Major fluorspar districts are localized chiefly along and near continental rift zones and lineaments. More than 45 districts are cited along the Rio Grande graben of New Mexico and Colorado and along this rift projected northward through Colorado, Wyoming, Idaho, Montana, British Columbia, Yukon Territory, and Alaska and projected southward into Mexico. Other fluorspar districts similarly are associated with tensional rifts and lineaments in Illinois, Kentucky, Oregon, Nevada, Ontario, Nova Scotia, Newfoundland, Germany, France, Sardinia, U.S.S.R., India, Kenya, Tanzania, Malawi, and Mozambique. Evidently large volumes of fluorine leaked upward from the lower crust or mantle along and near the rifts.This association of major fluorspar districts and continental rifts and lineaments is regarded as a regional guide in the search for new fluorspar districts. The fluorspar may be accompanied by commercial quantities of barite, zinc, lead, molybdenum, uranium, thorium, niobium, tin, beryllium, or rare-earth minerals.