How do you identify a pegmatite rock?

Published by Charlie Davidson on

How do you identify a pegmatite rock?

They are extreme because they contain exceptionally large crystals and they sometimes contain minerals that are rarely found in other types of rocks. To be called a “pegmatite,” a rock should be composed almost entirely of crystals that are at least one centimeter in diameter.

What is the description of pegmatite?

PEGMATITE is a common plutonic rock, of variable texture and coarseness, that is composed of interlocking crystals of widely different sizes. The most spectacular pegmatites contain abnormally large crystals mixed with medium sized and smaller crystals. Crystals up to many meters long have been reported.

What is the texture of pegmatite rock?

Pegmatite is an igneous rock that form end of the stage a magma’s crystallization. Pegmatites contain exceptionally large crystals and they contain rarely minerals than other types of rocks. Perthite feldspar within a pegmatite often shows gigantic perthitic texture visible to the naked eye.

What kind of rock is pegmatite granite?

crystalline igneous rocks
Pegmatites are unusually coarse-grained crystalline igneous rocks, usually of granitic composition and characterized by interlocking crystals several centimeters up to tens of meters in length.

What is the color of pegmatite rock?

Part of Hall of Planet Earth. This granite pegmatite illustrates the growth of extremely large crystals from a magma. It is composed of large feldspar (white) and biotite mica (silver-black) crystals in a groundmass of small crystals of quartz (gray), microcline, and albite (both white).

What is the color of pegmatite?

Pegmatite in which the main ingredients are biotite mica (black), microcline (pink), oligoclase (white), and quartz (gray). The rock has a monzogranitic composition.

Is glassy a texture?

If a rock looks like a block of (colored) glass, with no visible mineral crystals, it has a glassy texture. Superficially, a glassy texture suggests cooling that was so extremely fast that no crystals could form. Here are three different types of a glassy volcanic rock called obsidian. …

How is pegmatite rock formed?

A pegmatite is an igneous rock, formed by slow crystallization at high temperature and pressure at depth, and exhibiting large interlocking crystals usually greater in size than 25 mm (0.98 in).

What can diorite turn into?

It is used as a base material in the construction of roads, buildings, and parking areas. It is also used as a drainage stone and for erosion control. In the dimension stone industry, diorite is often cut into facing stone, tile, ashlars, blocking, pavers, curbing, and a variety of dimension stone products.

What type of rock is chalk?

Chalk, a sedimentary rock, is a soft form of limestone that is not well cemented and thus is often powdery and brittle.

What type of rock is tonalite?

The intrusive igneous rock is often a chief component of extensive batholiths, such as the Shasta Valley batholith of California. Sometimes alternatively referred to as quartz diorite, tonalite is typically comprised of plagioclase feldpar, alkali feldspar, and more than 20 percent quartz.

Where can you find a pegmatite rock?

A pegmatite is an igneous rock, formed underground, with interlocking crystals usually larger than 2.5 cm in size. Most pegmatites are found in sheets of rock near large masses of igneous rocks called batholiths. The word pegmatite derives from Homeric Greek, πήγνυμι, which means “to bind together”, in reference to the intertwined crystals of quartz and feldspar in the texture known as graphic granite. Most pegmatites are composed of quartz, feldspar and mica, having a similar

What is a fun fact about the pegmatite rock?

Interesting Pegmatite Facts: Crystals of pegmatite grow large because of the extreme conditions of crystallization. Basically, the presence of residual water has allowed the magma to cool slowly to permit coarse crystal growth. Complex pegmatites result because of the presence exotic volatiles such as chlorine, fluorine , and carbon dioxide.

What are the physical properties of pegmatite rock?

There are various physical properties of Pegmatite like Hardness, Grain Size, Fracture, Streak, Porosity, Luster, Strength etc which defines it. The physical properties of Pegmatite rock are vital in determining its Pegmatite Texture and Pegmatite Uses.

Is pegmatite an intrusive or extrusive?

Pegmatite is called an intrusive igneous rock because it forms when magma solidifies under the Earth’s surface. In contrast, when magma solidifies outside the Earth’s surface, it forms an extrusive igneous rock. The process by which pegmatite is formed explains why its crystals are so large:

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