Ferrobobfergusonite

ferrobobfergusonite

fillowite

arrojadite

ferrowyllieite

Image from (CM 59.3.617–627)

Formula: ☐Na₂Fe²⁺₅Fe³⁺Al(PO₄)₆
Phosphate
Crystal System: Monoclinic
Specific gravity: 3.68 measured and 3.69 calculated
Hardness: About 5
Streak: Pale green-yellow
Colour: Deep green-brown
Environments

Pegmatites

Ferrobobfergusonite is a relatively new mineral, approved in 2017.

Localities

At the type locality, the Victory Mine, Custer, Custer Mining District, Custer county, South Dakota, USA, ferrobobfergusonite has been found associated with ferrowyllieite, schorl, fillowite, arrojadite, quartz and muscovite. Broken pieces of massive ferrobobfergusonite are blocky or tabular with single crystals up to 0.9 × 0.7 × 0.4 mm (CM 59.3.617–627).

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