GOLDMANITE

    Class : Silicates
    Subclass : Nesosilicates
    Crystal system : Cubic
    Chemistry : Ca3V2(SiO4)3
    Rarity : Very rare

Goldmanite is a very rare calcic garnet, usually dark green in color. It is a vanadium garnet belonging to the ougrandite series which forms a continuous solid solution with the grossular. Like most ougrandites, goldmanite is found in regional metamorphic and contact rocks of impure limestones, but also in magnetite skarns and vanadium sedimentary rocks. It was named in honor of Marcus Isaac Goldman, a specialist in sedimentary petrology at the US Geological Survey. Like all garnets, goldmanite occurs in isometric crystals, generally small dodecahedra.

Main photo : Goldmanite from Rybnícek, Pezinok, Slovakia © Lubos Hrdlovic

Goldmanite in the World

The largest known goldmanite crystals measure 3 mm and come from the Russian deposit of Tashelginskiye (Siberia). Crystals of 2 mm are also reported in the Czech Republic at Tetetice (Saint Runadlo) near Klatovy as well as in Rybnícek near Pezinok (Slovakia).

Goldmanite in France

In France, goldmanite is known in the small skarn of Coat-an-Noz (Côtes d'Armor).

Twinning

No twins known for this mineral species.

Fakes and treatments

No fakes recorded for this mineral species.


Hardness : 6 to 7
Density : 3.74 to 3.77
Fracture : Conchoidal
Streak : White

TP : Translucent to transparent
RI : 1.821
Birefringence : 0
Optical character : None
Pleochroism : None
Fluorescence : None

Solubility : Hydrofluoric acid

Magnetism : NoneRadioactivity : None