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| Pyrophanite | |
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| Category: | Oxide mineral |
| Formula: | MnTiO3 |
| Imasymbol: | Pph[1] |
| Strunz: | 4.CB.05 |
| Dana: | 4.3.5.3 |
| System: | Trigonal |
| Class: | Rhombohedral (same H-M symbol) |
| Symmetry: | R |
| Unit Cell: | a = 5.13948(7) Å, c = 14.2829(4) Å; Z = 6 |
| Color: | Deep blood-red to greenish black |
| Habit: | Rarely as rosettes of hexagonal plates, typically granular, scaly; occurs as exsolution lamenae in franklinite and spinel |
| Cleavage: | Perfect on |
| Fracture: | Conchoidal |
| Tenacity: | Brittle |
| Mohs: | 5–6 |
| Luster: | Submetallic |
| Streak: | Ochre yellow |
| Diaphaneity: | Subtranslucent to opaque |
| Gravity: | 4.537 measured |
| Opticalprop: | Uniaxial (-) |
| Refractive: | nω = 2.481 nε = 2.210 |
| Birefringence: | δ = 0.271 |
| Impurities: | Fe, Zn |
| References: | [2] [3] [4] |
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 was first described in 1890 from an occurrence in the Harstigen Mine, Filipstad, Värmland, Sweden.[3] Its name was derived from the Greek πΰρ, fire, and φαίνεσθαι, to appear, because of the deep red color of the mineral.[3]
Its main occurrence is in manganese deposits that have undergone 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.[2]