FIELD TRIP GUIDE TO THE SERIDÓ PEGMATITE PROVINCE

The pegmatites of the Seridó Pegmatite Province show a granitic bulk mineralogical composition, composed K-feldspar, albite, quartz, muscovite and occasionally biotite. Detailed studies major minerals are scarce. There is, on other hand, relatively larger number published contributions concerning pegmatite accessory minerals. This field trip guide focus mainly occurrence locations these last minerals, which group here by their most frequently recovered rare metals gems: (1) Ta-Nb: Tantalite-columbite is main mineral group, even though varieties may be as microlite, tapiolite, strueverite, simpsonite, ixiolite, among others. Their grain size varies from centimeter to decimeter scale. mineralization disseminated (less frequently), in pockets, or aggregates crystals, usually associated with "replacement bodies" at contact between Zone III quartz core. They also occur sporadically II homogeneous pegmatites, crystals subcentimeter scale, quartz-feldspar-muscovite groundmass. In this case, they display lamellar habit normally lower Ta concentration. (2) Be: Beryl Be-mineral present. Its meter, it prismatic shows diverse colors (white, green, blue, pink, yellow), green white prevailing. It occurs Zones II, IV (quartz core), well association bodies". centimetric Some pseudoconical forms observed, contain inclusions. gem (aquamarine, morganite, heliodor) Ta-Nb ores exploited pegmatites. (3) Li: Li-minerals spodumene, lepidolite amblygonite. spodumene prevails over amblygonite lepidolite, although reserves Li still not completely known. Spodumene individual meter dimensions, rarely forming individualized zones. Lepidolite albitized deep blue tourmalines (named Paraíba Tourmaline). Amblygonite pockets width phosphates such lithiophilite, triphylite, siclerite, tavoríte, (4) Sn: Cassiterite Sn-ore, Sn present crystallographic structure found I heterogeneous some Cu (e.g. djurleite), U uraninite) REE xenotime) considered important resources exploted potential for further exploration.