Geological, Geochemical and Mineralogical Characteristics of the Asturias Fluorspar District, Northern Spain

Exploration & Mining Geology, Vol. 3, No. 1, 1994

JESUS GARCIA IGLESIAS and JORGE LOREDO, Departamento de Explotacion y Prospeccion de Minas, Escuela de Minas, Universidad de Oviedo, Oviedo, Espana

The Asturian fluorspar district consists of vein and stratiform deposits where mineralization is controlled by a combination of lithologjcal and tectonic factors. It is postulated that these fluorspar deposits have been formed under disequilibrium conditions created during circulation of ascending hydrothermal solutions along faults and other high permeability conduits. Mixing of solutions is inferred from fluid inclusion studies. Cavity filling and replacement processes are very important in localizing the ore deposits and in determining their morphology. Permian volcanic rocks in the area yield a regional positive geochemical anomaly in fluorine implying that Permian vulcanism may be a possible primary source of fluorine. On a regional scale a relationship can be established between some of the ore deposits and important tectonic lineaments. The stratiform deposits preferentially occur within a calcareous-detrital fades located at the margins of basins. These basin margins are related to important synsedimentary faults. Fluorite is the only economic mineral in these deposits. Quartz, carbonates, barite and pyrite are common minerals accompanying fluorite. Other minerals that may occasionally be present as minor components are: marcasite, chalcopyrite, fahlore, sphalerite, galena and related supergene minerals.