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A lithophysa (plural lithophysae, from Greek lithos "stone" + physan "to blow") [1] is a felsic volcanic rock with a spherulitic structure and interior cavity with concentric chambers. Its outer shape is spherical or lenticular.
Volcanic rocks (often shortened to volcanics in scientific contexts) are rocks formed from lava erupted from a volcano. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and metamorphic rocks and constitute an important element of some sediments and sedimentary rocks. For these ...
Also called Indianite. A mineral from the lime-rich end of the plagioclase group of minerals. Anorthites are usually silicates of calcium and aluminium occurring in some basic igneous rocks, typically those produced by the contact metamorphism of impure calcareous sediments. anticline An arched fold in which the layers usually dip away from the fold axis. Contrast syncline. aphanic Having the ...
A vug, vugh, or vugg (/ v ʌ ɡ /) [1] is a small- to medium-sized [quantify] cavity inside rock. It may be formed through a variety of processes. It may be formed through a variety of processes. Most commonly, cracks and fissures opened by tectonic activity ( folding and faulting ) are partially filled by quartz , calcite , and other secondary ...
Two independent teams of scientists identified volcanic rock fragments that are approximately 2.8 billion years old. One fragment, however, is even older, dating back to about 4.2 billion years.
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. As magma rises to the surface the pressure on it decreases ...
In the 1900s, deep drilling brought up warm water and volcanic rock. He said the top of it sits about 4,000 feet underground. It probably last erupted toward the end of the Cretaceous period which ...
Trachybasalt – Volcanic rock – A volcanic rock with a composition between basalt and trachyte Hawaiite – Volcanic rock – a sodic type of trachybasalt, typically formed by ocean island volcanism; Trachyte – Extrusive igneous rock – A silica-undersaturated volcanic rock; essentially a feldspathoid-bearing rhyolite