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.
Simply so, 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.
Is andesite a density? Andesites with it’s normal mineralogy generally have densities between 2.6 to 2.8.
Subsequently, What is andesite used for?
Uses – can be used as aggregate, fill etc. in the construction and roading industries (often not ideal for concrete aggregate because of high silica content).
Does andesite contain quartz?
Andesite is a fine-grained, extrusive igneous or volcanic rock. … Andesite forms from magma that contains less quartz (silica) than rhyolite but more than basalt. It is therefore often referred to as ‘intermediate’ in composition.
What is an andesitic volcano? Andesite is a gray to black volcanic rock with intermediate silica content, typical for lava domes and stratovolcanoes in subduction zones. Andesite is an igneous volcanic rock containing between about 52 and 63 weight % silica (SiO2).
What type of rock is 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 black mineral in andesite? The black phenocrysts are hornblende, the white crystals are plagioclase. The grayish areas between the phenocrysts display some tiny mineral crystals but are mostly too fine-grained to see any crystal grains.
What is the most common mineral in andesite?
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 viscosity of andesitic? Andesitic magmas, in particular, have a wide range of magma viscosities, from 102 to 107 Pa s, which is due to a wide range in phenocryst contents from 0 (phenocryst‐free andesitic melt) to ∼50 vol % (50 vol % rhyolitic melt + 50 vol % phenocrysts).
What is the solidified rock of andesitic?
Viscosity of Magmas
| Summary Table | ||
|---|---|---|
| Magma Type | Solidified Rock | Viscosity |
| Basaltic | Basalt | Low |
| Andesitic | Andesite | Intermediate |
| Rhyolitic | Rhyolite | High |
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Why is andesitic lava viscous? Andesitic lava is an example of a high viscosity lava whereas balastic lava has a low viscosity, so is more runny. High silica content in the andesitic lava contributes to causing this high viscosity and low silica content in the basaltic lava means it is of a lower viscosity.
What type of rock is gneiss?
gneiss, metamorphic rock that has a distinct banding, which is apparent in hand specimen or on a microscopic scale. Gneiss usually is distinguished from schist by its foliation and schistosity; gneiss displays a well-developed foliation and a poorly developed schistosity and cleavage.
What type of rock is phyllite?
Phyllite
| Type | Metamorphic Rock |
|---|---|
| Texture | Foliated; Fine-grained |
| Composition | Muscovite, Biotite, Quartz, Plagioclase |
| Index Minerals | |
| Color | Shiny Gray |
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 |
What are the 3 different rock types?
There are three kinds of rock: igneous, sedimentary, and metamorphic. Igneous rocks form when molten rock (magma or lava) cools and solidifies. Sedimentary rocks originate when particles settle out of water or air, or by precipitation of minerals from water. They accumulate in layers.
Is andesite a volcanic?
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.
Is basaltic magma fluid or viscous? Thus, basaltic magmas tend to be fairly fluid (low viscosity), but their viscosity is still 10,000 to 100,0000 times more viscous than water. Rhyolitic magmas tend to have even higher viscosity, ranging between 1 million and 100 million times more viscous than water.
What is the silica content of andesitic?
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.
What volcano has andesitic magma? Shield volcanoes are formed by basaltic magma, typically above a mantle plume, whereas the stratovolcanoes (sometimes referred to as composite volcanoes) are formed by andesitic/rhyolitic magma.
Where do andesitic lavas erupt?
Andesite commonly erupts from stratovolcanoes, where they form small-volume flows that typically advance only short distances down the flanks of a volcano. The two examples shown here are short andesite flows advancing down the slope of the Lascar volcano in Chile, and the Colima volcano in Mexico.
What is the origin of andesitic lava? Granitic, or rhyolitic, magmas and andesitic magmas are generated at convergent plate boundaries where the oceanic lithosphere (the outer layer of Earth composed of the crust and upper mantle) is subducted so that its edge is positioned below the edge of the continental plate or another oceanic plate.
What is the chemical composition of andesitic?
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 difference between andesitic and basaltic lava? Basaltic magma is high in iron, magnesium, and calcium but low in potassium and sodium. It ranges in temperature from about 1000oC to 1200oC (1832oF to 2192oF). Andesitic magma has moderate amounts of these minerals, with a temperature range from about 800oC to 1000oC (1472oF to 1832oF).
How do basaltic rhyolitic and andesitic differ?
BASALTIC magmas have a LOW SILICA content (45-55%) and referred to as MAFIC in composition. RHYOLITIC magma contains more than 65% SILICA and is referred to as FELSIC. ANDESITIC magma is INTERMEDIATE in composition (55-65% SILICA).
How hard is gneiss rock? Take comfort in knowing that gneiss can withstand heavy use; it is made up of minerals in the 6-7 range on Mohs scale, meaning it’s harder than glass and about the same hardness as steel.
What is gneiss texture? The « gneissic texture » refers to the segregation of light and dark minerals. It is indicative of high-grade metamorphism where the temperature is high enough, say 600-700 °C, so that enough ion migration occurs to segregate the minerals.
What is properties of gneiss?
Gneiss is a medium- to coarse-grained, semischistose metamorphic rock. It is characterized by alternating light and dark bands differing in mineral composition (coarser grained than schist). The lighter bands contain mostly quartz and feldspar, the darker often contain biotite, hornblende, garnet or graphite.
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