obsidian doesnt crystalize because it was formed under water.
The atoms are not arranged in a regularly repeating crystalline structure.
It is lava glass and does not have a crystaline structure.
Obsidian is a glass, and glasses are by nature non-crystalline.
Obsidian is an igneous silicate rock that cooled so quickly from magma that larger crystals did not have time to form.
because they do not have a glassy luster.
they cooled too quickly
No
Granite is a coarse grained igneous rock without Pyroxene.
Obsidian rocks are cooled very fast, and you cannot see the crystals in them.
Actually, obsidian doesn't have grains at all. Technically obsidian is a glass, which means it has no internal structure. When geologists refer the the grain size of a rock, they mean how big the crystals that make it up are. Since obsidian has no crystals, it therefore has no grain size.
Obsidian is an extrusive rock and is formed from rapidly cooling magma. Obsidian is also known as volcanic glass and one can find only sub-microscopic crystals in it. This is because it was cooled too fastly for large crystals to form. If the material that obsidian consists of were an intrusive rock and had a lot of time to cool down, one would find that it would be composed of easily visible crystals.
most rocks from what i know contain minerals especially sedimentary rocks. and don't all rocks eventually become sedimentary rocks so really don't they all contain minerals to some extent :) hope it helped (by the way i am only a gcse student)
All rock does not contain mineral crystals. Obsidian, or volcanic glass, in particular is a rock that has cooled so quickly from lava that mineral crystals were not able to form.
Granite is a coarse grained igneous rock without Pyroxene.
Obsidian rocks are cooled very fast, and you cannot see the crystals in them.
Actually, obsidian doesn't have grains at all. Technically obsidian is a glass, which means it has no internal structure. When geologists refer the the grain size of a rock, they mean how big the crystals that make it up are. Since obsidian has no crystals, it therefore has no grain size.
Extrusive igneous rock consists of mineral crystals that are not observable with the naked eye. Obsidian is an extrusive igneous rock (volcanic glass) where there technically are no mineral crystals.
Obsidian is an extrusive rock and is formed from rapidly cooling magma. Obsidian is also known as volcanic glass and one can find only sub-microscopic crystals in it. This is because it was cooled too fastly for large crystals to form. If the material that obsidian consists of were an intrusive rock and had a lot of time to cool down, one would find that it would be composed of easily visible crystals.
Obsidian are volcanic Glasses that cool very rapidly. The crystals are not allow to arrange them self's that is why Obsidian has not 3d internal structure. The are Igneous Glasses
That is correct.
Crystal size in these rock types is determined by their rate of cooling. Pegmatites have large crystals due to very slow cooling. Obsidian has microscopic crystals due to almost instantaneous cooling.
most rocks from what i know contain minerals especially sedimentary rocks. and don't all rocks eventually become sedimentary rocks so really don't they all contain minerals to some extent :) hope it helped (by the way i am only a gcse student)
The texture of a rock depends on the rate that it cools. Obsidian cools so quickly that no crystals can form, therefore giving it a glassy texture.
Completely molten rock would not contain any crystals. Most magmas, however, are a mixture of molten and solid crystals of some sort. It is possible that a magma could contain larger crystals of a specific mineral.