Orange Pickeringite from the Algares 30-Level Adit, Aljustrel Mine, Iberian Pyrite Belt, Portugal
نویسندگان
چکیده
The sheltered environment of the Algares +30 level adit (underground mine gallery) contributes to preservation secondary water-soluble minerals formed on tunnel walls. massive sulphide and related stockwork zone are hosted by Mine Tuff volcanic unit exposed in walls gallery, showing intense oxidation hydrothermal alteration. Minerals from halotrichite group were identified efflorescent salts, typically white fine-acicular crystals but also aggregates with dark orange/brownish colour. Mineral characterization was performed using several methods analytical techniques (XRD, XRF-WDS, SEM-EDS, DTA-TG), chemical formulas calculated maintaining ratio A:B ? 1:2 accordance general formula group, AB2(SO4)4·22H2O. This methodology allowed assignment orange colour presence trivalent iron iron-rich pickeringite partial substitution aluminium.
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ژورنال
عنوان ژورنال: Minerals
سال: 2021
ISSN: ['2075-163X']
DOI: https://doi.org/10.3390/min11101115