Ludlockite

Formula:  PbFe₄As₁₀O₂₂

Origin of name:  For F. Ludlow Smith and C. Locke Key, American collectors

Crystal system:  Triclinic

Crystal class:  -1

Twinning:  Common on {0-11}, lamellar

Unit cell: a = 10.41 Å, b = 11.95 Å, c = 9.86 Å, α = 113.9°, β = 99.7°, γ = 82.7°

Colour:  Red

Diaphaneity: 

Luster:  Subadamantine

Habit:  Crystals elongated, flattened, lamellar

Hardness:  1.5 to 2

Specific gravity:  4.40

Cleavage:  2; {0-11} micaceous, {0kl} cleavages yield frayed crystals

Tenacity:  Sectile and flexible

Streak:  Light brown

Synonyms/varieties:

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