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Today this tourmaline locality (type locality for dravite) at Dobrova (near Dravograd), is a part of the Republic of Slovenia. [9] Tschermak gave this tourmaline the name dravite, for the Drava river area, which is the district along the Drava River (in German: Drau, in Latin: Drave) in Austria and Slovenia.
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.
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.
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Optical properties of common minerals Name Crystal system Indicatrix Optical sign Birefringence Color in plain polars Anorthite: Triclinic: Biaxial (-) 0.013
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Spodumene is a pyroxene mineral consisting of lithium aluminium inosilicate, Li Al(Si O 3) 2, and is a commercially important source of lithium.It occurs as colorless to yellowish, purplish, or lilac kunzite (see below), yellowish-green or emerald-green hiddenite, prismatic crystals, often of great size.
In 1912, to standardize birthstones, the (American) National Association of Jewelers (now called Jewelers of America) met in Kansas and officially adopted a list. [1]: 317 The Jewelry Industry Council of America updated the list in 1952 [3]: 311 by adding Alexandrite for June, citrine for November and pink tourmaline for October.