TY - JOUR
T1 - Marshallsussmanite, NaCaMnSi 3 O 8 (OH), a new pectolite-group mineral providing insight into hydrogen bonding in pyroxenoids
AU - Origlieri, Marcus J.
AU - Downs, Robert T
AU - Hoffman, Derek R.
AU - Ducea, Mihai N.
AU - Post, Jeffrey E.
N1 - Funding Information:
The authors would like to thank Michael Scott and Science Foundation Arizona for support of the RRUFF project. Thanks also to Dan and Diana Weinrich, Jeff Scovil and John Veevaert, who provided specimen details and photography. Careful readings by Charles Prewitt and Bob Hazen improved the manuscript. Thanks to Uwe Kolitsch for pointing out an additional occurrence. Thanks to László Horváth for pointing out a further occurrence and the loss of the accent mark for serandite. Bruce Cairncross provided much insight on the mineral occurrences at Wessels. The writer acknowledges computer support from Stephen G. West. Author M.N.D. acknowledges support from the Romanian Executive Agency for Higher Education, Research, Development and Innovation Funding project PN-III-P4-ID-PCCF-2016-0014.
Publisher Copyright:
Copyright © The Author(s), 2018. Published by Cambridge University Press on behalf of The Mineralogical Society of Great Britain and Ireland.
PY - 2021/6
Y1 - 2021/6
N2 - Marshallsussmanite (IMA2013-067) is a new pyroxenoid mineral from the Wessels mine, Kalahari Manganese Field, Northern Cape Province, South Africa. Marshallsussmanite has ideal formula NaCaMnSi3O8(OH) and triclinic P symmetry. Marshallsussmanite forms vitreous pink bladed crystals to 2.1 cm. The mineral shows perfect cleavage on both {100} and {001}. The chemical composition from electron microprobe (average of 20 analyses) and inductively coupled plasma mass spectrometer analysis (average of three analyses) is Li2O 0.43, Na2O 8.06, MgO 0.08, CaO 15.33, MnO 21.79, SiO2 51.71; totalling 97.40 wt.%. The empirical formula, normalized to 3 Si and assuming 1 H apfu is Li0.100Na0.906Ca0.953Mg0.007Mn1.071Si3O8(OH). Unit-cell parameters from single crystal X-ray diffraction are a = 7.7854(4), b = 6.9374(4), c = 6.8516(3) Å, α = 90.683(3)°, β = 94.330(3)°, γ = 102.856(3)°, V = 359.59(3) Å3; Z = 2. The crystal structure refinement converged with Robs = 0.0248 and site occupancy refinement gives crystal chemistry [Na0.948Li0.052][Ca0.793Mn0.207] [Mn0.937Ca0.063]Si3O8(OH). Marshallsussmanite is a single chain silicate with a repeat interval of three tetrahedra (i.e. dreier chain). Marshallsussmanite is a member of the pectolite group of pyroxenoids, which also includes barrydawsonite-(Y), cascandite, pectolite, serandite and tanohataite. Parallel silicate chains form layers, intercalated with well-ordered cation layers. Calcium and Mn both exhibit octahedral coordination, while Na has four bonded interactions in a coordination sphere (radius 3 Å) of seven separate O atoms. Procrystal electron density and bond valence modelling results are compared. The mineral has an unusually strong hydrogen bond with O4O3 separation of 2.458(2) Å. Unlike pectolite and serandite, O4 in marshallsussmanite acts as an H-bond donor and O3 is an H-bond acceptor. Cation ordering in pyroxenoids has a substantial impact on the H position and corresponding H-bonding schemata.
AB - Marshallsussmanite (IMA2013-067) is a new pyroxenoid mineral from the Wessels mine, Kalahari Manganese Field, Northern Cape Province, South Africa. Marshallsussmanite has ideal formula NaCaMnSi3O8(OH) and triclinic P symmetry. Marshallsussmanite forms vitreous pink bladed crystals to 2.1 cm. The mineral shows perfect cleavage on both {100} and {001}. The chemical composition from electron microprobe (average of 20 analyses) and inductively coupled plasma mass spectrometer analysis (average of three analyses) is Li2O 0.43, Na2O 8.06, MgO 0.08, CaO 15.33, MnO 21.79, SiO2 51.71; totalling 97.40 wt.%. The empirical formula, normalized to 3 Si and assuming 1 H apfu is Li0.100Na0.906Ca0.953Mg0.007Mn1.071Si3O8(OH). Unit-cell parameters from single crystal X-ray diffraction are a = 7.7854(4), b = 6.9374(4), c = 6.8516(3) Å, α = 90.683(3)°, β = 94.330(3)°, γ = 102.856(3)°, V = 359.59(3) Å3; Z = 2. The crystal structure refinement converged with Robs = 0.0248 and site occupancy refinement gives crystal chemistry [Na0.948Li0.052][Ca0.793Mn0.207] [Mn0.937Ca0.063]Si3O8(OH). Marshallsussmanite is a single chain silicate with a repeat interval of three tetrahedra (i.e. dreier chain). Marshallsussmanite is a member of the pectolite group of pyroxenoids, which also includes barrydawsonite-(Y), cascandite, pectolite, serandite and tanohataite. Parallel silicate chains form layers, intercalated with well-ordered cation layers. Calcium and Mn both exhibit octahedral coordination, while Na has four bonded interactions in a coordination sphere (radius 3 Å) of seven separate O atoms. Procrystal electron density and bond valence modelling results are compared. The mineral has an unusually strong hydrogen bond with O4O3 separation of 2.458(2) Å. Unlike pectolite and serandite, O4 in marshallsussmanite acts as an H-bond donor and O3 is an H-bond acceptor. Cation ordering in pyroxenoids has a substantial impact on the H position and corresponding H-bonding schemata.
KW - NaCaMnSi 3 O 8 (OH)
KW - Raman spectroscopy
KW - bond valence
KW - chain silicate
KW - hydrogen bond
KW - marshallsussmanite
KW - pectolite
KW - pectolite group
KW - procrystal electron density
KW - pyroxenoid
KW - single-crystal X-ray diffraction
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U2 - 10.1180/mgm.2018.2
DO - 10.1180/mgm.2018.2
M3 - Article
AN - SCOPUS:85109218879
VL - 85
SP - 444
EP - 453
JO - Mineralogical Magazine
JF - Mineralogical Magazine
SN - 0026-461X
IS - 3
ER -