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Moissanite (/ ˈ m ɔɪ s ə ˌ n aɪ t /) [5] is naturally occurring silicon carbide and its various crystalline polymorphs. It has the chemical formula SiC and is a rare mineral , discovered by the French chemist Henri Moissan in 1893.
In order to be considered for use as a diamond simulant, a material must possess certain diamond-like properties. The most advanced artificial simulants have properties which closely approach diamond, but all simulants have one or more features that clearly and (for those familiar with diamond) easily differentiate them from diamond.
As a gemstone used in jewelry, silicon carbide is called "synthetic moissanite" or just "moissanite" after the mineral name. Moissanite is similar to diamond in several important respects: it is transparent and hard (9–9.5 on the Mohs scale, compared to 10 for diamond), with a refractive index between 2.65 and 2.69 (compared to 2.42 for diamond).
Lab-grown diamonds of various colors grown by the high-pressure-and-temperature technique. A synthetic diamond or laboratory-grown diamond (LGD), also called a lab-grown diamond, [1] laboratory-created, man-made, artisan-created, artificial, synthetic, or cultured diamond, is a diamond that is produced in a controlled technological process (in contrast to naturally formed diamond, which is ...
Jewellery where pyrite is used as the gemstone is called marcasite jewellery; a term which pre-dates the scientific definition, using the original sense of the word. Marcasite in the scientific sense is not used as a gem due to its brittleness.
Reportedly, it took IAEA officials only a matter of hours to determine that these documents were fake. IAEA experts discovered indications of a crude forgery, such as the use of incorrect names of Nigerien officials. As a result, the IAEA reported to the U.N. Security Council that the documents were "in fact not authentic". The UN spokesman wrote:
Very low concentrations of the heaviest lanthanides in monazite justified the term "rare" earth for these elements, with prices to match. Thorium content of monazite is variable and sometimes can be up to 20–30%. Monazite from certain carbonatites or from Bolivian tin ore veins is essentially thorium-free. However, commercial monazite sands ...