Macphersonite | |
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General | |
Category | Carbonate mineral |
Formula (repeating unit) | Pb4(SO4)(CO3)2 (OH)2 |
IMA symbol | Mps[1] |
Strunz classification | 5.BF.40 |
Dana classification | 17.01.04.01 |
Crystal system | Orthorhombic |
Crystal class | Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) |
Space group | Pcab |
Unit cell | a = 10.37 Å, b = 23.10 Å, c = 9.25 Å, β = 106.43°; Z = 8 |
Identification | |
Formula mass | 1,078.90 g/mol |
Color | White, pale amber, colorless |
Crystal habit | Pseudo hexagonal, tabular |
Twinning | Polysynthetic, lamellar, contact |
Cleavage | Perfect on {010} |
Fracture | Uneven |
Mohs scale hardness | 2.5 - 3 |
Luster | Adamantine, otherwise resinous |
Streak | White |
Specific gravity | 6.50 |
Optical properties | Biaxial (-) |
Refractive index | nα = 1.870 nβ = 2.000 nγ = 2.010 |
Birefringence | δ = 0.140 |
2V angle | 35-36° |
Dispersion | r > v |
Ultraviolet fluorescence | A very strong and vivid yellow |
Other characteristics | Polymorph of leadhillite and susannite |
References | [2][3][4][5][6] |
Macphersonite, Pb4(SO4)(CO3)2 (OH)2, is a carbonate mineral that is trimorphous with leadhillite and susannite. Macphersonite is generally white, colorless, or a pale amber in color and has a white streak. It crystallizes in the orthorhombic system with a space group of Pcab. It is fairly soft mineral that has a high specific gravity.
Macphersonite is named after Harry Gordon Macpherson,[4] a keeper of minerals at the Royal Scottish Museum. It was discovered and accepted in 1984.