Braggite
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Braggite is a sulfide mineral of platinum, palladium and nickel with chemical formula: (Pt, Pd, Ni)S. It is a dense (specific gravity of 10), steel grey, opaque mineral which crystallizes in the tetragonal crystal system.[3] It is the central member in the platinum group end-members cooperite and vysotskite.
Braggite | |
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General | |
Category | Sulfide mineral |
Formula (repeating unit) | (Pt,Pd,Ni)S |
IMA symbol | Bg[1] |
Strunz classification | 2.CC.35a |
Dana classification | 2.8.5.3 |
Crystal system | Tetragonal |
Crystal class | Dipyramidal (4/m) H-M symbol: (4/m) |
Space group | P42/m |
Unit cell | a = 6.367 Å, c = 6.561 Å; Z = 8 |
Identification | |
Color | Steel grey; white in reflected light |
Crystal habit | Prismatic crystals and rounded grains |
Twinning | Rarely observed |
Cleavage | None |
Mohs scale hardness | 1.5 |
Luster | Metallic |
Diaphaneity | opaque |
Specific gravity | 10 (measured) 9.383 (calculated) |
Optical properties | Anisotropism distinct in polished section |
References | [2][3][4][5] |
It was first described in 1932 for an occurrence in the Bushveld Igneous Complex of South Africa. Its name came from William Henry Bragg (1862–1942) and his son, William Lawrence Bragg (1890–1971). It was the first mineral that was discovered with the assistance of X rays.[4][5]
It occurs as magmatic segregations in layered igneous intrusions such as Bushveld, the Stillwater igneous complex, the Lac des Îles igneous complex, the island of Rùm intrusive, the Great Dyke and many others.[4][5] It is one of the most common platinum group minerals.