and new mineral names; however, minerals discovered before 1959 did not go through the official naming procedure, although some minerals published previously have been either confirmed or discredited since that date.
Lonsdaleite is part of WikiProject Rocks and minerals, an attempt at creating a standardized, informative, comprehensive and easy-to-use rocks and minerals resource. If you would like to participate, you can choose to edit this article, or visit the project page for more information.
Lonsdaleite, an allotrope of carbon, was named in her honour; it is a rare harder form of diamond found in meteorites. [46] [47] Several universities have buildings named in her honour including at University College London, at the University of Limerick, [48] and at Dublin City University, [49] and Maynooth University.