Steinefni

Steinefni is the Icelandic term for minerals, the solid, naturally occurring inorganic substances that form the crystalline components of rocks. A mineral possesses a definite chemical composition and a characteristic crystal structure, which together distinguish it from rocks and organic materials. Minerals occur individually as crystals or as part of a larger rock matrix and can be identified by physical properties such as hardness, luster, color, cleavage, and habit.

Most steinefni are silicate minerals, but the category also includes carbonates, oxides, sulfides, sulfates, halides, and native elements. Common rock-forming minerals include quartz, feldspar, micas, and calcite; important ore minerals include galena (lead sulfide), sphalerite (zinc sulfide), and magnetite (iron oxide); native elements such as copper and gold occur in metallic form. Minerals form through geological processes such as crystallization from silicate melts, metamorphic recrystallization, precipitation from hydrothermal fluids, and diagenetic growth in sediments.

They are distributed throughout Earth's crust in rocks, soils, and sediments, with their abundance and variety reflecting geological history and tectonic setting. Humans rely on minerals as sources of metals, industrial materials, and specialty compounds, while scientists study them to understand planetary formation, crystallography, and the evolution of Earth's crust. Modern techniques for studying steinefni include optical microscopy, X-ray diffraction, and electron microscopy.

See also: mineral, mineralogy, crystal structure, Mohs scale, ore.