General Information:
Chemical Formula:KFe+++4(AsO4)3(OH)4·6-7(H2O)
Composition:(Molecular Weight = 705.84 gm)Potassium 5.54 %
K Iron 7.91 %
FeArsenic 31.84 %
AsHydrogen 2.57 %
H Oxygen 52.13 %
O Empirical Formula: KFe3+(AsO4)3(OH)4·7(H2O)
Name Origin:From the Greek, farmakon for "poison" and sideros for "iron."
Physical Properties: Cleavage:[100] Indistinct
Color:olive green, emerald green, reddish brown, yellowish brown, or honey yellow.
Density:2.8 - 3, Average = 2.9
Diaphaniety:Subtransparent to subtranslucent
Habits:Blocky - Crystal shape tends to be equant (e.g. feldspars)., Crystalline - Coarse - Occurs as well-formed coarse sized crystals., Earthy - Dull, clay-like texture with no visible crys talline affinities, (e.g. howlite).
Hardness:2.5 - Finger Nail
Luminescence:None.
Luster:Adamantine - Resinous
Streak:yellowish green
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