põhimineraal

Põhimineraal is a term used in geology and mineralogy to describe a mineral that is considered a fundamental or primary component of a rock. This designation is often based on the mineral's abundance, its formation process, or its role in the rock's overall structure and chemical composition. In some contexts, põhimineraal refers to minerals that form directly from the melt during igneous rock crystallization, as opposed to secondary minerals that form later through alteration or weathering.

The concept of põhimineraal is particularly relevant when classifying igneous rocks. For example, in granite, feldspar and quartz are often considered põhimineraalid, while minerals like mica or amphibole might be referred to as accessory minerals if present in smaller quantities. In sedimentary rocks, põhimineraal might refer to the dominant clastic grains like quartz or feldspar that make up the bulk of the sediment, or it could refer to authigenic minerals that precipitate directly within the sediment pore spaces, such as calcite or clays, if they are a primary component of the rock formation. The specific definition can vary slightly depending on the geological context and the classification system being used, but the underlying idea is to identify the essential mineral constituents of a rock.