Mineral Information and Data:

Anthoinite
AlWO3(OH)3 [CNMNC approved formula]

Named for Raymond Anthoine (1888-1971), Belgian mining engineer, who wrote on prospecting of alluvial deposits.

IMA status : Valid species (Pre-IMA 1947) Grandfathered
CLASSIFICATION 
Dana
(8th edition) :
48.03.03.01  
  (48) Anhydrous Molybdates and Tungstates
  (48.03) (Basic Anhydrous)
  (48.03.03)
  
Nickel-Strunz
(10th edition) :
07.GB.35
  (07) Sulfates (selenates, tellurates, chromates, molybdates, wolframates)
  (07.G) Molybdates, Wolframates and Niobates
  (07.GB) With additional anions and/or H2O
  
Crystal system: Triclinic System
Point group (H-M): 1 — pinacoidal
Unit cell: a = 8.196(1) Å, b = 9.187(1) Å, c = 11.316(1) Å α = 92.82(1)°, β = 94.08(1)°, γ = 90.23(1)°
Crystal Habit: Crystals tabular, microscopic; chalk-like masses, pseudomorphs after scheelite
  
Color: White (when free of iron)
Diaphaneity: Translucent
Luster: Earthy, dull
Hardness (Mohs): 1
Measured Density: 4.8 g/cm3
Cleavage: 1; {001} perfect
Streak: White
  
Geologic Setting: In placers with cassiterite and wolframite and in quartz veins with ferberite, which appears to replace it (Mt. Misobo mine, Congo); in altered skarn (Kara mine, Tasmania).
Mineral Association: Ferberite, scheelite (Mt. Misobo mine, Congo); mpororoite, scheelite (Kara mine, Tasmania); raspite, ferberite, ferritungstite (Gifurwe mines, Rwanda): ferberite, scheelite, ferritungstite, russellite, mpororoite (Kalzas Mountain, Canada)
  

 

Anthoinite
White platy anthoinite with brown ferritungstite
Origin: Nyakabingu, Bumbogo, Rwanda
Sample size: 1 x 1.5 cm
Photo: Diederik Visser

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