Greyish white crystals of the rare mineral ganomalite from Sweden: Jakobsberg Mine, Nordmark, Filipstad, Värmland County, Sweden. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY 4.0
Ganomalite
Ganomalite is an IMA-recognized mineral species in the silicate class, with the chemical formula Pb₉Ca₆(Si₂O₇)₄(SiO₄)O.
It crystallizes in the hexagonal crystal system (space group P-6). It is a member of the Ganomalite structural group.
Key properties: Mohs hardness 3; specific gravity 5.7; Resinous to vitreous luster; optically uniaxial.
IMA symbol Gnm, grandfathered status — known before the IMA’s founding, named in 1876.
Found in skarn assemblages (Jakobsberg, Sweden); in manganese ores in a metamorphosed stratiform zinc orebody (Franklin, New Jersey, USA).
It is found associated with Tephroite, lead, jacobsite, calcite, phlogopite, macedonite (Jakobsberg, Sweden); clinohedrite, willemite, andradite, franklinite (Franklin, New Jersey, USA).
Its name comes from the Greek for luster, in allusion to its appearance.