What is special about andesite?
Andesite is a gray to black volcanic rock with between about 52 and 63 weight percent silica (SiO2). Andesites contain crystals composed primarily of plagioclase feldspar and one or more of the minerals pyroxene (clinopyroxene and orthopyroxene) and lesser amounts of hornblende.
Where is andesite most commonly found?
Not only the Andes, where the name was first applied to a series of lavas, but most of the cordillera (parallel mountain chains) of Central and North America consist largely of andesites. The same rock type occurs in abundance in volcanoes along practically the entire margin of the Pacific Basin.
Is andesite hard or soft?
The hardness of andesite rocks on the Moh scale is 7.
How did andesite form?
Andesite is a volcanic rock. It is fine-grained because it forms by the rapid cooling of magmas usually when it erupts onto the Earth’s surface and forms lava flows. Andesite forms from magma that contains less quartz (silica) than rhyolite but more than basalt.
What is the importance of andesite rock?
It is fairly strong, which allows it to be used in road and railway construction, and as fill gravel. The grayish colored rocks seen between railway ties are often andesite or its close relative, basalt. Perhaps the most interesting use of andesite is as proof of volcanic activity on Mars.
What is andesite rock used for?
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.
What are andesite rocks used for?
Is andesite plutonic or volcanic?
Main types of igneous rocks
| Weight % of SiO2 | Plutonic rock type | Volcanic rock equivalent |
|---|---|---|
| 45-53 | Gabbro | Basalt |
| 53-63 | Diorite | Andesite |
| 63-68 | Granodiorite | Dacite |
| 68-75 | Granite | Rhyolite |
How strong is andesite?
Andesite
| Renewable | Yes |
|---|---|
| Tool | |
| Blast resistance | 6 |
| Hardness | 1.5 |
| Luminant | No |
Where is andesite rock found?
Andesite is a rock typically found in volcanoes above convergent plate boundaries between continental and oceanic plates.
Is andesite volcanic or plutonic?
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.
Is andesite an intrusive igneous rock?
Intrusive igneous rocks crystallize below Earth’s surface, and the slow cooling that occurs there allows large crystals to form. These rocks include: andesite, basalt, dacite, obsidian, pumice, rhyolite, scoria, and tuff. Pictures and brief descriptions of some common igneous rock types are shown on this page.
What type of rock is andesite?
Andesite is an igneous rock that is usually light to dark gray in color. Weathering may cause the color to change to various shades of brown. It is typically found in lava flows produced by stratovolcanoes, which is a composite, conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash.
How is andesite formed from magma?
At times, magma crystallizes into rocks and certain minerals get removed from the rock once the process of crystallization is over. This after a certain point of time results in the formation of andesite. In some instances, magma in the molten form moves in the upward direction towards the predominant crust.
What determines the chemical composition of an andesite?
The amount of silica contained in any rock determines its chemical composition. Geologists use this measure to identify rocks and understand their characteristics. While granite is known to be rich and basalt or rhyolite to be poor in their silica content, andesite rock is said to be having silica content, intermediate to these rocks.
What is the difference between andesite and granite?
While granite is known to be rich and basalt or rhyolite to be poor in their silica content, andesite rock is said to be having silica content, intermediate to these rocks. The name ‘andesite’ is derived from a mountain range, the Andes in South America.