Physical Properties
Chemical formula CaMgSi2O6
Class Inosilicate
Double chains of linked tetrahedra
Crystal system Monoclinic
Habit Prismatic
Finely disseminated
Color Light green
Hardness 5.5 to 6.5
Specific gravity 3.2 to 3.5
Cleavage Two perfect prismatic {1101}
Fracture Uneven
Luster Vitreous
Transparency Transparent to translucent
Streak White
Optical Properties
PPL Colorless if Fe-free
Non-pleochroic if Fe-free
Green if Fe
Brown if Fe
Pleochroic if Fe
XPL 3rd order colors
Prismatic or blocky grains
δ 0.030
Twinning Polysynthetic are common
Extinction Inclined
after Perkins, 327

Diopside in Hand Sample

Green diopside with red and white calcite

Diopside in Thin Section

Thin Section GigaPans

Diopside in plane polars
Diopside in crossed polars

Diopside, PPL

Diopside, XPL

Further Reading

Diopside at webmineral.com
Diopside at mindat.org