Sugilite

sugilite

armbrusterite

norrishite

namansilite

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Formula: KNa2Fe3+2(Li3Si12)O30
Cyclosilicate (ring silicate), osumilite group, lithium-bearing mineral
Specific gravity: 2.73 to 2.79
Hardness: 5½ to 6½
Streak: White
Colour: Pale pink, light brownish yellow, purple, colourless in transmitted light. Pink to purple colour due to the presence of Mn3+
Solubility:
Melting point: ~895oC
Common impurities: Ti,H2O
Environments

Plutonic igneous environments
Metamorphic environments

Sugilite occurs in stratabound metamorphosed manganese deposits and in peralkaline igneous rocks (Dana).

Localities

At Woods Mine, Darling county, New South Wales, Australia, sugilite is rare and occurs as small aggregates associated with serandite, namansilite, braunite, albite and manganese-rich amphibole (R&M 92.6.550-555).

At the Poudrette quarry, Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Quebec, Canada sugilite occurs in marble xenoliths associated with poudretteite, quartz, polylithionite and pectolite (Dana).

At the type locality, Iwagi Island, Inland Sea, Ehime Prefecture, Japan, sugilite occurs in aegirine syenite associated with albite, allanite, aegirine, andradite, apatite, pectolite, titanite and zircon (R&M 92.6.550-555).

At the Bruce mine, Sishen, Kathu, Gamagara, John Taolo Gaetsewe, Northern Cape, South Africa, sugilite has been found in a borehole core as blebs to about 1 mm associated with albite, armbrusterite, norrishite and serandite (R&M 92.6.550-555).

The Wessels Mine, Hotazel, Kalahari manganese field, Northern Cape, South Africa, is the source of the finest sugilite worldwide, both in massive form and crystallised. Associated minerals include wollastonite, pectolite, johannsenite, quartz, richterite, andradite and hydroxyapophyllite.
One sample has been found of sugilite with quartz, pectolite and strontianite (R&M 92.6.550-555).

At the N'Chwaning III Mine, N'Chwaning Mines, Kuruman, Kalahari manganese field, Northern Cape, South Africa, fibrous sugilite has been found associated with lipuite and taniajacoite on an oxidised manganese ore matrix (R&M 92.6.550-555).

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