Chemical Composition Of Granite And Basalt

Tholeiites vs alkali basalts.

Chemical composition of granite and basalt.

Basalt is an igneous rock that contains more than 45 and less than 52 of sio2 and less than five percent of total alkalies k2o na2o 3. Granite is an intrusive igneous rock which is very hard crystalline and is visibly homogeneous in texture and forms by melting of continental rocks basalt forms when lava reaches the earth s surface near an active volcano. Granite coarse or medium grained intrusive igneous rock that is rich in quartz and feldspar. Average chemical composition of basalt determined by 3594 chemical analyses of basaltic rocks 2 numbers are mass percents recalculated volatile free to total 100.

A worldwide average of the chemical composition of granite by weight percent based on 2485 analyses. Basalt and granite actually have quite a bit in common. Sio 2 49 97 tio 2 1 87 al 2 o 3 15 99 fe 2 o 3 3 85 feo 7 24 mno 0 20 mgo 6 84 cao 9 62 na 2 o 2 96 k 2 o 1 12 p 2 o 5 0 35. Two mica granites are typically high in potassium and low in plagioclase and are usually s type granites or a type granites.

Among other differences the nature of these rocks reveals that basalt is basic in nature whereas granite is acidic in nature. Types of basalt basalt types. Included in this category are most basalts of the ocean floor most large oceanic islands and continental flood basalts such as the columbia. A granite containing both muscovite and biotite micas is called a binary or two mica granite.

It is the most common plutonic rock of the earth s crust forming by the cooling of magma silicate melt at depth. Basalt is volcanic or extrusive forming at the surface while granite is plutonic or intrusive forming beneath the surface. Basalt is common on both earth and other solar system bodies such as the moon and mars while granite is only common on earth and rare elsewhere in the solar system. 70 18 silicon dioxide sio2 14 47 aluminum oxide al2o3 4 11 potassium oxide k2o 3 48 sodium oxide na2o 1 99 calcium oxide cao 1 78 iron ii oxide feo 1 57 iron iii oxide 0 88 magnesium oxide mgo 0 84 water h2o 0 39 titanium dioxide tio2 0 19 diphosphorus pentoxide p2o5 and 0 12 manganese oxide mno.

This composition is as follows. A magma the earth gets very hot just below the surface and there is lots of liquidrock available. Both are made up of minerals from the silicate group so both have large amounts of silicon. Basalt is mafic while granite is felsic.

The chemical composition of granite is typically 70 77 silica 11 13 alumina 3 5 potassium oxide 3 5 soda 1 lime 2 3 total iron and less than 1 magnesia and titania. Tholeiitic basalt is relatively rich in silica and poor in sodium. Basalt has a strict chemical definition. Of the two basalt is darker and consists of fine grained minerals such as magnesium and iron while granite is lighter and consist of feldspar and quartz.