What is the granite?

Granite is an igneous rock and is formed from magma.Granitic magma has many potential origins but it must intrude other rocks. Most granite intrusions are emplaced at depth within the crust,usually greater than 1 mile up to 30 miles depth within thick continental crust.

Granite consists largely of alkali feldspar,quartz and calcic albite.Its average grain size is 0.04-1.0 in(1-25mm) finer-grained rocks of this composition include rhyolite and aplite.By definition granite containing 80-100% by volume quartz,alkali feldspar and plagiochase minerals.Granite is formed by slow crystalization of deep igneous intrusion.Depending on the feldspar present granite may be pink,dark,gray or light gray.It is commonly believed to have solidified from molten rock (magma) under pressure.However, some granite show no contacts with surrounding wall rock,but instead gradually grade into metamorphic rock.others show relic features found in sediments.Some granite are the oldest known rocks on earth,others were formed during younger geologic periods.Crystallized at depth,granite masses are expozed at the earth's surface by crustal movement or by erosion of overlying rocks.

Granite is a normal,geological, source of radiation in the natural environment.However,in the majority of cases,although granite is a source of natural radiation as compared to other rocks it is not pften an acute health threat or significant risk factor.