This document discusses the mineralogy, textures, types, and occurrences of granite. Granite is a common felsic intrusive igneous rock composed mainly of quartz, feldspar, and mica. It forms large batholiths within the cores of mountain ranges. Granite varies in composition but contains at least 20% quartz and can be classified based on percentages of quartz, alkali feldspar, and plagioclase feldspar. Common types include mica granite, biotite-hornblende granite, and pyroxene granite.

2. Introduction
Mineralogy
Textures
Mode of occurrences
Types
Occurrences
Reference
conclusion

3.  The word "granite" comes from the Latin granum,
 Granite is a common type of
plutonic intrusive, felsic, igneous rock which is granular
and phaneritic in texture.
 This rock consists mainly of quartz, mica, and feldspar.
 By definition, granite is an igneous rock with at least 20% quartz by
volume. Outcrops of granite tend to form rounded massifs. Granites
sometimes occur in circular depressions surrounded by a range of
hills.
 Granite is nearly always massive ,hard and tough, and therefore it has
gained widespread use as a construction stone. The
average density of granite is between 2.65 and 2.75 g/cm3,Melting
temperature is 1215 - 1260 °C.

4. Essential minerals
 Feldspar and quartz are the most important mierals
 Quartz makes up about 10-30%
it is anhedral and occur as phenocryst
 Feldspar-alkali feldspar,orthoclase,microcline
Quartz
Orthoclase
Feldspar

5. Accessory minerals
 Biotite –common mafic mineral in granites.colour varies with fe
content.
 Hornblende-green hornblende seen in calcalkali granites
 amphibole
 Pyroxene
 Hedenbergite
Minor accessories
 Tourmaline,(schorl rock)
topaz,epidote,garnet(almandine,spessartine),apatite,epidote

7.  Granite is classified according to the QAPF diagram for coarse
grained plutonic rocks and is named according to the percentage
ofquartz, alkali feldspar (orthoclase, sanidine, or microcline)
and plagioclase feldspar.
 Granite differs from granodiorite in that at least 35% of the feldspar in
granite is alkali feldspar as opposed to plagioclase; it is the alkali
feldspar that gives many granites a distinctive pink color.
 When a granitoid contains less than 10% orthoclase, it is
called tonalite; pyroxeneand amphibole are common in tonalite. A
granite containing both muscovite and biotite micas is called a binary
or two-mica granite. Two-mica granites are typically high
in potassium and low in plagioclase, and are usually S-type granites
or A-type granites. The volcanic equivalent of granite is rhyolite and
hypabyssal is granophyre(Tyrrell’s classification)

8.  Granite is a phanerocrystalline rock which is
medium to coarse grained.
 They also in holocrystaline, hypidiomorphic,
granular rocks
 Some granites exhibit porphyritic
texture(phenocryst-feldspar), orbicular texture,
graphic(qtz & fldspr), granophyric texture
 Occasionally some individual crystals (phenocrysts)
are larger than the groundmass, in which case the
texture is known as porphyritic. A granitic rock
with a porphyritic texture is sometimes known as
a porphyry. Granites can be pink to gray in color,
depending on their chemistry and mineralogy.

9.  Granites occur as huge batholiths of great dimensions usually
occuring in the cores of mountain
ranges(stocks,bosses,laccoliths)
 The huge bodies does not show any peculiar structure
 Moral jointing is common and rift and grain is also present in
most varieties.
 The basic minerals like biotite,amphibole occur as
seggregations and patches in the granite body.sometimes
parallel arrangement of minerals(foliation) may be seen

10.  Mica granite –the micas,muscovite and biotite together make up
10% of the rock. other accessory minerals are allanite, sphene,
apatite, magnetite and guorite. It is the most abundant type of
granite.
 Biotite hornblende granite – these are next in abundance. These
rocks are somewhat more basic. A few of them carry pyroxenes.
 Pyroxene granite- this type is rare. Biotite and hornblende are
entirely absent here or make up only vary small
amount.clinopyroxene is the chief mafic minerals. Orbicular
granite – it exhibits orbicular structure. The orbicules are made
up of layers of biotite and quartz.
 Granite, pegmatites and aplites – these are very common in
and around a granitic body. The pegmatites have the intergrowth
texture and are very coarse grained. They are store house of a
number of valuable minerals. The aplites are finegrained,
equigranular, allotriomorphic rocks. They occur as contact facies
in a granitic body.

11.  Alkali granite – this is a granite marked by the occurrence of
amphibole and puroxene rich in Na and Fe. The rock is
usuallymade up of sodic and potassic feldspars(75%).perthite
is common. Aegerine and riebeckite are the common mafics.
Accessories are apatite,sphene,zircon,iron ore etc.
 Porphyritic granite – exhibits the porphyritic texture.
Phenocrysts are orthoclase, microcline, perthite.

12.  Granite and granite gneiss are too common in peninsular
India and cover vast areas in Indian geology.
 Typical granite occurrences are Singhbhum granite(Bihar),
Bundelkhand granite(Rajasthan), Erinpura granite, Idar
granite, Closepet granite, Chamundi granite(Karnataka).
 Granites of North arcot and Sankaridrug in Tamilnadu and
granites of Himalayas.alkali granite are seen in Siwana and
Tatanagar.

14.  It is a coarse-grained structure of such a crystalline rock.
 Granite is usually found in the continental plates of the
Earth's crust(magma).
 This rock consists mainly of quartz, feldspar, mica etc
 (Curling) another name for a granite stone.
 A common, coarse-grained, light-colored, hard igneous rock
consisting chiefly of quartz, orthoclase or microcline, and
mica, used in monuments and for building.

15.  Igneous and metamorphic petrology(1962), Francis
J.Turner,McGraw-Hill book company.
 http://en.wikipedia.org/wiki/Granite
 http://www.thefreedictionary.com/granite