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Pigeonite [abbr. Pgt ]

Year of discovery: 1900 (Pigeon Point, USA), 1933 (Japan)

Locality list: 106 localities of pigeonite

• (Mg,Fe,Ca)(Mg,Fe)Si₂O₆
• [(Mg²⁺,Fe²⁺,Ca²⁺)][(Mg²⁺,Fe²⁺)][(SiO₃)₂]^4-
• Ca/(Mg+Fe+Ca)=0.05-0.2

• Class: Ca-Mg-Fe pyroxene group < Pyroxene supergroup
• Class: Inosilicate (Single chain)
• Variety: Ferropigeonite (+Fe-rich)

• Ca/(Mg+Fe+Ca) > 0.2: Augite
• Ca/(Mg+Fe+Ca) < 0.05, Mg > Fe: Clinoenstatite, Enstatite, Akimotoite
• Ca/(Mg+Fe+Ca) < 0.05, Fe > Mg: Clinoferrosilite, Ferrosilite

• Si => Ti: Geikielite

• Color: Black, Brown, Greenish brown
• Streak: Gray
• Luster: Vitreous
• Diaphaneity: Translucent

• Habit: Short prismatic

• Cleavage: Perfect on {110} (2 planes, 90 degree)
• Hardness: 6
• Density: 3.4

• System: Monoclinic
• Group: 2/m, P2₁/c
• Lattice: a=9.7, b=9.0, c=5.2, β=108.6

Synonym: Calc-clinobronzite, Calc-clinoenstatite, Calc-clinohypersthene