Although granite is a good material for building, overflow as the granite in some areas but of radon, a naturally occurring radioactive gas. Radon will make people suffering from lung cancer, Hong Kong 13% the dead of lung cancer deaths are radon concentration.
Quartz and feldspar-rich coarse grain or grain intrusive rocks are the most common plutonic rocks in the Earth's crust, formed by magma deep in the Earth's crust cooled. Due to paving stones and building stone and granite mining was an important industry. Granite veins or rock bed, more representative is irregular rock scale varies greatly. Main components are feldspar, plagioclase and alkali feldspar are usually very rich, the relative abundance of the two into a granite classification based. In most Granites, where the ratio of the two types of feldspar are less than 1/2. Fall into this category of the United States, Central, Eastern and South-Western, South West England, the Baltic shield, France West and Central, Spain most of the granite, and many other areas. Plagioclase greatly exceeds an alkali-feldspar granite, in the United States in some areas in the West common. Content of alkali feldspar than plagioclase granite produced in New England, the United Kingdom and Norway Oslo area in many locations, but is a smaller rock, developed a very wide range in Northern Nigeria. Rock quartz content of less than 20% is not called granite, dark mineral (mafic minerals), the maximum content is about 20% (by volume). Granite is less the main minerals are Muscovite, biotite, hornblende, pyroxene or rare fayalite. Can be produced in any type of biotite in granite, and usually, though sometimes small amounts. Sodium amphibole and pyroxene (iron of sodium sodium amphibole, amphibole, aegirine) are typical of alkaline Granites. If none in the two types of feldspar content much higher than the other, it is unlikely to be the main mineral hornblende, pyroxene; dark mineral is usually of biotite or Muscovite, or both.