You are watching: How is granite different from scoria pumice and obsidian
SCORIA
BASALT
GABBRO


PUMICE
OBSIDIAN
RHYOLITE
GRANITE
PEGMATITE
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PUMICE - cooled down an extremely fast from lava and also has vesicles that suggest that gases to be escaping from the rock - microscopic crystals. OBSIDIAN - also cooled down very fast indigenous lava and that is why the glassy appearance v no crystals. RHYOLITE - is a mixture the crystals the were cooling down progressively inside the magma chamber and also then a volcano explosion lugged them as much as the surface embedded in a soil mass the cooled really quickly. GRANITE - cooled gradually inside the magma chamber fairly closer to the surface - tool size crystals. PEGMATITE - cooled in ~ depth within the magma room - huge crystals. |
Igneous rocks are split into 2 groups: volcanic (extrusive) and PLUTONIC (intrusive). VOLCANIC or EXTRUSIVE igneous rocks come from solidified LAVA. Because LAVA COOLS quickly (outside the Earth"s surface) crystals (grains) execute not have actually time to grow, as such volcanic or extrusive igneous rocks have actually tiny, sometimes microscopic crystals, or castle don"t have actually crystals at all. |
PLUTONIC or EXTRUSIVE igneous rocks come from solidified MAGMA. Due to the fact that MAGMA COOLS slowly (inside the Earth"s surface) crystals (grains) have time to grow, therefore plutonic or intrusive igneous rocks have actually medium size to large crystals. |
In addition igneous rocks according to thier chemical composition room subdivided in to two main groups: MAFIC and also FELSIC. MAFIC igneous rocks room DARK in shade due to your chemical composition which is around 50% silica, Mg (magnesium), Fe (iron) and also Ni (nickel). FELSIC igneous rocks are LIGHT in color due to your chemical ingredient which is around 70% silica, K (potassium), Al (aluminum) with plentiful light mineral (in color) favor quartz and feldspar. |
Igneous rocks have plenty of different textures depending upon rate of cooling (fast or slow). Igneous rocks can be: |
GLASSY - looks prefer a glass and also has no crystals (grains), rocks cooled very fast. VESICULAR - has vesicles (air pockets) developed by escaping gases once the lava reached the Earth"s surface. Crystals room microscopic, rocks cooled fast. APHANITIC - crystals space tiny, rock cooled quick from lava outside the Earth. PORPHYRITIC - mixture of embedded crystals in a well groundmass. Cooled in two stages: magma cools slowly developing medium to huge crystals ad then those installed crystals mixed with Lava come in an explosion that cools really fast. PHANERITIC - medium size to big crystals that room cooled native magma inside the Earth. |
Name of rock = SCORIA Type of rock = VOLCANIC/EXTRUSIVE Composition = MAFIC Cooling price = fast FROM LAVA Texture = VESICULAR | |
Name of absent = BASALT Type of absent = VOLCANIC/EXTRUSIVE Composition = MAFIC Cooling price = rapid FROM LAVA Texture = APHANITIC (tiny Crystals) | |
Name of absent = GABBRO Type of rock = PLUTONIC/INTRUSIVE Composition = MAFIC Cooling price = slow-moving FROM MAGMA Texture = PHANERITIC (medium dimension crystals) | |
Name of rock = OBSIDIAN Type of absent = VOLCANIC/EXTRUSIVE Composition = FELSIC Cooling price = quick FROM LAVA Texture = GLASSY | |
Name of rock = PUMICE Type of absent = VOLCANIC/EXTRUSIVE Composition = FELSIC Cooling price = fast FROM LAVA Texture = VESICULAR | |
Name of rock = RHYOLITE Type of rock = VOLCANIC/EXTRUSIVE Composition = FELSIC Cooling price = TWO phase COOLING: CRYSTALS COOLED SLOWLY and also THEY embedded IN LAVA EJECTED indigenous A VOLCANO Texture = PORPHYRITIC (medium dimension crystals embedded in a fine groundmass) | |
Name of absent = GRANITE Type of rock = PLUTONIC/INTRUSIVE Composition = FELSIC Cooling price = slow-moving FROM MAGMA Texture = PHANERITIC (medium dimension crystals) | |
Name of absent = PEGMATITE Type of rock = PLUTONIC/INTRUSIVE Composition = FELSIC Cooling price = slow FROM MAGMA Texture = PHANERITIC (large size crystals) |
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Magmatic intrusions and also lava operation - There are intrusions that magma asociated through igneous rocks. Some of the intrusions shown above are SILLS and DIKES. |
LAVA operation - igneous material erupted ~ above the Earth"s surface. In a lava flow the height layer will certainly consist of SCORIA (gases escaped conveniently - microscopic crystals), the center layer will certainly consist of BASALT (rock cooled closed to the surface ar - small crystals), and also at the bottom the the intrusion eruption away from the surface ar GABBRO will type (rock cooled underground - large crystals). |
SILLS - space horizontal igneous intrusions that never reach the surface. Because these rocks cool undeground, one can only discover BASALT and GABBRO. BASALT will be cool closer to the Earth"s surface and GABBRO will cool deep underground. | DIKES - are vertical igneous intrusions that never reach the surface and additionally cool underground and there one can find only BASALT and GABBRO. |

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©David Leveson and David Seidemann - civicpride-kusatsu.net college - Earth and also Environmental Sciences