Galaxite
Mn2+Al2O4 [CNMNC approved formula]
Named for Galax, Virginia, USA, close to Bald Knob, North Carolina, and for the plant, galax, after which the town is named.
| IMA status : | Valid species (Pre-IMA 1932) Grandfathered |
| CLASSIFICATION | |
| Dana (8th edition) : |
07.02.01.02 |
| (07) Multiple Oxides | |
| (07.02) (A+ B++)2 X4 Spinel group | |
| (07.02.01) (Aluminum subgroup) | |
| Nickel-Strunz (10th edition) : |
04.BB.05 |
| (04) Oxides and Hydroxides | |
| (04.B) Metal:Oxygen = 3:4 and similar | |
| (04.BB) With only medium-sized cations | |
| Crystal system: | Cubic System |
| Point group (H-M): | m3m (or 4/m 3 2/m) — hexoctahedral |
| Space group: | Fd3m |
| Unit cell: | a = 8.258Å, Z =8 |
| Crystal Habit: | As octahedra and rounded grains, to 0.5 mm; as exsolution blebs. |
| Twinning: | On {111} as both twin and composition plane, the spinel law, probable. |
| Color: | Black, red-brown, red to yellow; in transmitted light, golden yellow, brownish orange, mahogany-red, deep red to reddish black |
| Diaphaneity: | Opaque; may be translucent in thin section. |
| Luster: | Vitreous |
| Hardness (Mohs): | 7.5 |
| Measured Density: | 4.234 g/cm3 |
| Fracture: | Conchoidal |
| Streak: | Red-brown |
| Geologic Setting: | In carbonate-rich, silica-undersaturated parts of metamorphosed manganese deposits. |
| Mineral Association: | Alleghanyite, rhodonite, sonolite, spessartine, tephroite, kutnohorite, manganhumite, jacobsite, kellyite, alabandite (Bald Knob, North Carolina, USA); katoptrite, magnetite, manganostibite, magnussonite, tephroite, manganhumite, manganosite (Brattfors mine, Sweden) |
Black granular galaxite with reddish alleghanyite and white kutnohorite.Origin: Bald Knob, Alleghany County, North Carolina, USA.
Photo: Jeff Weissman