Types of Lava Rock
"Andesite porphyry" is the name used for these rocks with two crystal sizes. Andesite outcrop: Close view of an andesite lava flow at Brokeoff Volcano in California. Photo by the United States Geological Survey.
Basalt is a common extrusive igneous rock formed from the rapid cooling of basaltic lava exposed at or very near the surface of a planet or moon. Flood basalt describes the formation in a series of lava basalt flows.
Granite is a plutonic rock in which quartz makes up between 10 and 50 percent of the felsic components and alkali feldspar accounts for 65 to 90 percent of the total feldspar content. Applying this definition requires the mineral identification and quantification abilities of a competent geologist.
Igneous rocks are divided into two groups, intrusive or extrusive, depending upon where the molten rock solidifies. Intrusive Igneous Rocks: Intrusive, or plutonic, igneous rock forms when magma is trapped deep inside the Earth.
Lava rock, also known as igneous rock, is formed when volcanic lava or magma cools and solidifies. It is one of the three main rock types found on Earth, along with metamorphic and sedimentary. Typically, eruption occurs when there is an increase in temperature, a decrease in pressure or a change in composition.
Although lava rocks and mulch have some similar qualities, each is perfect for unique pieces of your landscape. Learn which is the best fit for your project.
Quartzite is a nonfoliated metamorphic rock composed almost entirely of quartz. It forms when a quartz-rich sandstone is altered by the heat, pressure, and chemical activity of metamorphism. These conditions recrystallize the sand grains and the silica cement that binds them together.
Rhyolite is an extrusive igneous rock formed during eruptions of granitic magma. Pumice, obsidian, and tuff are associated rock types.
The terms lava stone and lava rock are more used by marketers than geologists, who would likely say "volcanic rock" (since lava is a molten liquid and rock is solid). "Lava stone" may describe anything from a friable silicic pumice to solid mafic flow basalt, and is sometimes used to describe rocks that were never lava, but look as if they were (such as sedimentary limestone with dissolution pitting).
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