Bobfergusonite
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Bobfergusonite is a mineral with formula Na2Mn5FeAl(PO4)6. The mineral varies in color from green-brown to red-brown. It was discovered in 1986 in Manitoba, Canada, and named for Robert Bury Ferguson (born 1920). As of 2012[update], the mineral has only been found in Canada and Argentina.
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Bobfergusonite | |
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General | |
Category | Phosphate mineral |
Formula (repeating unit) | Na2Mn5FeAl(PO4)6 |
IMA symbol | Bfg[1] |
Strunz classification | 8.AC.15 |
Dana classification | 38.2.4.5 |
Crystal system | Monoclinic |
Crystal class | Prismatic (2/m) (same H-M symbol) |
Space group | P21/n[2] |
Unit cell | a = 12.773 Å, b = 12.486 Å, c = 11.038 Å; β = 114.35(13)°; Z = 4 |
Identification | |
Color | Green-brown to red-brown |
Cleavage | Perfect on {010} Parting on {100}[3] |
Fracture | Irregular/Uneven |
Tenacity | Brittle |
Mohs scale hardness | 4 |
Luster | Sub-vitreous, resinous, greasy |
Streak | Yellow-brown |
Diaphaneity | Translucent[4] to transparent[3] |
Density | 3.54 g/cm3 |
Optical properties | Biaxial (+) |
Refractive index | nα = 1.694(1) nβ = 1.698(1) nγ = 1.715(2) |
Birefringence | δ = 0.021 |
Pleochroism | Visible: X=Y= yellow-orange Z= orange |
2V angle | 46° |
Dispersion | Relatively strong |
Ultraviolet fluorescence | Not fluorescent |
References | [4] |
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