Specific gravity: 3.43
Streak: Brown with reddish tint
Colour: Brown to reddish brown, maroon
Common impurities: Ti,Al,Fe,Cr,V,Cu,Mg,K,Na,H2O
At Manganese lake, Keweenaw county, Michigan, USA, macfallite occurs in
basalt associated with
orientite and pyrolusite. The
assemblage replaces calcite in fissures and lenses in the
(Dana, HOM, AM 65.406),
and most of the crystals are coated with late-stage calcite.
Macfallite also occurs with pumpellyite, and these two mineral appear to
have formed at the same time
At Faggiona, Italy, macfallite replaces braunite under low-temperature metamorphic conditions associated with braunite, quartz and manganoan richterite (HOM).
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