Table of Contents
What is the composition of andesite?
Andesite most commonly denotes fine-grained, usually porphyritic rocks; in composition these correspond roughly to the intrusive igneous rock diorite and consist essentially of andesine (a plagioclase feldspar) and one or more ferromagnesian minerals, such as pyroxene or biotite. …
What is the chemical composition of diorite?
Diorite
| Type | Igneous Rock |
|---|---|
| Chemical Composition | Intermediate |
| Color | Approximately half dark, half white minerals |
| Mineral Composition | Sodium – Calcium Plagioclase, Quartz, Hornblende, Biotite |
| Miscellaneous | Salt and Pepper Appearance |
Does andesite have a felsic composition?
ANDESITE – aphanitic rock (small crystals) of both mafic and felsic minerals.
Which chemical element gives andesite its dark Colour?
Basaltic andesite, with a content of 52% to 57% silica, is represented by the O1 field of the TAS classification but is not a recognized type in the QAPF classification. Andesite is usually light to dark gray in colour, due to its content of hornblende or pyroxene minerals.
What is the chemical formula of obsidian?
The chemical composition of obsidian samples from 28 sources in Western America is that of a high alumina glass (ca. 12 wt% Al2O3) with a silica content exceeding that of normal granite.
What are the properties of andesite?
It is fine-grained (aphanitic) to porphyritic in texture, and is composed predominantly of sodium-rich plagioclase plus pyroxene or hornblende. Andesite is the extrusive equivalent of plutonic diorite. Characteristic of subduction zones, andesite represents the dominant rock type in island arcs.
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 .
What does andesite look like?
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,…
Where is andesite found?
The name “Andesite” is derived from the Andes Mountains of South America, where the rock was originally discovered. However, the rock forms from subduction zones all around the world. These zones can be found in Central America, Mexico, Japan, Indonesia, the Philippines, New Zealand, the US Pacific Northwest, and the Caribbean alike.
Do granite and rhyolite have the same chemical composition?
Although granite and rhyolite are chemically similar , granite often contains the mineral muscovite. Muscovite is rarely found in rhyolite. Rhyolite may contain much more of the element potassium than sodium, but this imbalance is uncommon in granite.