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 5 minerals are in andesite?
Andesite is rich in plagioclase feldspar and amphibole minerals. Quartz and pyroxene minerals may be absent or present in small quantities. Small amounts of mica will be present as biotite or muscovite. Andesite usually does not contain olivine.
Does andesite have a felsic composition?
Andesite possesses a salt and pepper color and texture due to its mafic and felsic composition, making andesite a chemically intermediate rock. Andesite is also characterized as a type of porphyritic rock due to the presence of phenocrysts within a fine-grained matrix.
What are the main minerals in andesite?
Mineral content – groundmass generally of pyroxene ( augite) and plagioclase, possibly with minor amounts of amphibole ( hornblende) and glass; phenocrysts of plagioclase and often pyroxene, occasionally olivine or amphibole.
What are the properties of andesite?
Andesite is usually light to dark gray in colour, due to its content of hornblende or pyroxene minerals. but can exhibit a wide range of shading. Darker andesite can be difficult to distinguish from basalt, but a common rule of thumb, used away from the laboratory, is that andesite has a color index less than 35.
What is the composition of diorite?
Diorite
| Type | Igneous Rock |
|---|---|
| Origin | Intrusive/Plutonic |
| Chemical Composition | Intermediate |
| Color | Approximately half dark, half white minerals |
| Mineral Composition | Sodium – Calcium Plagioclase, Quartz, Hornblende, Biotite |
Is andesite felsic or mafic?
Andesite is INTERMEDIATE in composition between MAFIC and FELSIC rocks. The mixture of mafic and felsic minerals gives the rock a “salt and pepper” appearance. DIORITE – phaneritic rock (large crystals) of both mafic and felsic minerals. ANDESITE – aphanitic rock (small crystals) of both mafic and felsic minerals.
What is the most abundant mineral in andesite?
plagioclase
The primary ingredient of most andesites is andesine, a feldspar of the plagioclase series. Smaller amounts of quartz or minerals rich in iron and magnesium such as olivine , pyroxene, biotite, or hornblende are also present.
What is the density of andesite?
2.40 – 2.80
Densities of Igneous Rocks
| Rock Type | Density Range (g/cm ) |
|---|---|
| Rhyolite | 2.35 – 2.70 |
| Granite | 2.50 – 2.81 |
| Andesite | 2.40 – 2.80 |
| Basalt | 2.70 – 3.30 |
What type of igneous rock is andesite?
extrusive igneous
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.
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 density of andesitic magma?
Density
| Type | Density (kg/m3) |
|---|---|
| Basaltic magma | 2650–2800 |
| Andesitic magma | 2450–2500 |
| Rhyolitic magma | 2180–2250 |
What is the composition of basalt?
Basalts are composed of minute grains of plagioclase feldspar (generally labradorite), pyroxene, olivine, biotite, hornblende, and less than 20% quartz. The mineral nepheline or leucite may associate or proxy the feldspar giving rise to verities with special names.
What is the characteristics of andesite?
Andesite is a dark, fine-grained, brown or greyish intermediate volcanic rock which is a commonly found in lava. The mineral composition of andesite includes biotite, pyroxene, or amphibole.
What texture is andesite?
porphyritic
It is fine-grained (aphanitic) to porphyritic in texture, and is composed predominantly of sodium-rich plagioclase plus pyroxene or hornblende.
What is magma composition?
Magmas can vary widely in composition, but in general they are made up of only eight elements; in order of importance: oxygen, silicon, aluminum, iron, calcium, sodium, magnesium, and potassium (Figure 3.2. 1).
What is andesite used for?
Uses of Andesite 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.
Is andesite an intrusive or extrusive igneous rock?
Andesite is a volcanic (=extrusive igneous) rock with an intermediate to high silica content. It is the eruptive equivalent of diorite,- the same magma that produces diorite as an intrusion will become andesite if erupted.
Is andesite a rock or a mineral?
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. Andesite is a rock typically found in volcanoes above convergent plate boundaries between continental and oceanic plates.
Which intrusive rock has the same composition as andesite?
With the singular exception of quartz,the other phases present represent solid solution series.