What are basalt crystals composed of?

Not so much a crystal, as basalt is an igneous extrusive rock, but the basic mineralogy of basalt consists of the minerals pyroxene, plagioclase feldspar, and amphibole. Above is a garden-variety basalt. Olivine may also be present, and is very easy to spot in a hand sample: Look at that beaut! read more

Not so much a crystal, as basalt is an igneous extrusive rock, but the basic mineralogy of basalt consists of the minerals pyroxene, plagioclase feldspar, and amphibole. Above is a garden-variety basalt. read more

Basalt is a dark-colored, fine-grained, igneous rock composed mainly of plagioclase and pyroxene minerals. It most commonly forms as an extrusive rock, such as a lava flow, but can also form in small intrusive bodies, such as an igneous dike or a thin sill. It has a composition similar to gabbro. read more

Basalt is one of the most common rock types in the world. Basalt is the rock most typical of large igneous provinces. The largest occurrences of basalt are in the ocean floor that is almost completely made up by basalt. read more