Ferrimolybdite | |
---|---|
General | |
Category | Molybdate mineral |
Formula (repeating unit) | Fe3+2(MoO4)3·8(H2O) or Fe3+2(MoO4)3·n(H2O) |
IMA symbol | Fmyb[1] |
Strunz classification | 7.GB.30 |
Crystal system | Orthorhombic |
Crystal class | Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) |
Space group | Pmmn |
Unit cell | a = 6.665, b = 15.423 c = 29.901 [Å]; Z = 8 |
Identification | |
Color | Canary-yellow, straw-yellow, greenish yellow |
Crystal habit | Acicular tufted to radial aggregates; powdery, earthy |
Cleavage | Distinct on {001} |
Fracture | Uneven |
Mohs scale hardness | 1-2 |
Luster | Adamantine, silky, earthy |
Streak | Light yellow |
Diaphaneity | Transparent to translucent |
Specific gravity | 2.99 |
Optical properties | Biaxial (+) |
Refractive index | nα = 1.720 - 1.810 nβ = 1.730 - 1.830 nγ = 1.850 - 2.040 |
Birefringence | δ = 0.130 - 0.230 |
Pleochroism | X = Y = clear to nearly colorless; Z = dirty gray to canary-yellow |
2V angle | 26° to 32° (calculated) |
References | [2][3][4] |
Ferrimolybdite is a hydrous iron molybdate mineral with formula: Fe3+2(MoO4)3·8(H2O)[3] or Fe3+2(MoO4)3·n(H2O).[2] It forms coatings and radial aggregates of soft yellow needles which crystallize in the orthorhombic system.