Rodolicoite and grattarolaite, two new phosphate minerals from Santa Barbara Mine, Italy
Cipriani, Curzio; Mellini, Marcello; Pratesi, Giovanni; Viti, Cecilia
European Journal of Mineralogy Volume 9 Number 5 (1997), p. 1101 - 1106
published: Sep 24, 1997
manuscript accepted: Apr 1, 1997
manuscript received: Mar 18, 1996
ArtNo. ESP147050905016, Price: 29.00 €
Abstract Grattarolaite and rodolicoite, two new anhydrous iron phosphates, were found at Santa Barbara lignite mine as reddish-brown nodules. They occur as small crystallites (< 1000 Å), associated in fine-scale intergrowth that prevent the measurement of physical properties. Grattarolaite is trigonal, with space group R3m; rodolicoite is also trigonal, but with space group P3 j 21. Cell dimensions, calculated from X-ray powder patterns, are: grattarolaite a = 7.994(4), c = 6.855(4) Å, V = 379.4 Å3, Z= 3; rodolicoite a = 5.048(3), c = 11.215(8) Å, V= 247.5 Å3, Z= 3. The chemical data, obtained by transmission electron microscope microanalysis, give the composition Fe2.99P1.01O7.00 for grattarolaite and Fe2.99P1.01O7.00 for rodolicoite. Infrared spectroscopy and thermal analysis confirm the anhydrous nature of both minerals.