Estudo preliminar do depósito de paligorsquite de Figueiró do Campo (Soure, Portugal) Preliminary studies of the palygorskite deposit from Figueiró do Campo (Soure, Portugal)

The technical characteristics of miocenic palygorskite rich-sediments from an area near Figueiro do Campo (Soure, Portugal) are presented. The deposit is probably the most promising area in Portugal concerning palygorskite as a resource. In this first study we evaluate three samples collected in the bottom, medium and top levels of the deposit. The samples has 58-79 % in weight under 63 µ and the average particle size in the fraction < 63 µ has 0.2 to 2.2 µ in size. DRX data revealed that the fraction < 63 µ are 26-34 % quartz, 4-6 % Fe oxide and 61-70 % palygorskite. The fraction < 2 µ is 89-93 % palygorskite, 4-8 % quartz, 3-4 % Fe oxide and 0-3 % caolinite. The palygorskite fibbers were observed in MEV and average 344 nm (length) and 31 nm (thickness). From FRX analysis we obtain the following compositions: 69-60 % SiO 2 , 11-17 % Al 2 O 3 , 7.5-5.1 % MgO and 3.6-6.6 % Fe total. CTC are in the range 7.2-11.2 meq/100g, and the pH between 6.0