How are pumice and obsidian related?
Obsidian and pumice are both volcanic glass rocks. Remember that lava that is ejected from a volcano is "pyroclastic". The only thing that makes pumice different from obsidian is that gas bubbles were trapped in the volcanic glass as it was ejected from the volcano. Pumice is essentially foamy obsidian.
What is the texture of obsidian and pumice?
Both pumice and obsidian are glassy (amorphous,non-crystalline, and having non-discernable mineral proportions).
What rock forms similar to obsidian?
Most obsidians have a composition similar to rhyolite and granite. Granites and rhyolites can form from the same magma as obsidian and are often geographically associated with the obsidian. Rarely, volcanic glasses are found with a composition similar to basalt and gabbro. These glassy rocks are named "tachylyte."
Are pumice and obsidian felsic?
Obsidian is an extrusive volcanic rock formed by the rapid cooling of high viscosity magma. It is recognized by its glassy texture. Silicic magmatic compositions and fast cooling rates prevent the formation of crystals even at the microscopic scale. Pumice is a low-density, light-colored felsic volcanic rock.
What is the difference between obsidian pumice and scoria?
Scoria is another volcanic rock with holes in it, though the amount of volcanic material between the holes is usually thicker, or more compacted, in scoria than in pumice. It is often dark red. Obsidian is a shiny, dark, dense volcanic glass. It was formed from lava that cooled very quickly.
What is pumice made up of?
Pumice is composed of highly microvesicular glass pyroclastic with very thin, translucent bubble walls of extrusive igneous rock.
What texture is pumice?
Vesicular Pumice
| Type | Igneous Rock |
|---|---|
| Texture | Vesicular |
| Origin | Extrusive/Volcanic |
| Chemical Composition | Felsic |
| Color | White |
What type of rock is pumice?
Pumice is pyroclastic igneous rock that was almost completely liquid at the moment of effusion and was so rapidly cooled that there was no time for it to crystallize. When it solidified, the vapours dissolved in it were suddenly released, the whole mass swelling up into a froth that immediately consolidated.
How is pumice formed?
Pumice is formed when volcanoes erupt explosively. It comes from the same kind of magma which would form granite or rhyolite, that is, a magma that contains lots of silica (quartz).
What composition is obsidian?
obsidian, igneous rock occurring as a natural glass formed by the rapid cooling of viscous lava from volcanoes. Obsidian is extremely rich in silica (about 65 to 80 percent), is low in water, and has a chemical composition similar to rhyolite. Obsidian has a glassy lustre and is slightly harder than window glass.
What do pumice and scoria have in common?
What do pumice and scoria have in common? They both exhibit a vesicular texture.
What is pumice made of?
Pumice is formed when volcanoes erupt explosively. It comes from the same kind of magma which would form granite or rhyolite, that is, a magma that contains lots of silica (quartz). Magma with lots of silica is usually thick and sticky.
What is obsidian made of?
Rondi: Everyone, meet Obsidian , an igneous rock that from melted rock, or magma. Obsidian is an "extrusive” rock, which means it is made from magma that erupted out of a volcano. If it was an igneous rock that formed from magma underground and did not erupt, it would have been called an "intrusive" rock.
What texture is obsidian?
Glassy Obsidian
| Type | Igneous Rock |
|---|---|
| Texture | Glassy |
| Origin | Extrusive/Volcanic |
| Chemical Composition | Felsic |
| Color | Black |
What type of rock is obsidian?
Rondi: Everyone, meet Obsidian , an igneous rock that from melted rock, or magma. Obsidian is an "extrusive” rock, which means it is made from magma that erupted out of a volcano. If it was an igneous rock that formed from magma underground and did not erupt, it would have been called an "intrusive" rock.
Is Obsidian a sedimentary rock?
Obsidian is an igneous rock occurring as a natural glass that is formed by the rapid cooling of viscous lava from volcanoes.
How is obsidian formed?
Obsidian is an "extrusive” rock, which means it is made from magma that erupted out of a volcano. If it was an igneous rock that formed from magma underground and did not erupt, it would have been called an "intrusive" rock.
Where is obsidian formed?
volcanoes Obsidian is produced from volcanoes when felsic lava cools and freezes without sufficient time for crystal growth. It is commonly found in areas where the cooling of lava was rapid—such as at the margins of the lava flows and in places where the lava entered a lake or sea.