A number of chemical reactions (mass-action expressions) have been proposed to describe serpentinization of olivine in terrestrial serpentinites. Some have been applied to interpreting the formation of serpentine-group minerals in CM carbonaceous chondrites. The widely used olivine + pyroxene → serpentine (ol + px → srp) reaction is quantitatively inconsistent with observed ratios of olivine to pyroxene and olivine to serpentine in CM carbonaceous chondrites. The reaction of 5ol → 2srp is most consistent with constraints from textural observations at the scale of individual partial and complete pseudomorphs of serpentine after coarse olivine in CM chondrites, observed co-variations in modal abundances of reactant and product minerals in CM chondrites, and experimental geochemical kinetics. Furthermore, the 5ol → 2srp reaction provides insight into the mobility of solute species in the aqueous alteration environment of CM carbonaceous chondrites.

Small stones were recovered from a meteorite shower observed in Cameroon on November 13, 1952. The majority are LL6 specimens, Galim (a), but one is a chondrule-rich enstatite chondrite, Galim (b). Petrology and mineral chemistry were determined on polished sections of both types. Galim (a) has undergone multiple brecciation. During the first, chromite apparently recrystallized in healed fractures under more reducing conditions than those which prevailed when the silicates recrystallized. Galim (b) shows some features of petrologic type 3 but differs considerably from the other unequilibrated E chondrites. It is suggested that Galim (a) and Galim (b) belong to the same meteorite shower.

Metal particles in the Bachmut chondrite may be subdivided into large (hundreds of μm in size) and small (1–10 µm in size) varieties. They differ in the ratio of their constituent phases, in structure, and in chemical composition. Large particles are richer in Ni than small ones, the latter being characterized by an abnormally high Cu content. It is suggested that different pre-accretion histories were responsible for producing the various types of metal grains, and that, during post-accretion thermal history, temperatures were too low to cause elemental redistribution among the grains.

High-resolution imaging of electron-transparent samples using a scanning electron microscope, here termed low voltage (LV) STEM, is a new and valuable technique for studying Earth and planetary materials. The most effective method of LV-STEM imaging uses a pair of electron detectors positioned side-by-side beneath the thin sample. The detector directly underlying the sample forms bright-field images dominated by mass-thickness contrast. Activation of the detector offset from the sample yields dark-field images with a greater component of atomic number contrast. LV-STEM images with significant diffraction contrast can also be obtained, but require careful positioning of the sample relative to the electron detectors. In this study LV-STEM was used successfully to image sub-μm sized kaolinite crystals and tens of nm-sized etch pits on the gold-coated surfaces of weathered feldspar grains. Dark-field LV-STEM was also especially effective for characterizing very fine-scale intergrowths of Mg- and Fe-rich phyllosilicates within uniformly thin samples of the Murchison meteorite prepared using the focused ion beam (FIB) technique. LV-STEM is a quick and easy method for characterizing the morphology and internal structure of mineral and rock samples and may prove to be especially useful in geomicrobiology research.

Precise data from instrumental observations of fireballs, especially those for really bright bolides, provide information about the population and physical properties of meteoroids, i.e. fragments of asteroids and comets, colliding with the Earth's atmosphere. An overview of what is known about meteoroids and their parent bodies from analysis of bolides producing meteorite falls, especially from the instrumentally observed meteorite falls, was a topic of this invited contribution. At present, atmospheric and orbital information with different degree of reliability and precision for these meteorite falls is known for only 24 cases. This topic was described in detail in the review work of Borovička, Spurný and Brown (2015) (Borovička et al., 2015). However, this work contains all instrumentally documented falls until end of 2013. To bring this work up to date, two new instrumentally observed meteorite falls in 2014, the Annama meteorite fall in Russia on 18 April 2014 and the Žďár nad Sázavou meteorite fall in the Czech Republic on 9 December 2014, are presented and commented in this paper. Especially the second case is mentioned in more detail including still unpublished data. Statistical analyses resulting from all 24 instrumentally documented falls are also mentioned.

Samples of mid-Ordovician Durness Group limestone from Skye yield micrometeorites in the magnetic fraction after dissolution in acid. The micrometeorites are concentrated in the upper part of the sequence, in the Arenig Balnakeil and Croisaphuill formations. This finding is consistent with their stratigraphic distribution determined previously in the Durness district. A single sample of contemporaneous limestones from the Highland Border Fault Zone also yielded a micrometeorite. These observations suggest an elevated flux of meteoritic matter, shortly before the greatest concentration of meteorites in the geological record in the mid-Ordovician of Sweden.

The advent of simultaneous energy dispersive X-ray spectroscopy (EDS) data collection has vastly improved the phase separation capabilities for electron backscatter diffraction (EBSD) mapping. A major problem remains, however, in distinguishing between multiple cubic phases in a specimen, especially when the compositions of the phases are similar or their particle sizes are small, because the EDS interaction volume is much larger than that of EBSD and the EDS spectra collected during spatial mapping are generally noisy due to time limitations and the need to minimize sample drift. The backscatter electron (BSE) signal is very sensitive to the local composition due to its atomic number (Z) dependence. BSE imaging is investigated as a complimentary tool to EDS to assist phase segmentation and identification in EBSD through examination of specimens of meteorite, Cu dross, and steel oxidation layers. The results demonstrate that the simultaneous acquisition of EBSD patterns, EDS spectra, and the BSE signal can provide new potential for advancing multiphase material characterization in the scanning electron microscope.

This research deals with the fall of the Sikhote-Alin iron meteorite on the morning of 12 February 1947, at about 00:38 h Utrecht, in a remote area in the territory of Primorsky Krai in Eastern Siberia (46°09′36″N, 134°39′22″E). The area engulfed by the meteoritic fall was around 48 km2, with an elliptic form and thousands of craters. Around the large craters the trees were torn out by the roots and laid radially to the craters at a distance of 10–20 m; the more distant trees had broken tops. This research investigated through dendrocronology n.6 Scots pine trees (Pinus Sibirica) close to one of the main impact craters. The analysis of growth anomalies has shown a sudden decrease since 1947 for 4–8 years after the meteoritic impact. Tree growth stress, detected in 1947, was analysed in detail through wood microsection that confirmed the winter season (rest vegetative period) of the event. The growth stress is mainly due to the lost crown (needle lost) and it did not seem to be caused due to direct damages on trunk and branches (missing of resin ducts).

Arguing from a critical reading of the text, and scientific evidence on the ground, the authors show that the myth of Phaethon – the delinquent celestial charioteer – remembers the impact of a massive meteorite that hit the Chiemgau region in Bavaria between 2000 and 428 BC.

The report of Commission 15 was prepared primarily by the chairpersons of its two working groups: the Minor Planet Working Group and the Comet Working Group. In particular, the Minor Planet section was created by A. Cellino with a little help from E. Tedesco and the Comet section by T. Yamamoto with the assistance of D. Bockelée-Morvan, W. Huebner, A. Bhardwaj, D. Biesecker, L. Jorda, H. Kawakita, H. U. Keller, H. Kimura, A. Kouchi, and D. Prialnik. E. Tedesco was responsible for the Introduction, final editing, and merging of the two reports.

Within the near-Earth object population, one finds asteroids, comets, and meteorites thereby placing the NEO population at the center of the ACM conference. The longstanding gulf between the spectral properties of S-type asteroids and ordinary chondrite meteorites appears to be bridged, where the observational data are consistent with a space weathering type process. As much as 30% of the entire NEO population may reside in orbits having a Jovian Tisserand parameter <30, and among these roughly half are observed to have comet-like physical properties in terms of their albedos and spectra (taxonomy). Thus 15±5% of the entire NEO population may be comprised by extinct or dormant comets.

Antarctica is currently the most productive region of the Earth for the recovery of meteorites and over 9800 specimens have been found there, most of these since 1969. This material consists of meteoritic fragments representing a much smaller, but unknown, number of distinct meteorites. The particular climatic and environmental conditions of Antarctica result in the recovery of a much larger fraction of the extraterrestrial material that falls to Earth than would be the case in other regions. Remarkable concentrations of meteorites are found in some ‘blue ice’ areas resulting from the movement and ablation of the ice. Most meteorites are believed to have been derived from asteroids less then 200 km in diameter. The discovery in Antarctica of meteorites of lunar material proved that other sources are possible. Indeed two meteorites from Antarctica may have come from the planet Mars. Antarctic meteorites have much older terrestrial ages than non-Antarctic specimens and may be used to obtain information on the movement of the ice sheets in the past.

A meteorite impact crater in the Sirente mountains, central Abruzzo has recently been dated to the four/fifth century AD. The author shows that this catastrophic event can be equated with a locally preserved legend which describes how local people saw a new star fall to earth during a pagan festival. Their conversion to Christianity was expeditiously effected … .