Does andesite have a Phaneritic texture?
Andesite is INTERMEDIATE in composition between MAFIC and FELSIC rocks. DIORITE – phaneritic rock (large crystals) of both mafic and felsic minerals. ANDESITE – aphanitic rock (small crystals) of both mafic and felsic minerals.
How do you identify andesite rocks?
Andesite is the name of a family of fine-grained, extrusive igneous rocks that are usually light to dark gray in color. They have a mineral composition that is intermediate between granite and basalt.
What is the texture of an igneous rocks?
The texture of an igneous rock made up entirely of crystals big enough to be easily seen with the naked eye is phaneritic. Phaneritic texture is sometimes referred to as coarse-grained igneous texture. Granite, the most well known example of an intrusive igneous rock, has a phaneritic texture.
What does andesite look like?
Andesite is a fine-grained, extrusive igneous or volcanic rock. It is dark grey and made up of equal amounts of light and dark minerals, although the crystals are too small to be seen without a magnifier. Occasionally andesite may contain some larger crystals. Or small round pockets that were gas bubbles.
What is the texture of andesite?
Andesite (/ˈændəzaɪt/) is an extrusive volcanic rock of intermediate composition. In a general sense, it is the intermediate type between basalt and rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predominantly of sodium-rich plagioclase plus pyroxene or hornblende.
Which rocks have a vesicular texture?
Rock types that display a vesicular texture include pumice and scoria.
How hard is andesite rock?
The hardness of andesite rocks on the Moh scale is 7.
What are rock textures?
In rock: Texture. The texture of a rock is the size, shape, and arrangement of the grains (for sedimentary rocks) or crystals (for igneous and metamorphic rocks). Also of importance are the rock’s extent of homogeneity (i.e., uniformity of composition throughout) and the degree of isotropy.
What are the 5 textures of igneous rocks?
Igneous textures are used by geologists in determining the mode of origin of igneous rocks and are used in rock classification. There are six main types of textures; phaneritic, aphanitic, porphyritic, glassy, pyroclastic and pegmatitic.
What is the use of andesite rock?
Andesite may be used as aggregate or fill, but it is not ideal for concrete applications because it is high in silica, and causes alkali-silica reactivity in the concrete. Andesitic volcanism is associated closely with porphyry copper deposits and it is a host rock for much of the world’s copper ore.
Is andesite a hard rock?
Andesite is an extrusive rock intermediate in composition between rhyolite and basalt. Andesite lava is of moderate viscosity and forms thick lava flows and domes. The word andesite is derived from the Andes Mountains in South America, where andesite is common. Andesite is the volcanic equivalent of diorite.
Andesite is the name used for a family of fine-grained, extrusive igneous rocks that are usually light to dark gray in color. They often weather to various shades of brown, and these specimens must be broken for proper examination. Andesite is rich in plagioclase feldspar minerals and may contain biotite, pyroxene,…
Is andesite an intrusive or extrusive igneous rock?
Andesite is an extrusive or intrusive igneous rock that is higher in silica than basalt and lower than rhyolite or felsite. (more below) Click the photo to see the full-size version. In general, color is a good clue to the silica content of lavas, with basalt being dark and felsite being light.
What is andesite composed of?
Andesite is a type of igneous rock that is formed by volcanic activity. It is usually dark grey or bown in colour. It usually exists as the solid form of volcanic lava or magma. The mineral composition of andesite includes biotite, pyroxene, or amphibole. It is known as a “host rock” for the popular gemstone, Andesine .
Are diorite and andesite similar?
Diorite and andesite are similar rocks. They have the same mineral composition and occur in the same geographic areas. The differences are in their grain sizes and their rates of cooling. Diorite crystallized slowly within the Earth. That slow cooling produced a coarse grain size.