Pigeonit from Loundoun Co., Virginia, USA — Photo: Slashme · CC BY 4.0
Pigeonite
A calcium-poor clinopyroxene bridging augite and the orthopyroxenes — common in volcanic rocks.
Intro adapted from Wikipedia (CC BY-SA).
Pigeonite is an IMA-recognized mineral species in the silicate class, with the chemical formula (Mg,Fe,Ca)₂Si₂O₆.
It crystallizes in the monoclinic crystal system (space group P2_1/c). It is a member of the Pyroxene structural group.
Key properties: Mohs hardness 6; specific gravity 3.17–3.46; typically brown or green or black; white streak; [Vitreous.] luster; refractive index 1.711; optically biaxial.
IMA symbol Pgt, IMA status: approved, named in 1900.
Common in rapidly cooled siliceous volcanic rocks. Inverted varieties with exsolved augite are found in layered mafic intrusives. From metamorphosed iron formations. Also in meteorites.
It is found associated with Augite, olivine.
The name refers to the occurrence at Pigeon Point, Minnesota, USA.
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