General Information:
Chemical Formula:
Fe++SO4·7(H2O)
Composition:
(Molecular Weight = 278.02 gm)
Iron 20.09 % Fe
Hydrogen 5.08 % H
Sulfur 11.53 % S
Oxygen 63.30 % O
Empirical Formula:
Fe2+(SO4)·7(H2O)
Name Origin:
From the Greek melas, "black."
Physical Properties:
Cleavage:
[001] Perfect, [110] Distinct
Color:
green, yellow green, brownish black, bluish green, or greenish white.
Density:
1.89 - 1.9, Average = 1.89
Diaphaniety:
Subtransparent to translucent
Habits:
Efflorescences - Crystals covering matrix, generally produced from transpiro-evaporation., Encrustations - Forms crust-like aggregates on matrix., Capillary - Very slender and long, l ike a thread or hair (e.g. millerite).
Hardness:
2 - Gypsum
Luminescence:
None.
Luster:
Vitreous (Glassy)
Streak:
white
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