Extraterrestrisk och terrestrisk kromrik spinell i fanerozoiska kondenserade sediment
… with known sedimentation rate in Zumaia, northern Spain, 90,5 kilogram of condensed limestone, dated to about 63 Ma, was sampled. The limestone was dissolved in hydrochloric- and hydrofluoric acid and the residue was sieved and searched for opaque minerals under the binocular …