Mineral Information and Data:

Pigeonite
(Mg,Fe,Ca)SiO3 [CNMNC approved formula]

Named in 1900 after the locality: Pigeon Point, Minnesota, USA.

IMA status : Approved Species 1988 ()
CLASSIFICATION 
Dana
(8th edition) :
65.01.01.04  
  (65) Inosilicate Single-Width Unbranched Chains, W=1
  (65.01) with chains P=2
  (65.01.01) P2/c clinopyroxenes
  
Nickel-Strunz
(10th edition) :
09.DA.10
  (09) Silicates
  (09.D) Inosilicates* Structural terminology per Liebau (1985)
  (09.DA) with 2-periodic single chains, Si2O6; pyroxene family
  
Crystal system: Monoclinic System
Point group (H-M): 2/m — prismatic
Unit cell: a = 9.706, b = 8.95, c = 5.246, β = 108.59°
Crystal Habit: Crystals short prismatic, small grains
Twinning: Commonly twinned simply or multiply on {100} or {001}
  
Color: Brown, light purplish brown, greenish brown, black
Diaphaneity: Translucent to nearly opaque
Luster: Vitreous to dull
Hardness (Mohs): 6
Measured Density: 3.30 to 3.46 g/cm3
Cleavage: 4; {110} good, {001}, {010} and {100} parting
Tenacity: Brittle
Fracture: Uneven
Streak: Gray white
  
Geologic Setting: 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.
Mineral Association: Augite, olivine
  
Synonyms/varieties: Calc-clinobronzite, Calc-clinoenstatite, Calc-clinohypersthene

 

Pigeonite
Origin: Belmont Quarry, Loudon Co., Virginia, USA
Sample size: 0.7 x 1 cm
Photo: Diederik Visser

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