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Basalt is distinguished from andesite by SiO 2 < 52%. Basalt is field B in the TAS classification. Vesicular basalt at Sunset Crater, Arizona. US quarter (24mm) for scale. Columnar basalt flows in Yellowstone National Park, US. Basalt is composed mostly of oxides of silicon, iron, magnesium, potassium, aluminum, titanium, and calcium.
Vesicular texture is a volcanic rock texture characterized by a rock being pitted with many cavities (known as vesicles) at its surface and inside. [ 1 ] This texture is common in aphanitic , or glassy, igneous rocks that have come to the surface of the Earth, a process known as extrusion .
The vesicular basalt is sample 15016, and it is sometimes called the seatbelt basalt. Back at Falcon , Scott and Irwin set about deploying the Apollo Lunar Surface Experiments Package (ALSEP). Scott would drill the holes for the heat-flow experiment and put in the probes, while Irwin would set up the rest of the equipment.
Basalt is a very common volcanic rock with low silica content. Rhyolite is a volcanic rock with high silica content. Rhyolite has silica content similar to that of granite while basalt is compositionally equal to gabbro. Intermediate volcanic rocks include andesite, dacite, trachyte, and latite. [citation needed]
Scoria is a pyroclastic, highly vesicular, dark-colored volcanic rock formed by ejection from a volcano as a molten blob and cooled in the air to form discrete grains called clasts. [ 1 ] [ 2 ] It is typically dark in color (brown, black or purplish-red), and basaltic or andesitic in composition.
The sample is a very vesicular basalt, rounded by surface erosion. Lithologically, it closely resembles samples 15535 and 15536, as well as a number of fragments in the rake samples from station 9A. [3] The seatbelt basalt is currently stored at the Lunar Sample Laboratory Facility at the Lyndon B. Johnson Space Center.
The vesicular and massive basalts occur in alternating bands, with the vesicular bands usually being the top and base of each flow. [ 10 ] [ 12 ] The basalt mineralogy consists of mainly of plagioclase , augite , magnetite , some ilmenite and volcanic glass .
A flood basalt (or plateau basalt [1]) is the result of a giant volcanic eruption or series of eruptions that covers large stretches of land or the ocean floor with basalt lava. Many flood basalts have been attributed to the onset of a hotspot reaching the surface of the Earth via a mantle plume . [ 2 ]