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Johannsenite (Photo) [abbr. Jhn ]

Year of discovery: 1932 (Temperino mine, Italy, Monte Civillina, Italy, and Franklin mine, USA), 1960 (Japan)

Locality list: 32 localities of johannsenite

• CaMnSi₂O₆
• [Ca²⁺][Mn²⁺][(SiO₃)₂]^4-

• Class: Pyroxene supergroup
• Class: Inosilicate (Single chain)

• Polymorph: Bustamite (High temperature, Triclinic)

• Ca => Mg: Kanoite, Donpeacorite
• Ca => Na: Namansilite

• Mn => Mg: Diopside (Series)
• Mn => Fe: Hedenbergite (Series)
• Mn => Zn: Petedunnite

• Color: Bluish green, Grayish white
• Tarnish: Brown
• Streak: White
• Luster: Vitreous
• Diaphaneity: Translucent

• Habit: Acicular, Prismatic
• Aggregate: Radial

• Cleavage: Distinct on {110} (2 planes, 90 degree)
• Hardness: 6
• Density: 3.6

• System: Monoclinic
• Group: 2/m, C2/c
• Lattice: a=9.9, b=9.0, c=5.3, β=105.5

Synonym: Ferro-johannsenite