Järnkarbonatmineral

Järnkarbonatmineral are a group of minerals that contain iron and carbonate as their primary chemical components. These minerals are characterized by the presence of the carbonate anion (CO3^2-) and iron cations (Fe^2+ or Fe^3+). The most common and well-known iron carbonate mineral is siderite, which has the chemical formula FeCO3. Siderite is a relatively soft mineral and typically appears in shades of brown, yellow, or gray. It is often found in sedimentary rocks, particularly in shales and sandstones, and can also occur in hydrothermal veins.

Other less common iron carbonate minerals exist, often with complex compositions that include additional elements. For example, ankerite is a calcium-magnesium-iron carbonate with the general formula (Ca,Mg,Fe)CO3, where iron content can vary. Dolomite, while primarily a calcium-magnesium carbonate, can also contain significant amounts of iron, leading to a compositional range that borders on iron carbonate minerals.

The formation of iron carbonate minerals is often associated with reducing conditions, where dissolved iron is available and can react with carbonate ions. They can form through precipitation from groundwater, diagenetic processes in sedimentary environments, or from hydrothermal fluids. Due to their iron content, some iron carbonate minerals can be a source of iron, though their economic significance as ore minerals is generally limited compared to iron oxides. Their presence can also be an indicator of specific geological conditions.