Metabasalt, Proterozoic: two billion years old; Weyburn, Saskatchewan; Donated by Cugnet Farms, Geo-Pac Consulting and Drilling, Medora Resources Inc., Saskatchewan Geological Society, Saskatchewan Industry and Resources.
Basalt is a fine-grained volcanic rock formed when lava flowed on or near the surface and solidified. A metamorphic rock is one which has been changed from its original form by heat or pressure or both. Therefore, a metabasalt is a basalt, changed by heat, pressure or both and, additionally retains some of the characteristics of a basaltic rock. Metabasalt is a type of metamorphosed basalt from dykes that forms into amphibolite.