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Formula: Ca8Mn3+10(SiO4)3(Si3O10)3(OH)10.4H2O
Sorosilicate (Si2O7 groups),
manganese-bearing mineral
Crystal System: Orthorhombic
Specific gravity: 3.05 to 3.33 measured, 3.48 calculated
Hardness: 4½ to 5
Streak: Brown
Colour: Deep red to brown, maroon
Solubility: Soluble in hot hydrochloric acid; insoluble in nitric acid
Common impurities: Al,Fe,V,Cu,Mg,K,H2O,S
Environments:
Sedimentary environments
Basaltic cavities
Orientite is of low temperature origin and forms in low alumina conditions, occurring with
jasper,
psilomelane,
manganite and baryte
(Dana).
Localities
At the type locality, the Firmeza District, Santiago de Cuba Province, Cuba, orientite
occurs in manganese ore bodies in
trachyte-like rocks and
andesite
tuff, agglomerates and
limestone, associated with
todorokite,
manganite,
pyrolusite
neotocite, ferruginous
chalcedony,
baryte, low quartz,
calcite, analcime,
stilbite, chabazite and
laumontite
(HOM).
Orientite from the Firmeza District -
Image
At the Manganese Mine, Copper Harbor, Grant Township, Keweenaw County, Michigan, USA, orientite is associated
with manganite, braunite,
macfallite and pyrolusite all
replacing calcite
in fissures and lenses in basalt
(Dana, HOM, R&M 89.6.508).
Orientite from Keweenaw County - Image
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