Borax, also known as sodium borate, is an acid boron salt with chemical formula Na2B4O7繚10H2O. It is a natural mineral occurring in playa lakes and other evaporitic environments. It has a white powdery appearance, is mostly massive and only rarely adopts the form of prismatic crystals, like in this sample. It is extensively mined and has a variety of uses, like in detergents, ceramics, fire retardants and many more. Provenance of this sample is from Kramer, California and actual width is 145 mm.