Åkermanite (Ca2Mg[Si2O7]) is a melilite mineral of the sorosilicate group, containing calcium, magnesium, silicon, and oxygen.

It is a product of contact metamorphism of siliceous limestones and dolomites, and rocks of sanidinite facies.

Sanidinite facies represent the highest conditions of temperature of contact metamorphism and are characterized by the absence of hydrous minerals.

[4][3] Åkermanite ranks a 5 or 6 on the Mohs scale of mineral hardness, and can be found gray, green, brown, or colorless.

It was "grandfathered" in as a species of mineral because it was described prior to 1959, before the founding of the International Mineralogical Association.