Aldermanite

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Formula: Mg₅Al₁₂(PO₄)₈(OH)₂₂.32H₂O
Hydrated phosphate containing hydroxyl
Crystal System: Monoclinic
Specific gravity: 2.1 (calculated)
Hardness: 2
Streak: White
Colour: Colourless in transmitted light
Luminescence: Not fluorescent under UV
Solubility: Soluble in mineral acids
Environments

Sedimentary environments

At the type Locality, the Moculta Phosphate Quarry, Angaston, Mount Lofty Ranges, South Australia, aldermanite is a secondary mineral in cavities in a brecciated metamorphosed sedimentary phosphate deposit, formed by the alteration of fluellite (HOM, Mindat, AM 66.1099). Associated minerals include limonite, fluellite, apatite, beraunite, cacoxenite, childrenite, crandallite, cyrilovite, dufrénite, gorceixite, leucophosphite, minyulite, rockbridgeite, variscite and wavellite (Dana, Mindat). Aldermanite is one of the last phosphate minerals to form, and is occasionally replaced by crandallite (AJM 17.1.11).

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