Cyprine, ideallyCa₁₉Cu²⁺(Al,Mg,Mn)12Si18O69(OH)9,was found at theWessels mine near Hotazel,KalahariManganese 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}, {11 0} and {3 3 1}. TheMohs hardness is 6.5.D_meas and D_calc are 3.40(3) and 3.41 g/cm³, respectively. Cyprine is optically uniaxial, negative, ω = 1.744(2), e = 1.732(2) (inwhite light). Pleochroism is strong; ranging from O= dark purple, E= pale red to O= dark reddish brown, E= pale yellowish brown; O>E. Chemical composition (electron microprobe, H₂O by thermogravimetric analysis (TGA)) of two chemically different zones (zone-1/zone-2, wt.%) is: SiO₂36.98/36.51; 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 Ca_18.00Ca_1.00(Cu_0.95Mg_0.05)Σ_1.00A_l4.00(Al_5.50Mg_1.00Mn³⁺ 1.19Fe³⁺ _0.22Cr_0.09)Σ_8.00([SiO₄]_9.91[H₄O₄]_0.09)Σ_10.00 [Si₂O₇]₄((OH)₉O)_Σ10.00 and Ca_18.00Ca_1.00(Cu_0.90Mg_0.10)_Σ1.00(A_l3.22Mn³⁺ _0.60Fe³⁺ _0.18)_Σ4.00(A_l4.72Mn³⁺ 1.20Fe³⁺ 1.06Mn₂+ _0.60Mg_0.40Cr_0.02) _S8.00([SiO₄]_9.91[H₄O₄]_0.09)_Σ10.00[Si₂O₇]4((OH)9O)_Σ10.00 for zone-1 and zone-2, respectively. Absorption bands in the IR spectrum are 443, 490, 574, 604, 671, 814, 905, 972, 1015, 3354, 3640cm^-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, 12-3.007-4 3 1, 47-2.950-004, 100-2.75-4 3 2, 76-2.594-522, 35-2.459-6 2 0, 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)ų,Z = 2.The crystal structure hasbeen refined toR1=0.034andR1 = 0.035for2848and2071unique observedreflectionswith |F_o|=4sF 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 byCu2+ 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.