Common in rapidly cooled siliceous volcanic rocks. Inverted varieties with exsolved augite are found in layered mafic intrusives. From metamorphosed iron formations.
IMA Status:
Valid Species (Pre-IMA) 1900
Locality:
Pigeon Point, Cook Co., Minnesota Link to MinDat.org Location Data.
CI meas= -0.039 (Good) - where the CI = (1-KPDmeas/KC) CI calc= -0.039 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2104,KPDmeas= 0.2104,KC= 0.2025 Ncalc = 1.67 - 1.7
Optical Data:
Biaxial (+), a=1.683-1.722, b=1.684-1.722, g=1.704-1.752, bire=0.0210-0.0300, 2V(Calc)=0-26, 2V(Meas)=0-32. Dispersion weak to distinct, r < v.
Pleochroism (x):
colorless, faint pink, pink, or pale greenish brown.
Pleochroism (y):
colorless, faint pink, brownish pink, or pale greenish brown.
Pleochroism (z):
colorless, faint green, pale green, or pale reddish brown.
Calculated Properties of Pigeonite
Electron Density:
Bulk Density (Electron Density)=3.34 gm/cc note: Specific Gravity of Pigeonite =3.38 gm/cc.
Fermion Index:
Fermion Index = 0.03 Boson Index = 0.97
Photoelectric:
PEPigeonite = 5.66 barns/electron U=PEPigeonite x rElectron Density= 18.89 barns/cc.
Radioactivity:
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Pigeonite is Not Radioactive
Chemical Formula: 
