What is the luster of gabbro?
Gabbro can be polished to a brilliant black luster. Brightly polished gabbro is used to make cemetery markers, kitchen counter tops, floor tiles, facing stone, and other dimension stone products. It is a highly desirable rock that stands up to weathering and wear.
What is gabbro used for?
Gabbro is widely used as crushed stone for concrete aggregate, road base material, and railroad ballast. Smaller quantities are cut and polished for dimension stone and called black granite.
What is an example of gabbro?
Examples of gabbro. In the foliated gabbro, andesine also predominates, but with minor oligoclase. These coarse-grained patches are igneous in origin and grade into finer-grained gabbro at the edges. The gabbro also contains apatite, pyrrhotite and zircon as accessory minerals.
What is Phaneritic and Aphanitic?
APHANITIC TEXTURE – Igneous rocks that form on the earth’s surface have very fine-grained texture because the crystals are too small to see without magnification. PHANERITIC TEXTURE – Igneous rocks with large, visible crystals because the rock formed slowly in an underground magma chamber.
What is the Lustre of granite?
The plagioclase feldspars are generally white with a porcelaneous luster. The K-feldspars are generally the ones that give granite its color variations from yellow to orange to pink or blue. Dark K-feldspars can give granite its black varieties as well.
Is dacite mafic or felsic?
Dacite is a felsic extrusive rock, intermediate in composition between andesite and rhyolite. It is often found associated with andesite, and forms lava flows, dikes, and, in some cases, massive intrusions in the centres of old volcanoes.
Where is gabbro commonly found?
mid-ocean ridges
Gabbro is a dense, mafic intrusive rock. It generally occurs as batholiths and laccoliths and is often found along mid-ocean ridges or in ancient mountains composed of compressed and uplifted oceanic crust.
Are granite and gabbro similar?
Granite is a coarse-grained igneous rock with average grain size ranging from 1 to 25 millimeters. Gabbro is generally coarse grained, with crystals in the size range of 1 mm or greater.
Where can I find gabbro?
Gabbro is a dense, mafic intrusive rock. It generally occurs as batholiths and laccoliths and is often found along mid-ocean ridges or in ancient mountains composed of compressed and uplifted oceanic crust.
What is the aphanitic equivalent of gabbro?
Basalt
Basalt is the aphanitic (fine-textured) extrusive equivalent of gabbro. From the Latin word “pumex”, meaning “pumice”. A vesicular, glassy volcanic rock, generally of rhyolite composition (felsic). Often light in color.