Ianthinite

ianthinite

schoepite

uraninite

dewindtite

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Formula: U⁴⁺₂(UO₂)₄O₆(OH)₄.9H₂O
Oxide, uranyl mineral
Crystal System: Orthorhombic
Specific gravity: 5.16 measured, 5.00 calculated
Hardness: 2 to 3
Streak: Brown, violet
Colour: Violet-black, dark violet in transmitted light
RADIOACTIVE
Environments

Sedimentary environments

Ianthinite is a rare secondary mineral in the unoxidised portions of sedimentary uranium deposits. Associated minerals include uraninite, schoepite, becquerelite, kasolite, parsonsite, dewindtite and fourmarierite (HOM).

Localities

The type locality is the Shinkolobwe mine, Shinkolobwe, Kambove District, Haut-Katanga, DR Congo.
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Alteration

Ianthinite is stable only in a somewhat reducing environment, because it contains U⁴⁺ which will continue to oxidise under normal atmospheric conditions. It is purple-black when fresh; on exposure to air it gradually turns brown and eventually alters completely to yellow schoepite (Lauf2).

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