Mineralpedia Details for Robertsite

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Robertsite

Formula: Ca₂Mn³⁺₃O₂(PO₄)₃·3H₂O
Crystal System: Monoclinic
Crystal Habit: Aggregates, Felted
Cleavage: Good, None, None
Luster: Adamantine
Color: blood red, brownish black, dark red, reddish brown, black
Streak: brown
Class: Monoclinic - Prismatic
Hardness: 3.5
WebMineral: View Robertsite
Mindat: View Robertsite

Robertsite from Hagendorf-Süd, Oberpfälzer Wald, Bavaria, Germany

Deep internal red Robertsite as radial plates with concentrically zoned Rockbridgeite-Frondelite.

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Robertsite from Tip Top mine, Custer Co., South Dakota, United States

Special Info: Type Locality, XRD Confirmed, EDS Confirmed

Long, deep red bladed Robertsite (XRD) possibly phasing into Mitridatite. Robertsite will usually be found as stubby little deep red crystals at the Tip Top. On this specimen, the Robertsite forms plates to 2mm. There is some late-stage apatite probably a product of weathering. Quartz matrix with layers of lavender carbonate apatite.