Lunar Basalt

Basalt

Basalt ; buh-SALT) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron exposed at or very near the surface of a rocky planet or moon. More than 90% of all volcanic rock on Earth is basalt. Rapid-cooling, fine-grained basalt has the same chemical composition and mineralogy as slow-cooling, coarse-grained gabbro. The eruption of basalt lava is observed by geologists at about 20 volcanoes per year. Basalt is also an important rock type on other planetary bodies in the Solar System. For example, the bulk of the plains of Venus, which cover ~80% of the surface, are basaltic; the lunar maria are plains of flood-basaltic lava flows; and basalt is a common rock on the surface of Mars.

lunar

Adjective

1. Of, pertaining to, or resembling the Moon (that is, Luna, the Earth's moon).
2. Shaped like a crescent moon; lunate.

Noun

1. The middle bone of the proximal series of the carpus in the wrist, which is shaped like a half-moon.
2. An observation of a lunar distance (“the angle between the Moon and another celestial body”), especially for establishing the longitude of a ship at sea.

basalt

Noun

1. A hard mafic igneous rock of varied mineral content; volcanic in origin, which makes up much of the Earth's oceanic crust.
2. A type of unglazed pottery.