Orientite

sorosilicate

psilomelane

Formula: Ca8Mn3+10(SiO4)3(Si3O10)3(OH)10.4H2O
Sorosilicate (Si2O7 groups)
Specific gravity: 3.33
Hardness: 4½ to 5
Streak: Brown
Colour: Deep red to brown, maroon
Solubility: Soluble in hot hydrochloric acid; insoluble in nitric acid
Environments:

Sedimentary environments
Basaltic cavities

Orientite is of low temperature origin and forms in low alumina conditions, occurring with chalcedony variety jasper, psilomelane, manganite and baryte.

At Lake Manganese, Keweenaw county, Michigan, USA, orientite is associated with manganite, braunite, macfallite and pyrolusite all replacing calcite in fissures and lenses in basalt.

At the type locality in what was Oriente 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.

Common impurities: Al,Fe,V,Cu,Mg,K,H2O,S

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