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Basalt is an extrusive igneous rock, sometimes porphyritic, and is often both fine-grained and dense. Basalt in the tops of subaerial lava flows and cinders will often be highly vesiculated, imparting a lightweight "frothy" texture to the rock. The term basalt is often casually applied to shallow intrusive rocks with a composition typical of basalt, but rocks of this composition with a phaneritic groundmass should generally be referred to as gabbro. The crustal portions of oceanic tectonic plates are predominantly made of basalt. Unweathered basalt is frequently black to greenish-black in color, characterized by a preponderance of calcic plagioclase feldspars and pyroxene together with minor amounts of accessory minerals such as olivine. Basaltic cinders are often red. Glass may be present, particularly as rinds on rapidly chilled surfaces of lava flows, and is commonly (but not exclusively) associated with underwater eruptions. Amygdaloidal structure is common in relic vesicles and beautifully crystallized species of zeolites, quartz or calcite are frequently found.
The lavaLava is molten rock that a volcano expels during an eruption. Due to its high temperature, lava can be quite fluid when first exuded from a volcanic vent, but eventually solidifies into rock. However, the lava may flow many miles before solidification. flows of the Deccan TrapsThe Deccan Traps is located in west-central India and is one of the largest volcanic features on Earth. It consists of multiple layers of solidified basalt that together are more than 2,000 m thick and covers an area of 500,000 km². The Deccan Traps forme in IndiaThe Republic of India is a large multicultural country in South Asia, with a population of over one billion. The Indian economy is the fourth largest in the world, in terms of purchasing power parity, and is the world's second-fastest growing economy., the Columbia River PlateauThe Columbia River Plateau lies across parts of the states of Washington, Oregon, and Idaho. During late Miocene and early Pliocene times, one of the largest basaltic lava floods ever to appear on the earth's surface engulfed about 63,000 square miles (16 of WashingtonWashington is a state in the Pacific Northwest of the United States. It should not be confused with Washington, DC, the nation's capital. To avoid confusion, the state is often called Washington state . Although the state capital is Olympia, the largest c and OregonOregon is a state located in the western United States bordering the Pacific Ocean, California, Washington, Idaho, and Nevada. Its northern border lies along the Columbia River and the east along the Snake River. Two north-south mountain ranges the Coasta states in the United StatesThe United States of America also referred to as the United States U. America ¹ or the States is a federal republic in central North America, stretching from the Atlantic in the east to the Pacific Ocean in the west. It shares land borders with Canada in, as well as the TriassicThe Triassic is a Geologic period that extends from about 248 to 202 million years (My or 'megayears') before the present. The extinction event that closed the Triassic period has recently been more accurately dated, but as with most older geologic period lavas of eastern North America are basalts. Perhaps the most famous basalt flow in the world is the Giant's Causeway on the northern coast of Ireland, in which the vertical joints form hexagonal columns and give the impression of having been artificially constructed. The dark areas visible on Earth's moon, the lunar mares, are plains of basalt, and basalt Moon samples were brought to Earth by the astronauts of the Apollo program. Pliny used the word basalt and it is said to have had an Ethiopian origin, meaning a black stone.
See also: List of minerals
Volcanology
Igneous rocks
