Non-metal minerals include limestone, marble, fluorspar, silica, pearlite, bentonite etc. Important mineral resources include manganese, gold, ferberite, coal, barite, bentonite, uranium, and vanadium. Engineered barriers include bentonite clay and cement. Litter clumps were first developed by using calcium bentonite clay. A mining industry utilising rich deposits of bentonite clay is developing. The most common bleaching agent employed is bleaching earth, a type of bentonite clay. Experts debate a number of nomenclatorial problems with the classification of bentonite clays. A small amount of bentonite is often added to make a clay mixture more plastic. Space around the canisters will be filled with bentonite clay. Granular bentonite is being studied for use in battlefield wound dressings. Other industries include mineral extraction (bentonite) and tourism. This shale is classified as a firm shale and contains thin (< layers of bentonite. For industrial purposes, two main classes of bentonite exist&colon; sodium and calcium bentonite. The island has layers of Kaolinite and Bentonite which used to be mined. Coal beds, bentonite and coquinas are also observed.