Word to the wise

Abstract

G angue (pronounced gang) is the term used to collectively describe the valueless minerals in an ore deposit. This view of gangue equates value with ore minerals. The table gives the most common gangue minerals (Rimstidt 1997). As one reads through this list, however, it becomes obvious that many gangue minerals may be of great value in the mineral-specimen market. Also, inclusion in the table does not preclude a mineral from being economically important in some deposits; it only indicates that it is commonly found in uneconomic concentrations associated with other minerals that are ores. For example, fluorite (our major source of fluorine) is a primary ore mineral in many deposits, such as the manto fluorite deposits of the Buenavista-Encantada and El Tule mining districts, northern Coahuila, Mexico (Temple and Grogan 1963; Rakovan 2003), but it is a common gangue mineral in most Mississippi Valley-type (MVT) lead-zinc deposits (Misra 1999). An important exception to this last example are anomalously fluorite-rich MVTs such as those found in the Kentucky-Illinois fluorite district (once the world's largest source of fluorite ore; Park and MacDiarmid 1975).