Omphacite is a member of the clinopyroxene group of silicate minerals with formula: (Ca, Na)(Mg, Fe2+, Al)Si2O6.

The Mid-Ocean Ridge Basalt, which makes up oceanic crust, goes through ultrahigh-pressure metamorphic process and transforms to eclogite at depth ~60 km in the subduction zones.

[9] The major mineral components of eclogite include omphacite, garnet and high-pressure silica phases (coesite and stishovite).

Minerals such as glaucophane, lawsonite, titanite, and epidote occur with omphacite in blueschist facies metamorphic rocks.

[6] Due to the relatively small radius of (Na, Al) atoms, the unit cell volume linearly decreases as jadeite component increases.

When temperature reaches ~700–750 °C, the structure of omphacite becomes totally disordered and the space group will transform to C2/c.

[15] Although the atomic positions in the two space groups have a subtle difference, it does not clearly change the physical properties of omphacite.