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Vanadio-oxy-dravite, NaV (sub 3) (Al (sub 4) Mg (sub 2) )(Si (sub 6) O (sub 18) )(BO (sub 3) ) (sub 3) (OH) (sub 3) O, a new mineral species of the tourmaline supergroup

Ferdinando Bosi, Henrik Skogby, Leonid Reznitskii and Ulf Halenius
Vanadio-oxy-dravite, NaV (sub 3) (Al (sub 4) Mg (sub 2) )(Si (sub 6) O (sub 18) )(BO (sub 3) ) (sub 3) (OH) (sub 3) O, a new mineral species of the tourmaline supergroup
American Mineralogist (January 2014) 99 (1): 218-224

Abstract

Vanadio-oxy-dravite, NaV (sub 3) (Al (sub 4) Mg (sub 2) )(Si (sub 6) O (sub 18) )(BO (sub 3) ) (sub 3) (OH) (sub 3) O, is a new mineral of the tourmaline supergroup. It is found in metaquartzites of the Pereval marble quarry (Sludyanka, Lake Baikal, Russia) in association with quartz, Cr-V-bearing tremolite and mica, diopside-kosmochlor-natalyite, Cr-bearing goldmanite, escolaite-karelianite, dravite-oxy-vanadium-dravite, V-bearing titanite and rutile, ilmenite, oxyvanite-berdesinskiite, shreyerite, plagioclase, scapolite, zircon, pyrite, and an unnamed oxide of V, Cr, Ti, U, and Nb. Crystals are green, transparent with a vitreous luster, pale green streak, and conchoidal fracture. Vanadio-oxy-dravite has a Mohs hardness of approximately 7 1/2, and a calculated density of 3.14 g/cm (super 3) . In plane-polarized light, vanadio-oxy-dravite is pleochroic (O = yellow green and E = pale olive green) and uniaxial negative: omega = 1.693(5), epsilon = 1.673(5). Vanadio-oxy-dravite is rhombohedral, space group R3m, with the unit-cell parameters a = 16.0273(3), c = 7.2833(1) Aa, V = 1620.24(5) A (super 3) , Z = 3. Crystal-chemical analysis resulted in the empirical structural formula: (sub X) (Na (sub 0.70) Ca (sub 0.23) [] (sub 0.05) K (sub 0.02) ) (sub Sigma 1.00) (super Y) (V (super 3+) (sub 1.39) Mg (sub 1.16) Al (sub 0. 35) Fe (super 3+) (sub 0.04) Ti (super 4+) (sub 0.04) Fe (super 2+) (sub 0.02) ) (sub Sigma 3.00) (super Z) (Al (sub 3.74) Mg (sub 1.28) V (super 3+) (sub 0.78) Cr (super 3+) (sub 0.20) ) (sub Sigma 6.00) (super T) (So (sub 6.00) O (sub 18) ) (super B) (BO (sub 3) ) (sub 3) (super V) (OH (sub 3) (super W) [O (sub 0.74) (OH) (sub 0.26) ] (sub Sigma 1.00) . The crystal structure of vanadio-oxy-dravite was refined to an R1 index of 1.70% using 1800 unique reflections collected with MoKalpha X-radiation. Ideally, vanadio-oxy-dravite is related to oxy-dravite and oxy-vanadium-dravite by the homovalent substitution V (super 3+) <--> Al (super 3+) . Tourmaline with chemical compositions classified as vanadio-oxy-dravite can be either Al dominant or V dominant as a result of the compositional boundaries along the solid solution between Al and V (super 3+) that are determined at (super Y+Z) (V (sub 1.5) Al (sub 5.5) ), corresponding to Na (super Y) (V (sub 1.5) Al (sub 1.5) ) (super Z) (Al (sub 4) Mg (sub 2) )Si (sub 6) O (sub 18) (BO (sub 3) ) (sub 3) (OH) (sub 3) O, and (super Y+Z) (V (sub 5) Al (sub 2) ), corresponding to Na (super Y) (V (sub 3) ) (super Z) (V (sub 2) Al (sub 2) Mg (sub 2) )Si (sub 6) O (sub 18) (BO (sub 3) ) (sub 3) (OH) (sub 3) O.


ISSN: 0003-004X
EISSN: 1945-3027
Coden: AMMIAY
Serial Title: American Mineralogist
Serial Volume: 99
Serial Issue: 1
Title: Vanadio-oxy-dravite, NaV (sub 3) (Al (sub 4) Mg (sub 2) )(Si (sub 6) O (sub 18) )(BO (sub 3) ) (sub 3) (OH) (sub 3) O, a new mineral species of the tourmaline supergroup
Affiliation: Sapienza Universita di Roma, Dipartimento di Scienze della Terra, Rome, Italy
Pages: 218-224
Published: 201401
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 49
Accession Number: 2014-008054
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 9 tables
N51°40'00" - N51°40'00", E103°40'00" - E103°40'00"
Secondary Affiliation: Swedish Museum of Natural History, SWE, SwedenRussian Academy of Science, Institute of the Earth's Crust, RUS, Russian Federation
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Mineralogical Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201406
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