Igneous Granite 35 Olivine

3 4 classification of igneous rock as has already been described igneous rocks are classified into four categories.

Igneous granite 35 olivine.

Synonymous with ferromagnesian which refers to biotite amphibole pyroxene olivine and fe ti oxides. Typically that means they are larger than about 0 5 millitmeres mm the thickness of a strong line made with a ballpoint pen. Granite is a medium tocoarse grained acid igneous rock with essential quartz 20 and feldspar where alkali feldspar constitutes between 100 and 35 of the feldspars and minor mafic minerals. V 308 67 den calc 3 30.

The igneous rock granite. The granite of pikes peak in colorado is an example of such a fayalite granite. Felsic intermediate mafic and ultramafic based on either their chemistry or their mineral composition. Still more mafic a mineral is olivine.

85 olivine 15 pyroxene. Granite b gabbro c basalt d rhyolite 35 the photograph below shows actual crystal sizes in a. Granite granite is a medium tocoarse grained acid igneous rock with essential quartz 20 and feldspar where alkali feldspar constitutes between 100 and 35 of the feldspars and minor mafic minerals. 20 olivine 45 pyroxene 35 plagioclase feldspar.

10 pyroxene 20 amphibole 10 mica 60 plagioclase feldspar. The diagram in figure 3 4 1 can be used to help classify igneous rocks by their mineral composition. Normally olivine and quartz never appear together but in exceptionally sodium rich granite the iron bearing variety of olivine fayalite is compatible. Hornblende and biotite are the commonest mafic minerals however muscovite is also frequently encountered.

Olivine 28 for an igneous rock to be classified as rhyolite it must be light colored be fine grained and contain. Two minerals found in basalt but not granite. Igneous rocks are also classified according to their textures. Most abundant dark coloured mineral found in basalt.

Mnemonic based on magnesium and ferrous ferric. A a high concentration of silicon and a low. Very rich in mg. Mnemonic based on feldspar and silica.

General name given to igneous rocks formed within the earth s crust. Also applies to rocks containing abundant feldspathoids such as nepheline. A 4 78 b 10 25 c 6 3 z 4. I worked it out by remembering my basic igneous rock percentages.

Gabbro is a dark medium to coarse grained intrusive igneous rock composed of calcium plagioclase pyroxene and minor olivine but no quartz.