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Tourmaline
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== Species and varieties == Commonly encountered species and varieties of tourmaline include the following: * Schorl species ** Brownish-black to black—{{em|schorl}} * Dravite species (from the Drave district of [[Carinthia (state)|Carinthia]]) ** Dark yellow to brownish-black—{{em|dravite}} * [[Elbaite]] species (named after the island of [[Elba]], [[Italy]]) ** Red or pinkish-red—{{em|[[rubellite (gem)|rubellite]]}} variety ** Light blue to bluish-green—{{em|indicolite}} variety (from ''[[indigo]]'') ** Green—{{em|verdelite}} variety ** Colorless—{{em|achroite}} variety ({{etymology|grc|''{{wikt-lang|grc|άχρωμος}}'' ({{grc-transl|άχρωμος}})|colorless}}) === Schorl === [[File:Fluorite-Foitite-Schorl-k-117a.jpg|thumb|left|A single stark green fluorite isolated on top of schorl crystals]] [[File:Tourmaline noire ou Schorl.jpg|thumb|upright|Schorl, magnified 10×]] The most common species of tourmaline is {{em|schorl}}, the sodium iron (divalent) endmember of the group. It may account for 95% or more of all tourmaline in nature. The early history of the mineral schorl shows that the name "schorl" was in use prior to 1400 because a village known today as [[Zschorlau]] (in [[Saxony]], Germany) was then named "Schorl" (or minor variants of this name), and the village had a nearby [[tin]] mine where, in addition to [[cassiterite]], black tourmaline was found. The first description of schorl with the name "schürl" and its occurrence (various tin mines in the [[Ore Mountains]]) was written by [[Johannes Mathesius]] (1504–1565) in 1562 under the title "Sarepta oder Bergpostill".<ref name="Ertl 2006">Ertl, 2006.</ref> Up to about 1600, additional names used in the [[German language]] were "Schurel", "Schörle", and "Schurl". Beginning in the 18th century, the name ''Schörl'' was mainly used in the German-speaking area. In English, the names ''shorl'' and ''shirl'' were used in the 18th century. In the 19th century the names ''common schorl'', ''schörl'', ''schorl'' and ''iron tourmaline'' were the English words used for this mineral.<ref name="Ertl 2006" /> === Dravite === [[File:Black Dravite, Yinnietherra, Western Australia.jpg|thumb|left|Black dravite on a grey matrix]] {{em|Dravite}}, also called {{em|brown tourmaline}}, is the sodium magnesium rich tourmaline endmember. Uvite, in comparison, is a calcium magnesium tourmaline. Dravite forms multiple series, with other tourmaline members, including schorl and elbaite.<ref>{{Cite web|title=What is Tourmaline? – GIA|url=https://www.gia.edu/tourmaline}}</ref> The name ''dravite'' was used for the first time by [[Gustav Tschermak von Seysenegg|Gustav Tschermak]] (1836–1927), Professor of [[Mineralogy]] and [[Petrography]] at the [[University of Vienna]], in his book ''Lehrbuch der Mineralogie'' (published in 1884) for [[magnesium]]-rich (and [[sodium]]-rich) tourmaline from village Dobrova near [[Dravograd|Unterdrauburg]] in the [[Drava]] river area, [[Duchy of Carinthia|Carinthia]], [[Austria-Hungary|Austro-Hungarian Empire]]. Today this tourmaline locality (type locality for dravite) at Dobrova (near [[Dravograd]]), is a part of the [[Slovenia|Republic of Slovenia]].<ref name="Ertl 2007">Ertl, 2007.</ref> 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. The chemical composition which was given by Tschermak in 1884 for this dravite approximately corresponds to the formula {{chem2|NaMg3(Al,Mg)6B3Si6O27(OH)}}, which is in good agreement (except for the [[hydroxide ion|OH]] content) with the endmember formula of dravite as known today.<ref name="Ertl 2007" /> Dravite varieties include the deep green chromium dravite and the vanadium dravite.<ref>{{Cite web|title=Tourmaline Information – Gemstone Education|url=https://www.starlanka.com/gemstone-education/tourmaline-stone/}}</ref> === Elbaite === {{Main|Elbaite}} [[File:Elbaite-Lepidolite-Quartz-gem7-x1a.jpg|thumb|Elbaite with quartz and lepidolite on cleavelandite]] A lithium-tourmaline [[elbaite]] was one of three pegmatitic minerals from [[Utö, Sweden|Utö]], [[Sweden]], in which the new alkali element [[lithium]] (Li) was determined in 1818 by [[Johan August Arfwedson]] for the first time.<ref name="Ertl 2008">Ertl, 2008.</ref> [[Elba|Elba Island]], [[Italy]], was one of the first localities where colored and colorless Li-tourmalines were extensively chemically analysed. In 1850, [[Karl Friedrich August Rammelsberg]] described [[fluorine]] (F) in tourmaline for the first time. In 1870, he proved that all varieties of tourmaline contain chemically bound water. In 1889, Scharitzer proposed the substitution of (OH) by F in red Li-tourmaline from [[Sušice]], [[Czech Republic]]. In 1914, [[Vladimir Vernadsky]] proposed the name ''Elbait'' for lithium-, sodium-, and aluminum-rich tourmaline from Elba Island, Italy, with the simplified formula {{chem2|(Li,Na)HAl6B2Si4O21}}.<ref name="Ertl 2008" /> Most likely the type material for elbaite was found at Fonte del Prete, San Piero in Campo, [[Campo nell'Elba]], [[Elba]] Island, [[Province of Livorno]], [[Tuscany]], [[Italy]].<ref name="Ertl 2008" /> In 1933 Winchell published an updated formula for elbaite, {{chem2|H8Na2Li3Al3B6Al12Si12O62}}, which is commonly used to date written as {{chem2|Na(Li1.5Al1.5)Al6(BO3)3[Si6O18](OH)3(OH)}}.<ref name="Ertl 2008" /> The first crystal structure determination of a Li-rich tourmaline was published in 1972 by Donnay and Barton, performed on a pink elbaite from [[San Diego County, California|San Diego County]], [[California]], United States.{{Citation needed|date=January 2021}}
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