Why Is The Crystal Size Of Granite Different From Basalt

Basalt and granite are two types of igneous rocks that we can find on earth.

Why is the crystal size of granite different from basalt.

Granite is a felsic rock meaning that it has a high silicon content. Basalt is an aphanitic fine grained igneous rock that is relatively low in silica and alkali metals it has less than 10 feldspathoid by volume with at least 65 of the rock consisting of feldspar in the form of plagioclase this places basalt in the basalt andesite field of the qapf diagram basalt is further distinguished from andesite by its silica content of less than 52. Basalt as a mafic rock contains more calcium oxide manganese oxide and iron compounds than granite. Granite and basalt have different compositions and form under different circumstances.

The crystals in granite being intrusive in nature will be larger than those in basalt an extrusive igneous rock. Basalt is an igneous volcanic rock that forms commonly in oceanic crust and parts of. Basaltic crust is dark and thin and heavy while granite is light and accumulates. If magma cools quickly for example when basalt lava erupts from a volcano then many crystals form very quickly and the resulting rock is fine grained with crystals usually less than 1mm in size.

If magma is trapped underground in an igneous intrusion it cools slowly because it is insulated by the surrounding rock. Though granite and basalt are of different origin but broadly granite is a lower temperature rock as compared to basalt. Basalt can form in a few days to months whereas granite plutons can take millions of years to cool and harden. Basalt wikipedia wikimedia foundation 13 sept.

The key difference between basalt and granite is that basalt is mostly occurring on ocean floors while granite is in the crust of the earth in all continents. Its high iron content gives it magnetic properties and it may show signs of rust when exposed to air. Granite is coarser grained as compared to basalt which is extremely fine grained. In granite the crstals are so big they ussually take up at least 70.

It is mostly made out of quartz mica and feldspar. Basalt is more common in oceanic crust while granite is more common in continental crust. The crystal size is indicative of the time required for growth of the crystal in the igneous melt. It wants to be there and heat is the key which unlocks the door.

How big are the crystal in granite. Summary basalt vs granite. The trick is to heat the basalt back up again so it can melt and give the iron another shot at the core.