Black sand is sand that is black in color. One type of black sand is a heavy, glossy, partly magnetic mixture of usually fine sands containing minerals such as magnetite, found as part of a placer deposit. Another type of black sand, found on beaches near a volcano, consists of tiny fragments of basalt.
Black sand on a beach in Southern Iceland
Closeup of black sand from a beach in Maui, Hawaii
Black sand beach in Waianapanapa Park, Hawaii
Black sand and icebergs on a beach in Iceland
Magnetite is a mineral and one of the main iron ores, with the chemical formula Fe2+Fe3+2O4. It is one of the oxides of iron, and is ferrimagnetic; it is attracted to a magnet and can be magnetized to become a permanent magnet itself. With the exception of extremely rare native iron deposits, it is the most magnetic of all the naturally occurring minerals on Earth. Naturally magnetized pieces of magnetite, called lodestone, will attract small pieces of iron, which is how ancient peoples first discovered the property of magnetism.
Magnetite from Bolivia
Magnetite is one of the very few minerals that is ferrimagnetic; it is attracted by a magnet as shown here
Magnetite and other heavy minerals (dark) in a quartz beach sand (Chennai, India).
Octahedral crystals of magnetite up to 1.8 cm across, on cream colored feldspar crystals, locality: Cerro Huañaquino, Potosí Department, Bolivia
