Feldspar is a general term for one of the most abundant group of minerals on Earth. Together the different varieties account for more than half of the Earth’s crust. These rock forming minerals occur worldwide and as well as being the major componement of most igneous rocks, are also found in sedimentary and metamorphic rocks. Feldspar has also been found on the moon and in meteorites.
The variation in colour of feldspar depends on the impurities present within the crystal structure.
As well as being widely used in industry, some types of feldspar are also popular for lapidary purposes and in particular gemstones. Amazonite, moonstone, labradorite, and sunstone are possibly the four best known varieties of feldspar.