Trace elements in Peña Blanca Spring Oldhamite

Murrell and Burnett (M-B) ( 1982) reported that oldhamite (CaS) is the primary host phase of U and Th in the E6 chondrites. E-chondrite Th/U values were all cosmic, indicating a lack of Th-U fractionation in both oldhamite and in the bulk meteorites. In Khairpur (E6), they attributed excess fossil fission tracks to the presence of 244Pu in oldhamite. Rare earth (REE) enrichments were inferred for an Abee (E4) water soluble phase(s) (Frazier and Boyton, 1981), presumably oldhamite, and perhaps niningerite. These led M-B to suggest that the enstatite chondrites may be well-suited for Pu-U chronology and possibly for providing the initial Pu/U Value in the solar system