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Hematite | Blog myjewels.ru

Formula Fe2O3
Molecular mass 159.69 g/mol
admixture
IMA Status Valid
Systematics according to IMA (Mills et al., 2009)
Class Oxides and hydroxides
Group corundum
Physical properties
Color Reddish brown to iron black
Dash color Red-brown
Shine Metallic, brushed
Transparency Transparent in thin sheets
Mohs hardness 5.5—6.5
fragility Fragile
Cleavage Missing
kink semi-conchoidal
Density 4.9—5.3 g/cm³
Crystallographic properties
space group R3c (R3 2/c)
Syngony Trigonal
Twinning
Optical properties
optical type uniaxial
Refractive index nα = 3.150–3.220, nβ = 2.870–2.940
Birefringence 0.28
dichroism
optical relief Short
Dispersion of optical axes Missing
Pleochroism Weak
Luminescence Missing
Diffusion

Varieties of hematite

Many of the various forms of hematite have separate names. The steel-gray crystals and coarse-grained varieties have a lustrous metallic sheen and are known as mirror iron ore; thin scaly types are called micaceous hematite. Much hematite occurs in a soft, fine-grained, earthy form called red ocher. Intermediate between these types are compact varieties, often with a kidney-like surface (bud ore) or a fibrous structure (pencil ore). Red ocher is used as a coloring pigment; used for polishing sheet glass.


Strode Anna

Anna Strod – director of the jewelry online store Myjewels.ru Author and editor of the jewelry blog Myjewels.ru

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