Is Granite A Crystalline Rock

The word granite comes from the latin granum a grain in reference to the coarse grained structure of such a completely crystalline rock.

Is granite a crystalline rock.

Because obsidian is metastable at the earth s surface over time the glass becomes fine grained mineral crystals no obsidian has been found that is older than the cretaceous period. Granite and marble are the two most used natural stones with the inter crystalline technological coloring process. Granite is composed mainly of quartz and feldspar with minor amounts of mica amphiboles and other minerals. Granite is a light colored igneous rock with grains large enough to be visible with the unaided eye.

Batholiths composed dominantly of granitic rock with little in the way of metamorphic rock as shown in fig. Minerals are naturally occurring solids. This transformation of obsidian is accelerated by the presence of water. Yes it is crystalline hard and has visible grains.

Intrusive igneous rocks those that congeal at depth are virtually always crystalline whereas extrusive igneous rocks or volcanic rocks may be partly to entirely glassy. Crystalline rock any rock composed entirely of crystallized minerals without glassy matter. It consists of feldspar which is usually a potash feldspar and oligoclase. But beyond that it is a plutonic igneous rock formed at great depths from an original fluid and not from the metamorphism of another rock.

On the other end of the spectrum is sandstone with its large individual sand grains. Granite is an igneous rock of visible crystalline formation and texture. The resulting coloring and designs are permanent unique and are guaranteed to be the focal point of interest in any home or business. In both cases the rocks are capable of producing a monotonous somewhat random less predictable landscape relative to what might be seen in sedimentary rocks.

Strictly speaking granite is an igneous rock with between 20 and 60 quartz by volume and at least 35 of the total feldspar consisting of alkali feldspar although commonly the term granite is used to refer to a wider range of coarse grained igneous rocks containing quartz and feldspar. Crystalline rocks with a similar composition include granite and rhyolite. To geologists true granite is a far more specific rock type. In crystalline rocks like granite which have tight interlocking mineral grains porosity is normally quite low less than 1 percent.

Crystalline rocks generally fit into one of two categories. Granite does not belong to any crystal structure group because granite is a rock not a mineral and only minerals can be grouped by crystal form or shape.