Diabaasikivi

Diabaasikivi, also known as diabase or dolerite, is a common mafic, holocrystalline, subvolcanic rock. It is characterized by its fine to medium-grained texture, which typically exhibits an ophitic or subophitic texture where lath-shaped plagioclase crystals are enclosed by pyroxene. Diabaasikivi forms when molten magma intrudes into pre-existing rock formations and cools relatively quickly below the Earth's surface, but not so quickly that it becomes a volcanic glass.

Geologically, diabaasikivi is often found in dikes, sills, and laccoliths, indicating its intrusive origin. It is a common rock type found in many parts of the world, often associated with ancient volcanic areas or rift zones. Its mineral composition is primarily composed of calcic plagioclase feldspar and pyroxene, typically augite. Olivine may also be present in some varieties.

In terms of its physical properties, diabaasikivi is generally a dark-colored rock, ranging from dark gray to black. It is known for its durability and resistance to weathering, making it a valuable material for construction purposes. Historically, it has been used as a building stone, for paving, and in the production of crushed stone for road construction and concrete aggregate. Its fine grain size and toughness contribute to its suitability for these applications.