savikivet

Savikivet is a Finnish term used in geology to describe a fine‑grained, clay‑rich sedimentary rock that splits readily along bedding planes. The name derives from savi, meaning clay, and kivi, meaning stone. In English-language geology, rocks with similar characteristics are often called claystone, mudstone, or shale, but Finnish usage sometimes distinguishes savikivet from other fissile rocks based on texture and mineralogy.

Formation and characteristics

Savikivet forms through the lithification of clay‑ and silt‑sized particles deposited in low‑energy environments such as lakes, floodplains, or shallow seas. The resulting rock is typically very fine grained and may show a laminar or platy texture that facilitates easy breaking along layers. The mineral composition is dominated by clay minerals, with variable amounts of quartz or feldspar. Weathered surfaces can appear earthy, and the rock’s color ranges from grey to brown or greenish tones, depending on oxidation and mineral content.

Occurrence and significance

In Finland, savikivet appears in several sedimentary sequences across different Paleozoic and Mesozoic rocks and can serve as a stratigraphic marker in field mapping and borehole correlations. Because of their low strength and fissility, they influence geotechnical considerations for construction projects, foundations, and tunneling, where careful assessment of stability and drainage is required.

See also

Shale, claystone, mudstone, argillite.