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Omphacite (Photo) [abbr. Omp ]

Year of discovery: 1815 (Weißenstein, Germany), 1922 (Japan)

Locality list: 44 localities of omphacite

• (Ca,Na)(Mg,Al)Si₂O₆
• (Ca,Na)(Mg,Al,Fe)Si₂O₆
• [(Ca²⁺,Na⁺)][(Mg²⁺,Al³⁺)][(SiO₃)₂]^4-
• CaMgFe/(CaMgFe+NaAlFe)=0.2-0.8

• Class: Ca-Na pyroxene group < Pyroxene supergroup
• Class: Inosilicate (Single chain)

• CaMgFe/(CaMgFe+NaAlFe) < 0.2: Jadeite
• CaMgFe/(CaMgFe+NaAlFe) > 0.8: Enstatite, Ferrosilite, Wollastonite

• Mg => Fe: Aegirine-augite (Series)

• Color: Dark green
• Streak: Pale green
• Luster: Vitreous
• Diaphaneity: Translucent

• Habit: Acicular, Prismatic

• Cleavage: Perfect on {110} (2 planes, 90 degree)
• Hardness: 5-6
• Density: 3.3

• System: Monoclinic
• Group: 2/m, P2₁/n
• Lattice: a=9.7, b=8.8, c=5.2, β=106.6

Synonym: Diopsidejadeite, Mayaite