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Tyuyamunite

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Tyuyamunite
General
CategoryVanadate mineral
Formula
(repeating unit)
Ca(UO2)2V2O8·(5–8)H2O
IMA symbolTyu[1]
Strunz classification4.HB.25
Dana classification40.2a.26.1
Crystal systemOrthorhombic
Crystal classDipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space groupPnna
Unit cella = 10.63 Å, b = 28.36 Å
c = 20.4 Å; Z = 4
Identification
ColourCanary yellow, lemon-yellow; greenish yellow (upon exposure to sunlight)
Crystal habitPlaty crystals often in radiating sprays, coatings, massive
CleavagePerfect on {001}, micaceous; distinct on {100} & {010}
Mohs scale hardness1+12 – 2
LustreAdamantine, waxy, pearly on {101}, dull
StreakYellow
DiaphaneityTranslucent to opaque
Specific gravity3.57 – 4.35
Optical propertiesBiaxial (−)
Refractive indexnα = 1.675 nβ = 1.860 – 1.870 nγ = 1.885 – 1.895
Birefringence0.210 – 0.220
Pleochroismweak: X = nearly colourless, Y = pale canary yellow, Z = canary yellow
2V angle30° to 45°
Dispersionnone
Other characteristics Radioactive
References[2][3][4][5]

Tyuyamunite (pronounced tuh-YOO-ya-moon-ite) is a very rare uranium mineral with formula Ca(UO2)2V2O8·(5–8)H2O. It is a member of the carnotite group. It is a bright, canary-yellow color because of its high uranium content. Also, because of tyuyamunite's high uranium content, it is radioactive.[6] It was named by Konstantin Avtonomovich Nenadkevich, in 1912, after its type locality, Tyuya-Muyun, Fergana Valley, Kyrgyzstan.[3]

Formation and transformation

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Tyuyamunite is formed by the weathering of uraninite, a uranium-bearing mineral. Tyuyamunite, being a hydrous mineral, contains water. Yet when it is exposed to the atmosphere it loses its water. This process changes tyuyamunite into a different mineral known as metatyuyamunite[6] Ca(UO2)2(VO4)2·3-5H2O.[7]

References

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  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ Handbook of Mineralogy
  3. ^ a b Tyuyamunite at Mindat
  4. ^ Tyuyamunite data on Webmineral
  5. ^ Tyuyamunite at Amethyst Galleries' Mineral Gallery
  6. ^ a b Lynch, Dan R. and Bob Lynch, "Tyuyamunite," Ed. Brett Ortler, Michigan Rocks & Minerals, Adventure Publications, 2010 ISBN 978-1591932390
  7. ^ Metatyuyamunite on Mindat
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