Occurrence of Spurrite-Tilleyite-Rustumite-Hillebrandite

Rare High-temperature and low-pressure contact-metamorphic assemblages have been found in the Güneyce-Ikizdere area, Eastern Black Sea, Turkey (Pontides), well-known for the kuroko-type massive sulfide deposits (e.g., Çayeli, Murgul, Cerrattepe). Plutonic rocks of calc-alkaline affinity (Rize batholith) intrude Cretaceous volcanic and volcano-sedimentary formations. An unusual contact metamorphism resulted in the development of assemblages belonging to the spurrite-merwinite facies at the contact between a cupola of the Rize batholith and lower Cretaceous limestone. The following rare calc-silicate minerals, mostly forming monomineralic masses, have been identified: spurrite Ca5(SiO4)2(CO3), tilleyite Ca5Si2O7(CO3)2, rustumite Ca10(Si2O7)2SiO4Cl2(OH)2, cuspidine Ca4Si2O7(F,OH)2, hillebrandite Ca2SiO3(OH)2, killalaite Ca3Si2O7.H2O, foshagite Ca4Si3O9(OH)2, gehlenite Ca2Al(AlSi)O7, monticellite CaMgSiO4, dellaite Ca6Si3O11(OH)2, bicchulite Ca2Al2SiO6(OH)2, tobermorite Ca9Si12O30(OH)6.4H2O, perovskite CaTiO3, thaumasite Ca6Si2(CO3)2 (SO4) (OH)12.24H2O and hydroxylellestadite-(OH) Ca5(SiO4,SO4,PO4)3 (OH,F,Cl,CO3).