Wyllieite

wyllieite

trolleite

scorzalite

graftonite

Images

Formula:
Formerly the formula was given as
(Na,Ca,Mn2+,☐)2Mn2+2Al(PO4)3
but now the IMA gives it as
NaNaMn(Fe2+Al(PO4)3
Anhydrous normal phosphate, wyllieite group, manganese-bearing mineral, forms a series with rosemaryite and with ferrowyllieite
Crystal System: Monoclinic
Specific gravity: 3.61 calculated
Hardness: 4 to 4½
Streak: Dirty olive-green
Colour: Deep bluish green to deep oily green, grey-green to greenish-black
Environments

Pegmatites

Wyllieite occurs in zoned complex granite pegmatites (HOM).

Localities

At the Buranga pegmatite, Muhororo, Ngororero District, Western Province, Rwanda, wyllieite is associated with trolleite and scorzalite (HOM).

At the type locality, the Old Mike mine, Custer, Custer Mining District, Custer county, South Dakota, USA, wyllieite occurs as masses and crude crystals up to 10 cm in size, in zoned, complex granite pegmatites. Associated minerals include quartz, muscovite, plagioclase, graftonite and sarcopside, also arrojadite-(KFe), arsenopyrite, scorzalite, ludlamite, vivianite and garnet (Mindat,Dana).

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