ISBN:

Keywords:

Abstract:

Nolzeite, Na(Mn,) (sub 2) [Si (sub 3) (B,Si)O (sub 9) (OH) (sub 2) ].2H (sub 2) O, is a new mineral found in altered sodalite syenite at the Poudrette quarry, La Vallee-du-Richelieu, Monteregie (formerly Rouville County), Quebec, Canada. Crystals are colourless to pale green and are acicular with average dimensions of 5 mu m X 8 mu m X 55 mu m. They occur as radiating to loose, randomly oriented groupings within vugs associated with aegirine, nepheline, sodalite, eudialyte-group minerals, analcime, natron, pyrrhotite, catapleiite, steedeite and the unidentified mineral, UK80. Nolzeite is non-pleochroic, biaxial, with n (sub min) = 1.616(2) and n (sub max) = 1.636(2) and has a positive elongation. The average of six chemical analyses gave the empirical formula: Na (sub 1.04) (Mn (sub 1.69) (sub 0.24) Fe (sub 0.05) Ca (sub 0.02) ) (sub Sigma =2.00) (Si (sub 2.96 ) S (sub 0.04) ) (sub Sigma =3.00) (B (sub 0.70) Si (sub 0.30) ) (sub Sigma =1.00) O (sub 9) (OH) (sub 2) .2H (sub 2) O based on 13 anions. The Raman spectrum shows six distinct bands occurring at approximately 3600-3300 cm (super -1) and 1600-1500 cm (super -1) (O-H and H-O-H bending), 1300-1200 cm (super -1) (B-OH bending), 1030-800 cm (super -1) (Si-O-Si stretching) as well as 700-500 cm (super -1) and 400-50 cm (super -1) (Mn-O and Na-O bonding, respectively). The FTIR spectrum for nolzeite shows bands at approximately 2800-3600 cm (super -1) (O-H) stretching, a moderately sharp band at 1631 cm (super -1) (H-O-H) bending, strong, sharp bands at approximately 650-700 cm (super -1) , approximately 800-840 cm (super -1) , and approximately 900-1100 cm (super -1) (Si-O and B-O) bonds. Nolzeite is triclinic, crystallizing in space group P with a = 6.894(1), b = 7.632(2), c = 11.017(2) A, alpha = 108.39(3), beta = 99.03, gamma = 103.05(3) degrees , V = 519.27 A (super 3) , and Z = 2. The crystal structure was refined to R = 12.37% and wR (super 2) = 31.07% for 1361 reflections (F (sub o) > 4sigma F (sub o) ). It is based on chains of tetrahedra with a periodicity of three (i.e. a dreier chain) consisting of three symmetrically independent SiO (sub 4) tetrahedra forming C-shaped clusters closed by BO (sub 2) (OH) (sub 2) tetrahedra, producing single loop-branched dreier borosilicate chains. The chains are linked through shared corners to double chains of edge-sharing MnO (sub 5) (OH) octahedra. Nolzeite is a chain silicate closely related to steedeite and members of the serandite-pectolite series. Paragenetically, nolzeite is late-stage, probably forming under alkaline conditions and over a narrow range of low pressures and temperatures.

Notes:

GeoRef, Copyright 2018, American Geological Institute.<br/>2017-048011<br/>catapleiite<br/>La Vallee-du-Richelieu Quebec<br/>natron<br/>nolzeite<br/>Poudrette Quarry<br/>pyroxenoids<br/>serandite<br/>sodalite syenite<br/>steedeite