Greigite

Greigite is an iron sulfide mineral with formula:Fe(II)Fe(III)₂S₄. It is a magnetic sulfide analogue of the iron oxide magnetite. Greigite occurs as microscopic (< .03 mm) isometric hexoctahedral crystals and as minute sooty masses. It is a bio-mineral produced by and found in magnetotactic bacteria. It is a pale pink to metallic blue-black mineral with a specific gravity of 4.049 and a Mohs hardness of 4 to 4.5.

Additional recommended knowledge

Daily Sensitivity Test

Daily Visual Balance Check

Recognize and detect the effects of electrostatic charges on your balance

It was first described in 1964 and named for Penn State mineralogist and physical chemist Joseph W. Greig (1895-1977).

References

• Mineral Data PDF
• Mindat with location data
• Webmineral data