Drysdallite

Formula:   Mo(Se,S)2

Origin of name:   For A.R.  Drysdall, Zambia, Director Geological Survey of Zambia

 

Crystal system:   Hexagonal

Crystal class:   6/m 2/m 2/m

Twinning:

Unit cell: a = 3.287 Å, c = 12.925 Å

 

Colour:   Grayish black with a brownish tint

Diaphaneity:  Opaque

Luster:   Metallic

Habit:   Granular massive, steep pyramidal crystals to 0.5 mm in other minerals

Hardness: 2

Specific gravity:   6.25

Cleavage:   1; {0001} perfect

Tenacity: Pliable, difficult to pulverise

Streak:   Brownish black

 

Synonyms/varieties:

 

Comments: Found in the oxidation zone of a uranium deposit in a talc schist in assocation with uraninite, apatite, masuyite and secondary uranium minerals

 

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