Cyprine, ideally Ca19Cu2+(Al,Mg,Mn)12Si18O69(OH)9, was found at the Wessels mine near Hotazel, Kalahari Manganese Field, North Cape province, South Africa. It occurs as chaotic aggregates (up to 5 cm across) in open cavities or embedded in coarse-grained colourless calcite. Associated minerals are calcite, apatite, andradite, henritermierite and rhodochrosite. Single crystals of cyprine up to 1 cm are dark red with a lilac hue and vitreous lustre. Dominant crystal forms are {1 0 0}, {1 1 0} and {3 3 1}. The Mohs hardness is 6.5. Dmeas and Dcalc are 3.40(3) and 3.41 g/cm3, respectively. Cyprine is optically uniaxial, negative, ω = 1.744(2), ε= 1.732(2) (in white light). Pleochroism is strong; ranging from O = dark purple, E = pale red to O = dark reddish brown, E = pale yellowish brown; OE. Chemical composition (electron microprobe, H2O by thermogravimetric analysis (TGA)) of two chemically different zones (zone-1/zone-2, wt.%) is: SiO2 36.98/36.51; Al2O3 14.98/13.70; CaO 36.70/36.18; MgO 3.24/1.10; Mn2O3 2.27/6.04; CuO 2.39/1.86; Fe2O3 0.62/2.50; Cr2O3 0.23/0.04; H2O 3.30/3.30, total 100.71/101.23. The crystal-chemical formulae (based on the FTIR, TGA/differential scanning calorimetry, SREF, WDS and optical spectra) are Ca8.00Ca1.00(Cu0.95Mg0.05)Ʃ1.00Al4.00(Al5.50Mg1.00Mn3+1.19Fe3+0.22Cr0.09)Ʃ8.00([SiO4]9.91[H4O4]0.09)Ʃ10.00[Si2O7]4((OH)9O)9.91 and Ca18.00Ca1.00(Cu0.90Mg0.10)Ʃ1.00(Al3.22Mn3+0.60Fe30.18)Ʃ4.00(Al4.72Mn3+1.20Fe3+1.06Mn2+0.60Mg0.40Cr0.02)Ʃ8.00([SiO4]9.91[H4O4]0.09)Ʃ10.00[Si2O7]4((OH)9O)Ʃ10.00 for zone-1 and zone-2, respectively. Absorption bands in the IR spectrum are 443, 490, 574, 604, 671, 814, 905, 972, 1015, 3354, 3640 cm−1. The polarized optical absorption spectra have two strong absorption bands at 415 and 555 nm and a less intense band at 645 nm. The eight strongest lines of the powder X-ray diffraction pattern are (I–d(Å)–h k l): 12–5.89–002, 12–3.007–431, 47–2.950–004, 100–2.75–432, 76–2.594–522, 35–2.459–620, 10–2.324–144, 28–1.6224–672. Cyprine is tetragonal, space group P4/n, unit-cell parameters refined from the powder data are a = 15.5652(5), c = 11.7921(4), V = 2863.2 (2) Å3,Z = 2. The crystal structure has been refined to R1 = 0.034 and R1 = 0.035 for 2848 and 2071 unique observed reflections with |Fo| ≥ 4σF for the zones 1 and 2, respectively. The structure refinements provide scattering factors of the Y1A,B sites close to 29 e, which supports occupancy of these sites by Cu2+ ions. The copper coordination polyhedra possess strong Jahn–Teller distortion: Y1A–O6(4×) = 2.043(3) Å and Y1A–O10 = 2.258(6) Å for zone-1 and Y1B–O6(4×) = 2.010(4) Å and Y1B–O10 = 2.274(7) Å for zone-2. Cyprine is defined as a member of the vesuvianite group with Cu2+ as a dominant cation in the Y1 site. The historical name cyprine (derived from Latin cuprum, copper) given by J.J. Berzelius in 1821 for Cu-bearing vesuvianite is transferred to the new mineral.

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