Olmiite Locality: N'Chwaning II Mine, N'Chwaning Mines, Kuruman , Kalahari manganese fields, Northern Cape Province , South Africa ( Locality at mindat.org ) Size: 4.1 x 3.0 x 2.4 cm. Rich beige olmiite in crystallized spherical aggregates, from finds 4-5 years ago. Ex. Charlie Key Collection. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Olmiite
A rare calcium-manganese silicate named for Italian mineralogist Filippo Olmi, approved in 2006.
Intro adapted from Wikipedia (CC BY-SA).
Olmiite is an IMA-recognized mineral species in the silicate class, with the chemical formula CaMn[SiO₃(OH)](OH).
It crystallizes in the orthorhombic crystal system (space group Pbca).
Key properties: Mohs hardness 5–5.5; specific gravity 3.05; White streak; Vitreous luster; optically biaxial.
IMA symbol Olm, IMA status: approved, named in 2006.
A product of hydrothermal alteration of primary sedimentary and low-grade metamorphic manganese ores.
It is found associated with Poldervaartite, celestine, sturmanite, bultfonteinite, hematite.
The mineral was named to honor Filippo Olmi (1959-2005), for his mineralogical studies at the CNR-Istituto di Geoscienze e Georisorse in Florence, Italy.