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Silicate

Oxy-foitite

(Fe²⁺Al₂)Al₆(Si₆O₁₈)(BO₃)₃(OH)₃O
Hardness7
Crystal systemHexagonal
ClassSilicate
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Oxy-foitite

Oxy-foitite is an IMA-recognized mineral species in the silicate class, with the chemical formula (Fe²⁺Al₂)Al₆(Si₆O₁₈)(BO₃)₃(OH)₃O.

It crystallizes in the hexagonal crystal system (space group R3m). It is a member of the Tourmaline structural group.

Key properties: Mohs hardness 7; specific gravity 3.143; Gray streak; Vitreous luster; optically uniaxial.

IMA symbol Ofoi, IMA status: approved, named in 2016.

From granitic pegmatite in high-grade migmatitic gneisses of pelitic composition. The oxy-foitite formation is related to the partial melting of these gneisses.

It is found associated with Muscovite, K-feldspar, quartz.

The mineral was named to honor Franklin F. Foit Jr. (b. 1942), Washington State University, Pullman, Washington, USA, for his work on the tourmaline-supergroup.

Index entry. This entry combines official IMA/RRUFF species data with published physical-property data — a full written entry hasn’t been published yet. Browse more O minerals or help write this entry.