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Dravite species such as green chromium dravite and brown dravite are diamagnetic. A handheld neodymium magnet can be used to identify or separate some types of tourmaline gems from others. For example, blue indicolite tourmaline is the only blue gemstone of any kind that will show a drag response when a neodymium magnet is applied.
As a gemstone, elbaite is a desirable member of the tourmaline group because of the variety and depth of its colours and quality of the crystals. Originally discovered on the island of Elba , Italy in 1913, it has since been found in many parts of the world.
These complex pegmatites contain unusual minerals of these elements, such as beryl, spodumene, [8] lepidolite, amblygonite, topaz, apatite, fluorite, tourmaline, triphylite, columbite, monazite, and molybdenite. Some of these can be important ore minerals. [5] Some gemstones, such as emerald, are found almost exclusively in pegmatites. [8]
Rubellite is the red or pink variety of tourmaline and is a member of elbaite.Rubellite is also the rarest gem in its family. [2] It is occasionally mistaken for ruby. [3] These gems typically contain inclusions.
This is a list of gemstones, organized by species and types. Minerals There ... Tourmaline subgroup: Achroite (var.) Chrome (var.) Dravite; Elbaite; Fluor-liddicoatite;
The "chelsea" filter was originally devised by Anderson and Payne in 1934 of the Gem testing Laboratory of the London Chamber of Commerce & Industry.The filter was devised with the collaboration of gemmology students of the Chelsea College of Science and Technology where Basil Anderson was an instructor for the Gemmological Association of Great Britain.
Pleochroism is an extremely useful tool in mineralogy and gemology for mineral and gem identification, since the number of colors visible from different angles can identify the possible crystalline structure of a gemstone or mineral and therefore help to classify it. Minerals that are otherwise very similar often have very different pleochroic ...
Gemology and mineralogy are not quite in lockstep in identification. There is an official mineral board that makes nomenclature decisions; there is no equivalent in gem-land. In gemology, tourmaline is considered a species, although, as you note that is not precisely correct. A gemologist only sees elbaite, and calls it tourmaline.