Sylvinite is a sedimentary rock made of a mechanical mixture of the minerals sylvite (KCl, or potassium chloride) and halite (NaCl, or sodium chloride). Sylvinite is the most important source for the production of potash in North America, Russia and the UK. Most Canadian operations mine sylvinite with proportions of about 31% KCl and 66% NaCl with the balance being insoluble clays, anhydrite and in some locations carnallite. Other deposits of sylvinite are in Belarus, Brazil, France, Germany, Kazakhstan, Slovakia and Spain.