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Very large silicate mineral grains (crystals) indicate extremely fast, in-melt transport of the mineral constituents to the growing crystals. We know that pegmatite magmas are small volume, relatively low temperature melts that are extremely rich in water and other dissolved volatiles. The volatiles promote very fast rates of material transfer, thus accounting for rapid growth of very large crystals.
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What ore deposits and gem crystals are often associated with?
Pegmatites.
What kind of rock formation is sometimes filled with crystals?
Geodes are rocks that are lined or filled with crystals. Pegmatites are rock formations that often exhibit extremely large crystals. Just a note--all rocks are composed of mineral crystals, with few exceptions. The crystals in some, however are just too small to see.
Which igneous rocks would contain the largest crystals?
Pegmatite. Individual crystals can be as large as a bathtub. Pegmatites are the last rocks to crystallize from a solidifying body of magma. The large size of the crystals results from the slow rate of cooling and the presence of large amounts of water dissolved in the magma.
What are minerals that can form into small-teardrop formations?
When minerals are mined and are found in a teardrop formation, they are referred to as pegmatite's Some examples of pegmatite's are Topaz and Tourmaline.
Are large crystals found in diorite?
diorite crystals are large and andesite crystals are small
Are igneous rocks formed from smalll minerals?
Not necessarily. Intrusive igneous rocks, especially pegmatites, can have large crystals.
How do the crystals in the pegmatites form?
slow cooling of gaseous magma
What ore deposits and gem crystals are often associated with?
Pegmatites.
Explain pegmatite is coarse grained with large crystals basalt is fine grained with small crystals and obsidian has no crystals?
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.
What kind of rock formation is sometimes filled with crystals?
Geodes are rocks that are lined or filled with crystals. Pegmatites are rock formations that often exhibit extremely large crystals. Just a note--all rocks are composed of mineral crystals, with few exceptions. The crystals in some, however are just too small to see.
Which igneous rocks would contain the largest crystals?
Pegmatite. Individual crystals can be as large as a bathtub. Pegmatites are the last rocks to crystallize from a solidifying body of magma. The large size of the crystals results from the slow rate of cooling and the presence of large amounts of water dissolved in the magma.
Why are Pegmatite crystals so big?
They are associated with the late stages of granite intrusions and the minerals formed in pegmatites literally had the time to enjoy the benefits of a slow crystallization process from a rich chemical stew produced by the cooling granite.
What are minerals that can form into small-teardrop formations?
When minerals are mined and are found in a teardrop formation, they are referred to as pegmatite's Some examples of pegmatite's are Topaz and Tourmaline.
Are large crystals found in diorite?
diorite crystals are large and andesite crystals are small
Why are exceptionally large mineral crystals found in pegmatite?
They are associated with the late stages of granite intrusions and the minerals formed in pegmatites literally had the time to enjoy the benefits of a slow crystallization process from a rich chemical stew produced by the cooling granite. For an alternate hypothesis, see the link below.
Do igneous rocks have small crystals large crystals or no crystals?
It depends on the type of igneous rock. Intrusive igneous rocks such as granite have large crystals, extrusive igneous rocks may have small crystals as in basalt or no crystals as in pumice.
What does the presence of large crystals tell you about the rocks' formation?
Larger crystals suggest slower formation. Crystals would have less time to grow if cooled quickly, and so would be smaller.
