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Category Vanadate mineral
(repeating unit)
Strunz classification 4.HB.25
Dana classification 40.2a.26.1
Crystal system Orthorhombic
Crystal class Dipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space group Pnna
Unit cell a = 10.63 Å, b = 28.36 Å
c = 20.4 Å; Z = 4
Colour Canary yellow, lemon-yellow; greenish yellow (upon exposure to sunlight)
Crystal habit Platy crystals often in radiating sprays, coatings, massive
Cleavage Perfect on {001}, micaceous; distinct on {100} & {010}
Mohs scale hardness 1½ - 2
Lustre Adamantine, waxy, pearly on {101}, dull
Streak Yellow
Diaphaneity Translucent to opaque
Specific gravity 3.57 - 4.35
Optical properties Biaxial (-)
Refractive index nα = 1.675 nβ = 1.860 - 1.870 nγ = 1.885 - 1.895
Birefringence 0.210 - 0.220
Pleochroism weak: X = nearly colourless, Y = pale canary yellow, Z = canary yellow
2V angle 30° to 45°
Dispersion none
Other characteristics Radioactive.svg Radioactive
References [1][2][3][4]

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.[5] It was named by Konstantin Avtonomovich Nenadkevich, in 1912, after its type locality, Tyuya-Muyun, Fergana Valley, Kyrgyzstan.[2]

Formation and transformation[edit]

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[5] Ca(UO2)2(VO4)2·3-5H2O[6]


  1. ^ Handbook of Mineralogy
  2. ^ a b Tyuyamunite at Mindat
  3. ^ Tyuyamunite data on Webmineral
  4. ^ Tyuyamunite at Amethyst Galleries' Mineral Gallery
  5. ^ a b Lynch, Dan R. and Bob Lynch, "Tyuyamunite," Ed. Brett Ortler, Michigan Rocks & Minerals, Adventure Publications, 2010 ISBN 978-1591932390
  6. ^ Metatyuyamunite on Mindat

External links[edit]