Mineral
Siderita
FeCO₃ · Carbonatos
Siderite is an iron carbonate common in hydrothermal settings that crystallises in rhombohedra, with colour controlled by impurities and the oxidation state.
In hydrothermal veins it shows habits ranging from well-defined rhombohedral crystals to laminar aggregates, crusts and more massive coatings. Its colour is typically brown, ochre or golden. It is intensified by surface alteration of iron. It can also be influenced by inclusions of haematite.
It commonly occurs with quartz, sulphides and fluorite. At Panasqueira it forms part of the classic gangue assemblage that accompanies tungsten mineralisation. It is common in these hydrothermal systems.
Etymology
From the Greek 'sideros' (iron).
Specimens in the collection (6)
- Siderita — Socavón Santa Bárbara, El Arteal, Cuevas del Almanzora, Almería, Andalucía, España № 0480
- Siderita — Túnel del Arteal, Cuevas del Almanzora, Almería, Andalucía, España № 0481
- Siderita — La Unión, Murcia, España № 0553
- Siderita — Minas da Panasqueira, Aldeia de S. Francisco, Covilhã, Castelo Branco, Portugal № 0554
- Siderita — Mina Quien Tal Pensara (Mina Rica), Pulpí, Almería, Andalucía, España № 0555
- Siderita — Mina La Gitana, Sopuerta, Vizcaya, España № 0596