R chondrites are among the most oxidized chondrite groups; they also have the highest Δ¹⁷O values known in whole-rock meteorites. We analyzed R chondrites (six Antarctic, four hot-desert) by instrumental neutron-activation analysis. Data for one of the former and three of the latter show large weathering effects, but the remainder show only moderate scatter and permit us to determine trends and mean compositions for the group. Bulk R-chondrite compositions are similar to those in H and L chondrites, but the concentrations of several volatiles, especially Se and Zn, are higher; the more volatile the element, the higher the enrichment in R chondrites relative to H and L.
Petrologic types in R chondrites extend as low as 3.6. We determined olivine compositional distributions and studied opaque oxides in 15 R-chondrite thin sections, including a newly discovered R4 clast in Bencubbin (adding to the diversity of chondritic clasts in this polymict breccia) and an R clast in CM2 Murchison. Opaque oxides in R chondrites include nearly pure magnetite, Al-rich chromite, magnetite-chromite solid solution, nearly pure chromite, and ilmenite. This diverse set of opaque phases reflects differing aqueous-alteration conditions.
The least equilibrated R chondrites contain nearly pure magnetite but the spinels in metamorphosed R chondrites contain additional components (e.g., Cr₂O₃ and Al₂O₃ and some minor cations). The NiO content in olivine correlates with the magnetite component in magnetite-chromite solid solution in equilibrated R chondrites and is a function of the degree of oxidation. The absence of metallic Fe in A-881988 and LAP 031156 indicates a high degree of oxidation; the relatively low-FeO (Fa35) olivine in these rocks in part reflects the conversion of Fe²⁺ to Fe³⁺ and its partitioning into magnetite. Oxidation trends in R chondrites are affected by both aqueous alteration and thermal metamorphism. The differing degrees of oxidation in this group reflect differences in local environments on the parent asteroid.

The Aristarchus region of Oceanus Procellarum is an area concentrated with lunar basalts, which were mainly produced by the last major phase of lunar volcanism on the western nearside. A group of lunar sample and remote sensing scientists have carried out the extensive task of characterization of lunar mare soils with regard to their mineralogical and chemical makeup and regional geologic mapping. Spectral parameters of the high spatial resolution Clementine images are used to identify and define these basalts as different compositional and spectral units. This endeavor is aimed at deciphering the subtle spectral characteristics of mare soils and validating the mapping technique used in this study, together with making statistical analysis of the links between the basalt types with ages in order to provide a further understanding of material types and geologic evolution in the Aristarchus region of the Moon. From the new perspective of mining geologic information in multivariable image-spaces, spectrally distinct 9 high-Ti and 11 low-Ti basalt reference spectra have been distinguished and as a result, more than 70 spectrally and compositionally basaltic units, which range in age from 1.20 b.y. to 3.74 b.y., have been identified. To some extent, a potential relationship between composition and relative age exists in the statistical analysis of the links between spectral types (related with the Clementine ratio colors) of various basalts and ages in this study, which suggests that composition with different states of maturity correlate with age to some extent. The mineralogical characteristics and spectra-age relationship in the Marius Hills region indicate that the early basalts may still be exposed at the surface deposit after prolonged volcanic activity in this region. This may be a result of not being blanketed by later lava flows, or lava extrusions of underlying low-Ti basalts. In addition, stratigraphic analysis also reveals and confirms that TiO₂ concentrations appear to vary independently with time, and generally eruptions of TiO₂-rich and TiO₂-poor basalts have occurred contemporaneously.

We report the discovery of a planetary nebula centered on the poorly studied symbiotic binary star DT Ser. In a few other symbiotic stars spatially resolved nebulae have been discovered as well, but only one of them probably is a genuine planetary nebula, while the others are likely to originate in complex mass-ejection episodes from the interacting binary central stars that are possibly related to nova-like outbursts. The rim of the planetary nebula around DT Ser is severely distorted toward a brighter star 5 arcsec away. In infrared WISE data, this star shows the presence of a detached cold-dust shell similar to those observed in post-AGB stars. The apparent association of the symbiotic star and its planetary nebula with the nearby possible post-AGB object is discussed. We also discuss the sparse and conflicting literature data that could support an observed variability of the surface brightness of the planetary nebula. The puzzling and intriguing characteristics displayed by DT Ser are surely worth additional and more detailed investigations.