granite

SRI Petrography ID: 18

Schärdinger
Upper Austria

Granito verde di San Lorenzo

Dekorgestein und Baugesteinsammlung
Area of usage: ancient Rom
NHM-Inv.-No.: F2296
SRI-No.: 77-18

Names

[de] Granit
[en] granite

Description

coarse grained, light coloured igneous rock with variable colour and grain size. Consists of feldspar, quartz and mica, additionally amphibole or pyroxenes possible.
The International Union of Geological Sciences (IUGS) subcommission defines granite as containing 80–100 Vol.% by volume quartz, alkali feldspar, and plagioclase and 20–0 Vol.% accessory minerals. The three essential minerals must include 20–60 Vol.% quartz, and alkali feldspar must constitute 65–90% of the total feldspar.
Granites may be divided into three major types: alkaline, peraluminous, and calc-alkaline. Calc-alkaline granites typically are biotite or biotite-hornblende granites, some contain augite (pyroxene), and sphene is a common accessory.

Color

variable, often pink, dark gray, light gray, white (depending on the present feldspar)

Grain Size

coarse grained

Texture

even texture

Minerals

quartz and feldspar, mica and additional minerals like hornblende, pyroxene, sphene, garnet, cordierite, etc.

Occurences

granite occurs worldwide in continental crust, e.g. Egypt (esp. the well known red Aswan granite), India

Comments

Variety alkali feldspar granite: alkali feldspar constitutes 90–100% of its total feldspar.
In the building stone industry the term “granite” is used for any crystalline silicate rock having visible grains; this includes gneiss as well as other igneous rocks that are not granite in the strict sense.

Classification

Class

IGNEOUS ROCKS

Broader Terms

coarse-grained crystalline rocks

Narrower Terms

Armenia-granite

Austria-granite

Brazil-granite

Czech-Republic-granite

Egypt-granite

Finland-granite

France-granite

Germany-granite

Greece-granite

Italy-granite

Russia-granite

Seychelles-granite

Spain-granite

Sweden-granite

USA-granite