Orange Pickeringite from the Algares 30-Level Adit, Aljustrel Mine, Iberian Pyrite Belt, Portugal
| Autor: | Daniel de Oliveira, Fernanda Carvalho, João Pedro Veiga, Pedro Gonçalves, Igor Morais, Ugur D. Menda, Luís Albardeiro, João Xavier Matos, Teresa Pereira Silva |
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| Přispěvatelé: | DCM - Departamento de Ciência dos Materiais, CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N), DCR - Departamento de Conservação e Restauro |
| Rok vydání: | 2021 |
| Předmět: |
Stockwork
Iberian Pyrite Belt Underground mining (soft rock) Mineral halotrichite Geochemistry Geology Alotrichite Orange (colour) Mineralogy Geotechnical Engineering and Engineering Geology Hydrothermal circulation Halotrichite Algares mine Adit orange pickeringite Orange Pickeringite efflorescent minerals underground mining Efflorescent minerals Iberian Pyrite Belt sulphide ores QE351-399.2 Underground mining |
| Zdroj: | Repositório Científico de Acesso Aberto de Portugal Repositório Científico de Acesso Aberto de Portugal (RCAAP) instacron:RCAAP Minerals Volume 11 Issue 10 Minerals, Vol 11, Iss 1115, p 1115 (2021) |
| ISSN: | 2075-163X |
| Popis: | R 0052-GEO-FPI-5-E ALT20-03-0145-FEDER-000025 Project (PA 18111) The sheltered environment of the Algares +30 level adit (underground mine gallery) contributes to the preservation of secondary water-soluble minerals formed on the tunnel walls. The massive sulphide and related stockwork zone are hosted by the Mine Tuff volcanic unit and are exposed in the walls of the gallery, showing intense oxidation and hydrothermal alteration. Minerals from the halotrichite group were identified on the efflorescent salts, typically white fine-acicular crystals but also on aggregates with dark orange/brownish colour. Mineral characterization was performed using several methods and analytical techniques (XRD, XRF-WDS, SEM-EDS, DTA-TG), and the chemical formulas were calculated maintaining the ratio A:B∼= 1:2 in accordance with the general formula of the halotrichite group, AB2 (SO4 )4·22H2 O. This methodology allowed the assignment of the orange colour to the presence of trivalent iron on iron-rich pickeringite in partial substitution of aluminium. publishersversion published |
| Databáze: | OpenAIRE |
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