Fe, Ni, Co, and Cu in FeNi alloys of H Chondrites

This publication presents the results of chemical analyses of 173 FeNi alloy grains from four selected H ordinary chondrites: Thuathe, Chergach, Gao-Guenie and NWA 4555. Based on performed analyses and calculations, the following average chemical composition of the FeNi alloy was determined [in wt.%]: Fe - 90.75%; Ni - 8.80%; Co - 0.35%; Cu - 0.03%. The content of Cu and Co depends on the nickel content in the FeNi alloy. The low-nickel alloy represented by kamacite is enriched in cobalt (average content 0.38%) and depleted in copper (0.01%), while the high-nickel alloy, represented mainly by taenite, is characterized by a low content of cobalt (0.08%), and a significant enrichment in copper (0.16%). Based on these data, it is possible to approximate the resources of these metals in the parent bodies of these chondrites. For example, for the asteroid (143624) 2003 HMi6, which is classified as a Near Earth Object (NEO), such resources are [in Mg]: Fe - 2.4 · 109, Ni - 2.3 · 108, Co-9.2 · 106, Cu-7.9 · 105.

Meteorite from Astomulyo Village, Central Lampung, Indonesia: Investigation of its chemical properties

In early 2021, a rare extraterrestrial object passed at high speed, followed by a powerful boom, with a bright flare crossing the atmosphere and falling in Astomulyo Village, Punggur, Central Lampung, Indonesia. This object has been scientifically determining as a meteorite. Toward the spot where we first found it, we presented this object named Astomulyo meteorite. This research investigated its chemical properties using an X-ray fluorescence (XRF) analyzer. As the result, the major composition of this meteorite is Si (28.3-27.1%), Fe (22.1-19.8%), Mg (17.3-15.2%), Al (2.9-2.4%), Ca (1.7-1.9%), and S (1.0-0.97%). Its minor elements are Mn, Ni, Cr, P, and some trace elements such as Co, Ti, Sb, Sn, V, Cd, Zn. This meteorite suggested classifying as the H-Chondrites group. Fe, Ni, Al, and Ti enrichment occur on the meteorite’s surface. It is probably related to this meteorite origin and continuously processes until it falls to the Earth’s surface.

The Kumtag Meteorite Strewn Field

The Kumtag meteorite strewn field was found in the Kumtag desert, 132 kilometers south of Hami city in the Xinjiang province, China. It is an ellipse of 2.5×7.9 km, with a long axis extending along the northeast-southwest direction. The largest individual meteorite of the strewn field weights about 10 kg; the smallest individual has as mass of only 27 g. In total more than 100 individuals with a total mass of more than 180 kg were collected. The Kumtag meteoroid entered the atmosphere in the direction Northeast-Southwest. All meteorites collected in this strewn field are samples from the same unique meteorite shower. The Kumtag meteorite is an H5 ordinary chondrite with a shock stage S2, and a weathering grade W2. The cosmic ray exposure age of Kumtag is 6.7± 0.8 Ma, which is rather typical for H chondrites and which indicates that Kumtag was derived from the massive impact event on its parent body ~7 Ma ago. A significant He amount has been released during certain unknown processe(s) before the Kumtag meteorite was ejected from its parent body.

Mössbauer Study of Weathered H-meteorite from the Desert of Oman

A number of meteorites from the desert of Oman, classified as H-chondrites, with known and unknown ages, were studied by using 57Fe Mössbauer spectroscopy to determine their Fe3+-bearing compositions. Mössbauer spectra measured at 78 K were composed of paramagnetic doublets superimposed on magnetic sextets. The doublets are assigned to the silicate minerals olivine and pyroxene and Fe3+ phases. The magnetic sextets in most samples showed the presence of at least three magnetic phases, namely troilite, magnetite and kamacite, which commonly exist in most ordinary chondrites. The relative amounts (area %) of Fe3+ in the known-age meteorites, determined from the Mössbauer spectra, were plotted against their terrestrial ages. The plot was used to estimate the terrestrial ages of meteorites with unknown terrestrial age.