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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 .
Flaked stone artefacts from Australia, made of tachylite. A second mode of occurrence of tachylite is in the form of lava flows.Basaltic rocks often contain a small amount of glassy ground-mass, and in the limburgites this becomes more important and conspicuous, but vitreous types are far less common in these than in the acid lavas.
Basalt (UK: / ˈ b æ s ɒ l t,-ɔː l t,-əl t /; [1] [2] US: / b ə ˈ s ɔː l t, ˈ b eɪ s ɔː l t /) [3] is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon.
When extrusive rocks make contact with the atmosphere they cool quickly, so the minerals do not have time to form large crystals. The individual crystals in an aphanitic igneous rock are not distinguishable to the naked eye. Examples of aphanitic igneous rock include basalt, andesite, and rhyolite.
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]
Its striking colours and water-holding properties can make it attractive for landscaping and drainage works. [8] Scoria can be used for high-temperature insulation, as in gas barbecue grills. [9] The ancient Romans used cinders as construction aggregates, one of the earliest industrial uses of volcanic rocks. [7]
The basement rock of the Marsili Basin is vesicular basalt. [6] Due to the abundance (10–30% of rock volume) and size (up to 3 or 4 mm) of the vesicles, it is likely that the basalt was emplaced as a flow rather than a sill. Overlaying the basement is 250 meters of calcareous mud and ooze with interbedded volcanoclastic layers.
Amygdules in lava from Kaiserstuhl in Germany. Amygdules or amygdales (/ ə ˈ m ɪ ɡ dj uː l z,-d eɪ l z /) form when the vesicles (pores from gas bubbles in lava) of a volcanic rock or other extrusive igneous rock are infilled with a secondary mineral, such as calcite, quartz, chlorite, or one of the zeolites. [1]