Placer mining. Placers are unconsolidated deposits of detrital material containing valuable minerals. The natural processes by which they form range from chemical weathering to stream, marine, and wind action. Typical minerals recovered in placers are gold, tin, platinum, diamonds, titaniferous and ferrous iron sands, gemstones (rubies, emeralds, and sapphires), and abrasives (rutile, zircon
Baryte or barite (UK / b r t /, / b r a t / ) is a mineral consisting of barium sulfate (Ba S O 4). Baryte is generally white or colorless, and is the main source of barium.The baryte group consists of baryte, celestine (strontium sulfate), anglesite (lead sulfate), and anhydrite (calcium sulfate). Baryte and celestine form a solid solution (Ba,Sr)SO 4.