Kivilaji

Kivilaji is a term used in geology, particularly in Finnish-language literature, that denotes a rock type. It refers to the classification of rocks based on their origin and mineral composition, and is a fundamental concept in field studies, mapping, and resource assessment. While the term is generic, it is commonly used to group rocks within the broader rock cycle.

Rocks are traditionally divided into igneous, sedimentary, and metamorphic kivilajit. Igneous rocks form from the cooling and solidification of molten material, with felsic and mafic varieties such as granite and basalt illustrating chemical diversity. Sedimentary rocks arise from the accumulation and lithification of sediments, including sandstone, limestone, and shale, reflecting past environments. Metamorphic rocks result from the transformation of existing rocks under heat and pressure, producing forms like slate, schist, marble, and gneiss.

Determining the kivilaji of a sample involves field observations of texture and mineral content, as well as laboratory techniques such as petrographic microscopy and geochemical analysis. The classification aids interpretation of geological histories, guides exploration for minerals and water, and supports construction-related assessments of rock suitability.

Notes: In Finnish geology, kivilaji is often discussed alongside mineral terminology and depositional environments, and serves as a practical umbrella term for describing rocks by their genesis and composition.