25 - Quartzite

Hello friends, Welcome to the Rock Repository at the Department of Geology, Shivaji Science College, Nagpur.

I am quartzite, a hard, non-foliated, metamorphic rock formed due to the metamorphism of pure quartz sandstone. I am formed when a quartz rich sandstone gets altered by the action of heat, pressure and chemical activity of metamorphism. I am composed of 90 percent quartz grains with some other minor elements and in some cases I contain up to 99 percent quartz grains. I am usually light colored (white or gray) but the addition of impurities imparts a red, blue, green, orange or purple color to me. I tend to have a sugary appearance and a glassy(vitreous) luster. The interlocking, crystalline, granuloblastic texture found in me makes me a hard, tough and a durable rock and very resistant to chemical weathering. The quartz content found in me gives me a hardness of about seven on the Mohs Scale of Hardness. I am mostly found in areas of mountain building events at convergent plate boundaries where sandstone is deposited at a continental plate and later on gets metamorphosed due to the intense pressure of a plate collision and often by deep burial. I am an important rock type in folded mountain ranges throughout the world. Because of my weathering resistant nature, I am typically found at the crests of mountain ranges and covering their flanks as large boulders.  I am used as a decorative stone to cover walls, roofing tiles, as flooring and stairsteps. I am also used in making bricks and other building materials. Crushed variety of me is also used in road constructions. Thank you for visiting.