Mineralogical characteristics of bulk deposition have been determined at seven sites along an altitudinal gradient in the southern face of Filabres Range from 1770 m altitude to sea level, over a period of 8 months, the rainiest in this semiarid area. X ray diffraction and scanning electron microscopy were used for identifying and semiquantifying minerals. The aim was twofold: to ascertain the contribution of mineral particles to both the high pH and alkalinity of bulk deposition, the highest in Europe, and to use mineralogy of bulk deposition as a possible fingerprinting technique to identify the source of insoluble particles. The pH, alkalinity, and electrical conductivity of rainwater increase down the altitudinal gradient as precipitation decreases, indicating a clear increase in alkaline particles, in agreement with the presence of calcite, aragonite, dolomite, and gypsum, which also explains high pH and alkalinity of the bulk deposition. Moreover, pH and conductivity of rainwater are somewhat more related to E--SE winds than to W--NW ones. In addition to carbonates and gypsum, seven silicate minerals were found. Some minerals like feldspars, chlorite, and aragonite, are neither related to site nor to rain events. Some others, like quartz, high-crystalline illite, paragonite, and kaolinite, are only related to rain events. Finally, a few minerals, like low-crystalline illite, palygorskite, paragonite, and to some extent calcite and gypsum, are site related. Some minerals have been interpreted to come from local sources, e.g., high-crystalline illite, gypsum, and paragonite; others, like palygorskite and low-crystalline illite, smaller in size, may come from distant sources. ¿ American Geophysical Union 1993