RODOLICOITE AND GRATTAROLAITE, 2 NEW PHOSPHATE MINERALS FROM SANTA-BARBARA MINE, ITALY

Grattarolaite and rodolicoite, two new anhydrous iron phosphates, were found at Santa Barbara lignite mine as reddish-brown nodules. They oc cur as small crystallites (< 1000 Angstrom), associated in fine-scale intergrowth that prevent the measurement of physical properties. Gratt arolaite is trigonal, with space group R3m; rodolicoite is also trigon al, but with space group P3(1)21. Cell dimensions, calculated from X-r ay powder patterns, are: grattarolaite a = 7.994(4), c = 6.855(4) Angs trom, V = 379.4 Angstrom(3), Z = 3; rodolicoite a = 5.048(3), c = 11.2 15(8) Angstrom, V = 247.5 Angstrom(3), Z = 3. The chemical data, obtai ned by transmission electron microscope microanalysis, give the compos ition Fe2.99P1.01O7.00 for grattarolaite and Fe1.04P0.96O4.00 for rodo licoite. Infrared spectroscopy and thermal analysis confirm the anhydr ous nature of both minerals.