FERRI-CLINOHOLMQUISTITE, LI-2(FE2-B CLINOAMPHIBOLE FROM THE PEDRIZA MASSIF, SIERRA-DE-GUADARRAMA, SPANISH CENTRAL SYSTEM(,MG)(3)FE23+SI8O22(OH)(2), A NEW LI)

Ferri-clinoholmquistite is a new amphibole species from episyenites in the East Pedriza Massif (Central System, Spain), where it is associat ed to albite, augite-aegirine, titanite, andradite, magnetite, and apa tite. It is black, vitreous, translucent, non-fluorescent, and brittle . It shows gray streak, H(Mohs) = 6, splintery fracture, perfect {110} cleavage, (001) parting, D-meas = 3.19, and D-cal = 3.25. Crystals ar e prismatic, elongated on [001]. In plane-polarized light, it is stron gly pleochroic: X = yellow green, Y = indigo blue, Z = green blue, wit h absorption X < Y less than or equal to Z; Z = b, Y - c = 10(2)degree s, X - a similar to -2 degrees (in beta obtuse). Ferri-clinoholmquisti te is biaxial positive, alpha = 1.699(2), beta = 1.703(2), gamma = 1.7 08(2), 2V(z)(meas) = 72(7), 2V(z)(calc) = 84(6), r < nu. It is monocli nic, space group C2/ m, a = 9.472(4), b = 17.844(6), c = 5.276(6) Angs trom, beta = 101.97(9)degrees, V = 872(1) Angstrom(3), Z = 2. X-ray po wder-diffraction pattern data were determined. Analysis by a combinati on of electron microprobe and flame photometry gives the following for mula, calculated assuming OH + F = 2 and T sites fully occupied by Si: Na0.43K0.03)(B)(Li1.66Na0.30Ca0.04)(C)(Fe-1.54(3+) Fe1.352+Mg1.21Li0. 49Al0.20Ti0.124+ Mn-0.07(2+) Zn-0.02)(T)(Si-8)O-22 (OH1.58F0.42). From crystallographic refinements the M4 site is split, implying ordering of Li and Na, and within the A cavity, Na occupies the Am position.