Gayite

gayite

morinite

natrodufrenite

fluorapatite

Images

Formula: NaMnFe₅(PO₄)₄(OH)₆.2H₂O
Valence: NaMn²⁺Fe³⁺₅(PO₄)₄(OH)₆.2H₂O
Hydrated phosphate, dufrénite group, manganese- and ferric iron- bearing mineral
Crystal system: Monoclinic
Specific gravity: 3.15 measured, 3.245 calculated
Hardness: 4 to 5
Streak: Olive-green
Colour: Greenish black
Luminescence: No fluorescence under UV
Solubility: Dissolves slowly in dilute hydrochloric acid
Environments

Pegmatites

Localities

At the type locality, the Gigante pegmatite, Candelaria District, Cruz del Eje department, Córdoba Province, Argentina, gayite occurs associated with morinite, natrodufrénite and quartz in cavities in massive fluorapatite, as clusters of tabular, striated crystals up to 130 µm on edge. The mineral is greenish black with an olive green streak and vitreous lustre. Thin tablets are transparent. Gayite is brittle, with one perfect cleavage and irregular fracture (AM 95.2.386-391).
Gayite from the Gigante pegmatite - Image

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