Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF. The underground resources include gold, zinc, copper, fluorspar, limestone, granite, and kaolin. In 1833, David Brewster discovered the fluorescence of the mineral fluorite or fluorspar. The product was made by combining borax, cryolite, kaolinite, manganese, silica, feldspar, and fluorspar. Non-metal minerals include limestone, marble, fluorspar, silica, pearlite, bentonite etc. Other fluxes include dolomite, soda ash, and fluorspar. Most are engaged in the extraction of kaolin, fluorspar and Agalmatolite and Kaolin is exported. Historically the area has been mined for lead, silver, zinc, coal and fluorspar. Tajikistan also produces strontium, salt, lead, zinc, fluorspar, and mercury. Examples include fluorspar and potash, which are essentially confined to National Parks. Industrial mineral production in Namibia includes salt, fluorspar, wollastonite and dimension stone. The name later evolved into "fluorspar" (still commonly used) and then "fluorite". Among the Central Asian republics, Tajikistan ranks first in lead, zinc, and fluorspar resources. Other activities include small business, tourism and fluorspar mining in Kerio Valley. This activity may also have provided the fluorine in the fluorspar deposits in the region.