Occurrence of SiC and Diamond Polytypes, Chromite and Uranophane in Breccia from Nickel Laterites (New Caledonia): Combined Analyses

Different techniques have been combined to identify the structure and chemical composition of siliceous breccia from a drill core nickel laterites in New Caledonia (Tiebaghi mine). XRD analyses show quartz as major phase. Micro-Raman spectroscopy confirmed presence reddish microcrystalline phase with inclusion microparticles iron oxides oxyhydroxide. Lithoclasts present are composed lizardite, chrysotile, forsterite, hedenbergite saponite. The veins cutting through filled Ni-bearing talc. Furthermore, for first time, we discovered diamond microcrystals accompanied by moissanite polytypes (SiC), chromite (FeCr2O4) uranophane crystals (Ca(UO2)2(SiO3OH)2.5(H2O)) lonsdaleite (2H-[C-C]) porosities breccia. origin SiC attributed ultrahigh-pressure crystallization lower mantle. inherited serpentinized peridotites having experienced interaction boninitic melt. Serpentinization, then weathering into saprolite, did not affect resistant polytypes, lonsdaleite. During karstification brecciation, silica rich aqueous solutions partly digested saprolite. Again, polymorph represent stable relicts this dissolution process being deposited pores. Uranophane is neoformed crystallized solutions. Our study highlights need combining mineralogical analytical technologies acquire most comprehensive information on samples, well value Raman characterizing structural properties porous materials.