Images
Formula: Mn2+21Si8O27(OH)20
Inosilicate (chain silicate), manganese-bearing mineral
Crystal System: Monoclinic
Specific gravity: 3.46 to 3.584 measured, 3.599 calculated
Hardness: 3
Streak: White
Colour: Colourless to pink
Solubility: Decomposed by hydrochloric acid
Environments:
Metamorphic environments
Hydrothermal environments
Gageite is a rare manganese silicate.
Near Kuruman, South Africa, gageite is associated with leucophoenicite,
hausmannite, rhodochrosite and
manganoan calcite (HOM).
At the type locality, the Franklin Mine, Sussex county, New Jersey, USA, gageite is a late-stage, low to medium temperature mineral,
implanted on other species in fissures and solution cavities, in a metamorphosed
zinc-iron-manganese
deposit
(HOM, Webmin, Mindat, AM 53.309), associated with
zincite, willemite,
sclarite, pyrochroite,
leucophoenicite, calcite and
chlorophoenicite (HOM, Mindat).
Back to Minerals