Granite is an igneous rock of visible crystalline formation and texture. It is composed of feldspar and quartz with a small amount of mica. Granite is available in a wide variety of colours and textures with a speckled appearance caused by the darker crystals. Granite has greater strength than sandstone, limestone, and marble and is correspondingly more difficult to quarry. It is an important building stone, the best grades being extremely resistant to weathering.