Smoky quartz is also known as ‘Chinese Ink Quartz’ and is a good material for gems. It can be brown, brownish black or black. The cause of the varying colours is unknown. Some think that they are caused by organic material or carbon, but others believe they are due to rock radiation. Smoky quartz is an excellent material for crafts and for making lenses. Famous mining areas include the Alps in Switzerland, Brazil and Madagascar.