Emmonsite

Formula:   Fe₂Te₃O₉ ^. 2H₂O

Origin of name:   For S. Emmons, American geologist

Crystal system:   Triclinic

Crystal class:   -1

Twinning:

Unit cell: a = 7.90 Ǻ, b = 8.00 Ǻ, c = 7.62 Ǻ, α = 96.7°, β = 95°, γ = 84.5°

Colour:  Yellow-green

Diaphaneity:

Luster:   Vitreous to dull

Habit:   Crystals acicular, minute in small groups; compact microcrystalline masses; fibrous crusts; scaly coatings

Hardness:   ~ 5

Specific gravity:   4.52 to 4.53

Cleavage:   3; {010} perfect and two directions at 85° and 95° to the {010}

Tenacity: 

Streak: 

Synonyms/varieties:

Comments: