Galaxite , Jacobsite , Wiserite Dimensions: 11.6 cm x 7.3 cm x 2.0 cm Locality: Kaso Mine, Kanuma City, Tochigi Prefecture, Kanto Region, Honshu Island, Japan An incredibly rare specimen of the Spinel Group species galaxite from the Kaso Mine in Japan. In addition to the rare galaxite, both jacobsite and wiserite are present. This piece is a polished specimen which shows brown-red galaxite with semi-metallic black-grey jacobsite and minor tan wiserite. It is accompanied by a classic label from Josef Vajdák/Pequa Rare Minerals. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Galaxite
Manganese aluminate — 'mangan-spinel' — an isometric spinel occasionally used as a collector's gemstone.
Intro adapted from Wikipedia (CC BY-SA).
Galaxite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Mn²⁺Al₂O₄.
It crystallizes in the cubic crystal system (space group Fd3m). It is a member of the Spinel structural group.
Key properties: Mohs hardness 7.5; specific gravity 4.234; Red-brown streak; Vitreous luster.
IMA symbol Glx, grandfathered status — known before the IMA’s founding, named in 1932.
Found in carbonate-rich, silica-undersaturated parts of metamorphosed manganese deposits.
It is found associated with Alleghanyite, rhodonite, sonolite, spessartine, tephroite, kutnohorite, manganhumite, jacobsite, kellyite, alabandite (Bald Knob, North Carolina, USA).
The name refers to Galax, Virginia, USA, close to Bald Knob, North Carolina, and for the plant, galax, after which the town is named.