What are the properties of andesite?
What are the properties of andesite?
Characteristics and Properties of Andesite Rock Andesite, together with pyroxene, consists of plagioclase feldspar. In addition, it may contain hornblende. The minerals that this rock can contain are apatite, garbet, ilmenite, biotite, magnetite, zircon. It may also contain trace amounts of alkali feldspar.
How is porphyritic andesite formed?
Porphyritic texture — andesite: This is an extrusive igneous rock. The magma from which it formed cooled slowly for a while deep below the surface (forming the large crystals), then finished cooling very quickly when it was ejected at the surface, forming the fine-grained groundmass.
What is the composition of porphyritic andesite?
Porphyritic Andesite
| Type | Igneous Rock |
|---|---|
| Chemical Composition | Intermediate |
| Color | Dark Green |
| Mineral Composition | Sodium – Calcium Plagioclase, Pyroxene, Hornblende |
| Miscellaneous | Hornblende Phenocrysts in an aphanitic (fine-grained) groundmass |
What is the process of formation for andesite?
How was it formed? 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 does a porphyritic rock look like?
Porphyritic – This texture describes a rock that has well-formed crystals visible to the naked eye, called phenocrysts, set in a very fine grained or glassy matrix, called the groundmass.
What is the texture of andesite?
It is fine-grained (aphanitic) to porphyritic in texture, and is composed predominantly of sodium-rich plagioclase plus pyroxene or hornblende.
What does a porphyritic texture indicate?
Porphyritic texture indicates the magma body underwent a multi-stage cooling history, cooling slowly while deep under the surface and later rising to a shallower depth or the surface where it cooled more quickly.
What minerals are in andesite porphyry?
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.
Why is andesite used for construction?
Andesite stones are more durable than calcium rocks and can be much more easy to handle than other volcanic rocks.
What does a porphyritic texture suggest about how an igneous rock formed?
What does a porphyritic texture indicate about the cooling history of an igneous rock? It indicates that crystals were formed at depth (slow cooling) and then the magma moved to a shallow depth or erupted (fast cooling).
