• journal_title：European Journal of Mineralogy
• Contributor：Frédéri HATERT ; Pierre LEFÉVRE ; André-Mathieu FRANSOLET ; Marie-Rose SPIRLET ; Leila REBBOUH ; François FONTAN ; Paul KELLER
• Publisher：E. Schweizerbart'sche Verlagsbuchhandlung Science Publishers
• Date：2005-
• Format：text/html
• Language：en
• Identifier：10.1127/0935-1221/2005/0017-0749
• journal_abbrev：Eur J Mineral
• issn：0935-1221
• volume：17
• issue：5
• firstpage：749
• section：Articles

Ferrorosemaryite, ideally □ NaFe²⁺Fe³⁺Al(PO₄)₃, is a new mineral species from the Rubindi pegmatite, Rwanda. It occurs as large idiomorphic grains reaching 3 mm, embedded in scorzalite. Associated phosphate minerals are scorzalite, trolleite, montebrasite, bertossaite, brazilianite, with accessory augelite, triplite and lacroixite. The mineral is transparent and exhibits a dark-green to bronze colour, with a resinous lustre and with a greenish to brownish streak. It is non-fluorescent, brittle, and shows a perfect {010} cleavage and a good {1̄01} cleavage. The estimated Mohs hardness is 4. The calculated density is 3.62 g/cm³. Ferrorosemaryite is biaxial negative, with α = 1.730(5), β = 1.758(7), and γ= 1.775(5) (Λ = 590 nm). Pleochroism is from dark green (X) to dark brown (Z). The measured 2V angle is 82(1)°, and the calculated 2V angle is 75°. A strong dispersion r < v has been observed, but the optical orientation has not been determined. Electron microprobe analyses gave P₂O₅ 46.00, Al₂O₃ 9.12, Fe₂O₃ 21.01, FeO 11.10, MgO 0.19, MnO 7.96, CaO 0.44, Na₂O 2.85, K₂O 0.01, total 98.68 wt. %. The resulting empirical formula, calculated on the basis of 12 O, is □_1.00(Na_0.42Mn²⁺_0.28Ca_0.04□_0.26)Σ_1.00(Fe²⁺_0.71Mn²⁺_0.24Fe³⁺_0.05)Σ_1.00Fe³⁺_1.00(Al_0.82Fe³⁺_0.16Mg_0.02)Σ_1.00[(P_0.99□_0.01)O₄]₃. The single-crystal unit-cell parameters are a = 11.838(1), b = 12.347(1), c = 6.2973(6) Å, β = 114.353(6)°, and V = 838.5(1) ų, space group P2_1/n. The eight strongest lines in the powder X-ray diffraction pattern [d(in Å)(I)(hkl)] are: 8.102(30)(110), 6.167(50)(020), 5.382(40)(200), 4.054(45)(220), 3.448(65)(310), 3.011(40)(112̄), 2.693(75)(400), 2.677(100)(240). Ferrorosemaryite is the Fe²⁺ analogue of rosemaryite, and belongs to the wyllieite group of minerals. The crystal structure of ferrorosemaryite has been refined, based on single-crystal X-ray diffraction data, to R₁ = 2.43 %. The infrared spectrum is similar to those of alluaudite-type phosphates. The mineral species and name were approved by the Commission on New Minerals and Mineral Names of the International Mineralogical Association (no. 2003–063).