Class : Silicates
    Subclass : Sorosilicates
    Crystal system : Tetragonal
    Chemistry : Ca₂Al(AlSi)O₇
    Rarity : Quite common

Gehlenite is isomorphic with akermanite, with which it forms a continuous series and whose deposits it often shares. This calcium silicate is a mineral in carbonate rocks found in basic to ultra-basic volcanic rocks, limestones and dolomites transformed by thermal metamorphism, and certain calcic alkaline rocks and certain meteorites. Akermanite and gehlenite also crystallize in abundance in foundry and incinerator furnaces and are therefore essential constituents of metallurgical slag and bottom ash. It was named in honor of the German chemist Adolf Ferdinand Gehlen. Natural gehlenite occurs in short prismatic crystals with the appearance of pseudocubes modified by the octahedron, or in masses ; it is colorless to grayish, grayish green or brownish yellow to brown. Artificial crystals from foundries and incinerators have acicular to bacillary habits, very different from those of natural crystals.

Main photo : 20 cm gehlenite from Vata de Sus, Vata de Jos, Hunedoara County, Romania © Martins da Pedra

No twin known for this mineral species.

No fakes recorded for this mineral species.