Gabbro, a type of intrusive igneous rock, is formed when magma cools and solidifies inside the crust of the Earth. Because it cools slowly, it is coarsely grained.Know More
Gabbro is the intrusive equivalent to basalt, an extrusive rock formed by molten magma that cools on the Earth's surface. However, unlike extrusive rocks, which cool rapidly when exposed to the atmosphere, intrusive rocks, surrounded by pre-existing rock, push up from within the Earth and cool in a process that can take millions of years. Large deposits of gabbro lie beneath the oceanic crust, where magma cools extremely slowly to form large-grained holocrystalline masses. Gabbro is found in many places on Earth. It is also present on the moon.
The German geologist Christian Leopold von Buch, who studied the volcanic origins of minerals in Italy, named gabbro after a town in Tuscany. Gabbro is dense and dark-colored. Unlike granite, it contains no quartz and little silica. It contains pyroxene, plagioclase, amphibole and olivine. It often contains large but low-grade amounts of gold, silver, platinum, chromium, nickel and cobalt. Its dark appearance precludes its widespread use in construction, but it is often used for paving stones, headstones for graves and kitchen countertops, in which case it is referred to erroneously as "black granite."Learn more about Geology
There are a couple of theories regarding how natural gas may have been formed in the Earth. One theory stipulates that natural gas was formed when prehistoric animals and plants were buried under deep layers of Earth. Another theory states that the Earth's natural gas was created even earlier, when the Earth was first formed more than 4.5 billion years ago.Full Answer >
Archipelagos form when underwater volcanoes continually produce molten magma that cools and builds up to eventually form a group of islands. Although archipelagos can form by erosion or by the movement or evaporation of water, volcanic activity is the most common cause of archipelago formation.Full Answer >
Granite makes up a portion of the Earth's crust, and exists in virtually all land areas around the world. Granite forms the middle layer of the Earth's core, along with several other minerals and rocks. It forms the basis of the continental crust, and it also exists in seabeds.Full Answer >
Magma rises to the Earth's surface due to a combination of differences in density with other rocks in the crust and pressure. The differences in density cause it to move upward until its density is the same as the other rocks in the crust. It then builds pressure, causing it to rise to the surface.Full Answer >