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Preliminary Analysis of an Ultrarefractory Material from Granada, Colorado, USA

Neil B. Ray and Timothy C. Mullin, Department of Geosciences, Fort Hays State University, Hays, Kansas, 67601; nbray@scatcat.fhsu.edu, t_mullin@scatcat.fhsu.edu

 

ABSTRACT

An unusual material having a recoverable mass of 3.5 kg was found by an anonymous finder in a field near Granada, Colorado, USA. The Granada specimen is an ultrarefractory material composed of 26.15% SiO2, 39.36% CaO, 18.32% FeO* (reported as both FeO and Fe2O3), 5.63% MgO, and 5.38% MnO. Selected important trace element chemistry analysis values are (ppm): As (9.0), Cu (113.0), Rb (14.0), Sm (1.6), Sr (180.0), Th (3.5), and U (1.9). Electron microprobe (EMP) analysis indicates that the material is composed of 14 different mineral phases, dominated by: larnite, merwinite, sadanagaite, ilmenite, magnesiowustite, and spinel (high-manganese?). The mineral composition approaches that of a calcium aluminum inclusion (CAI), which is found in chondrites; whereas the chemical composition resembles that of an industrial material, steel slag.

18O and 17O isotope values are 14.10 and 7.20, respectively, where D17O has a deviation of -0.06. The origin of the unusually high oxygen isotope values are unknown, for they may reflect a primitive meteorite composition. Very near infrared spectroscopy (VNIR) was conducted on the specimen. Though inconclusive, the VNIR analysis of the material resembles a spectral reflectance to a class G asteroid, particularly Ceres. Analysis of this material indicates a possible extraterrestrial origin with some properties similar to terrestrial rocks. Future research involving solar-wind component (4He/20Ne), aluminum isotopes (26Al), and U/Pb radiometric data are necessary before drawing final conclusions.