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Another highly valuable variety is chrome tourmaline, a rare type of dravite tourmaline from Tanzania. Chrome tourmaline is a rich green color due to the presence of chromium atoms in the crystal. Of the standard elbaite colors, blue indicolite gems are typically the most valuable, [32] followed by green verdelite and pink to red rubellite. [33]
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. [4] Notable countries where rubellite can be mined include Afghanistan, Brazil, Madagascar, Myanmar, Nigeria, Russia, and the United ...
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.
This is a list of gemstones, organized by species and types. Minerals ... Tourmaline subgroup: Achroite (var.) Chrome (var.) Dravite; Elbaite; Fluor-liddicoatite;
Elbaite, a sodium, lithium, aluminium boro-silicate, with the chemical composition Na(Li 1.5 Al 1.5)Al 6 Si 6 O 18 (BO 3) 3 (OH) 4, [4] is a mineral species belonging to the six-member ring cyclosilicate tourmaline group. Elbaite forms three series, with dravite, with fluor-liddicoatite, and with schorl.
The basic level of definition is that of mineral species, each of which is distinguished from the others by unique chemical and physical properties. For example, quartz is defined by its formula , SiO 2 , and a specific crystalline structure that distinguishes it from other minerals with the same chemical formula (termed polymorphs ).
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]
Nevertheless, diamonds, rubies, sapphires, and emeralds still have a reputation that exceeds those of other gemstones. [26] Rare or unusual gemstones, generally understood to include those gemstones which occur so infrequently in gem quality that they are scarcely known except to connoisseurs, include andalusite, axinite, cassiterite ...