The Illustrated Encyclopedia of Rocks, Minerals & Gemstones

"A detailed introduction explains the formation and classification of the many types of rock, mineral and gemstones, with clear photographs of some of the world's most bizarre and beautiful examples. Expertly written text describes the impact of factors such as time, weather and water erosion on the development of rocks and minerals in the landscape, and the part played by natural phenomena such as volcanoes and earthquakes. It clarifies contact with heat and pressure can affect external characteristics, and prompt the metamorphosis of one rock into another."--