Johannite

Formula:  Cu(UO2)2(SO4)2(OH)2 . 8H2O

Origin of name:   For Johann Sebastian, Archduke of Austria

 

Crystal system:  Triclinic

Crystal class:  1

Twinning:  Common on {010} about [001] axis, simpler or lamellar

Unit cell: a = 16.54 Ǻ, b = 18.02 Ǻ, c = 6.84 Ǻ, α = 90.9°, β = 90.63°, γ = 110.6°

 

Colour:  Emerald-green to greenish yellow

Diaphaneity: 

Luster:  Vitreous

Habit:  Crystals thick tabular, elongated on c-axis, or prismatic; drusy, subparallel, or spheroidal aggregates; coatings

Hardness:  2 to 2.5

Specific gravity:  3.32

Cleavage:  1; {100} good

Tenacity: 

Streak:  Pale green

 

Synonyms/varieties:

 

Comments: 

 

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