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There are over 300 types of minerals that have been used as ... Rock crystal (var.) Shocked quartz (var.) Smoky ... Gemstones of the World revised 5th edition, ...
As of 1999, the world's largest known naturally occurring crystal is a crystal of beryl from Malakialina, Madagascar, 18 m (59 ft) long and 3.5 m (11 ft) in diameter, and weighing 380,000 kg (840,000 lb). [12] Some crystals have formed by magmatic and metamorphic processes, giving origin to large masses of crystalline rock.
Differences in chemical composition and crystal structure distinguish the various species. Within a mineral species there may be variation in physical properties or minor amounts of impurities that are recognized by mineralogists or wider society as a mineral variety. Mineral variety names are listed after the valid minerals for each letter.
Minerals are distinguished by various chemical and physical properties. Differences in chemical composition and crystal structure distinguish the various species. Within a mineral species there may be variation in physical properties or minor amounts of impurities that are recognized by mineralogists or wider society as a mineral variety.
Many gems are crystals which are classified by their crystal system such as cubic or trigonal or monoclinic. Another term used is habit, the form the gem is usually found in. [12] For example, diamonds, which have a cubic crystal system, are often found as octahedrons. [13] Gemstones are classified into different groups, species, and varieties.
This crystal structure is based on regular internal atomic or ionic arrangement that is often expressed in the geometric form that the crystal takes. Even when the mineral grains are too small to see or are irregularly shaped, the underlying crystal structure is always periodic and can be determined by X-ray diffraction. [ 13 ]
Max von Laue (1879–1960): diffraction of X-rays by crystals (1912). Arthur Moritz Schoenflies (1853–1928) und Evgraf Fedorov (1853–1919): characterisation of all 230 crystal space groups (1890/91). William Lawrence Bragg (1890–1971) and William Henry Bragg (1862–1942): law on the diffraction of X-rays by crystals (1912). They are ...
Samarian Spinel, the world's largest spinel; Menshikov Ruby, the world's second largest spinel set on top of the Great Imperial Crown of Russia; Timur Ruby, believed to be a ruby until 1851, hence its name; Black Prince's Ruby, the famous spinel mounted on the Imperial State Crown of the United Kingdom