Creedite

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Creedite is a calcium aluminium sulfate fluoro hydroxide mineral with formula: Ca₃Al₂SO₄(F,OH)₁₀·2(H₂O). Creedite forms colorless to white to purple monoclinic prismatic crystals. It often occurs as acicular radiating sprays of fine prisms. It is translucent to transparent with indices of refraction of nα=1.461 nβ=1.478 nγ=1.485. It has a Mohs hardness of 3.5 to 4 and a specific gravity of 2.7.

Creedite was first described in 1916 from the Creed Quadrangle in Mineral County, Colorado. It is a product of intense oxidation of ore deposits.

References

• Mindat with localities
• Webmineral
• Mineral galleries