NORMANDITE, THE TI-ANALOG OF LAVENITE FROM MONT-SAINT-HILAIRE, QUEBEC

Normandite, the titanium analogue of lavenite, is a new mineral specie s from the Poudrette quarry Mont Saint-Hilaire, Quebec. It is found in nepheline syenite and in miarolitic cavities in nepheline syenite, as sociated with nepheline, albite, microcline, aegirine, natrolite, cata pleiite, kupletskite, eudialyte, cancrinite, villiaumite, rinkite and donnayite-(Y). It occurs as transparent to translucent orange-brown ag gregates of subparallel acicular crystals up to 10 mm in length, and a s patches of yellow, fibrous crystals. It has a white to very pale yel low streak and vitreous luster. It is brittle, with distinct {100} and {001} cleavages, and a conchoidal fracture. Normandite is biaxial neg ative, with indices of refraction alpha 1.743(2), beta 1.785(2) and ga mma 1.810(5), 2V(meas) in the range 72-84 degrees, 2V(calc). = 74 degr ees and a moderate dispersion r>v. Pleochroism is pronounced: X pale y ellow, Y yellow, Z brownish red to deep red. The optical orientation i s Y = b, X boolean AND c = 15 degrees (in obtuse angle beta). Normandi te is monoclinic, space group P2(1)/a, with a 10.828(7), b 9.790(7), c 7.054(2) Angstrom, beta 108.20(3)degrees, V 709.9(8) Angstrom(3) and Z = 4. The strongest six lines of the X-ray powder-diffraction pattern [d in Angstrom(I)(hkl)] are: 3.942(20)((1) over bar 21), 3.234(30)(31 0), 2.859(100)(1) over bar 12), 2.807(70)(320), 1.762(20)((2) over bar 04) and 1.741(20)(242). The crystals are elongate on [001] and flatte ned on {010}, with the following forms, in order of predominance: {100 }, {110} and {001}. Electron-microprobe analyses gave Na2O 9.26(9.19-9 .40), K2O 0.01(0.01-0.02), CaO 15.38(15.08-15.59), MnO 9.31(9.11-9.52) , FeO 6.13(5.89-6.26), TiO2 17.51(17.09-17.83). Nb2O5 3.89(3.51-4.61), ZrO2 2.62(2.29-2.73), SiO2 31.92(31.69-32.04), F 5.11(4.82-5.31), O = F -2.15, total 98.99 wt.%. The empirical formula based on 9(O + F) is : Na1.12Ca1.03(Mn0.49Fe0.32)(Sigma 0.81)(Ti0.82Nb0.11Zr0.08)(Sigma 1.0 1)Si2.00O7.99F1.01, ideally NaCa(Mn,Fe)(Ti,Nb,Zr)Si2O7OF; D-meas = 3.5 0(1),D-calc. = 3.48 g/cm(3). The name honors Charles Normand, who disc overed the species.