Dating volcanic rock
Minerals such as alkali feldspar, leucite, nepheline, sodalite, phlogopite mica, and apatite may be present in the groundmass.
Basalt has high liquidus and solidus temperatures—values at the Earth's surface are near or above 1200 °C (liquidus) and near or below 1000 °C (solidus); these values are higher than those of other common igneous rocks.
Although usually characterized as "dark", basaltic rocks exhibit a wide range of shading due to regional geochemical processes.
Due to weathering or high concentrations of plagioclase, some basalts can be quite light-coloured, superficially resembling andesite to untrained eyes.
and has also formed on the Moon, Mars, Venus, and the asteroid Vesta.
The crustal portions of oceanic tectonic plates are composed predominantly of basalt, produced from upwelling mantle below, the ocean ridges.
Basalt is usually grey to black in colour, but rapidly weathers to brown or rust-red due to oxidation of its mafic (iron-rich) minerals into hematite and other iron oxides and hydroxides.In particular, the relative abundance of europium compared to the other REE is often markedly higher or lower, and called the europium anomaly.