Pyrophanite

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Pyrophanite
General
Category Oxide mineral
Formula
(repeating unit)
MnTiO3
Strunz classification 4.CB.05
Dana classification 4.3.5.3
Crystal symmetry Trigonal rhombohedral
H-M symbol: (3)
Space group: R3
Unit cell a = 5.13948(7) Å, c = 14.2829(4) Å; Z=6
Identification
Color Deep blood-red to greenish black
Crystal habit Rarely as rosettes of hexagonal plates, typically granular, scaly; occurs as exsolution lamenae in franklinite and spinel
Crystal system Trigonal
Cleavage Perfect on {0221}
Fracture Conchoidal
Tenacity Brittle
Mohs scale hardness 5–6
Luster Submetallic
Streak Ochre yellow
Diaphaneity Subtranslucent to opaque
Specific gravity 4.537 measured
Optical properties Uniaxial (-)
Refractive index nω = 2.481 nε = 2.210
Birefringence δ = 0.271
References [1][2][3]

Pyrophanite is a manganese titanium oxide mineral with formula: MnTiO3. It is a member of the ilmenite group. It is a deep red to greenish black mineral which crystallizes in the trigonal system. It is a member of the ilmenite group.

Discovery and occurrence[edit]

It was first described in 1890 from an occurrence in the Harstigen Mine, Filipstad, Värmland, Sweden.[2] Its name was derived from the Greek πΰρ, fire, and φαίνεσθαι, to appear, because of the deep red color of the mineral.[2]

Its main occurrence is in manganese deposits that have undegone metamorphism. It also occurs in granite, amphibolite and serpentinite as an uncommon accessory mineral. Associated minerals include ilmenite, geikielite, hematite, spinel, gahnite, chromite, magnetite, ganophyllite, manganophyllite, hendricksite, garnet and calcite.[1]

References[edit]