The analysis of the historic stony meteorite “Mocs” that fell on 3 February 1882 was carried out under high vacuum and ultra low beam current. This was done to avoid any kind of sample preparation including conductive coating. Analyses were performed at 6 kV and < 10 pA beam current, still resulting in a count rate of 2 kcps, produced by the XFlash® FlatQUAD. (Sample courtesy: L. Ferrière, Natural History Museum, Vienna, Austria)
First image is a composite overview EDS element map and SE micrograph overlay, size 800x600 pixels, 2 μm pixel size, acquired within 17 min. Overlapping peaks (Pb M, S K) were deconvolved with an automatic routine. It allows to discriminate sulfides (yellow) from lead contamination. The latter is a result of old polishing. The white rectangle indicates the area analyzed in the detail map.
The composite EDS map of the detail highlighted in the previous map shows showing carbon features <300 nm in green. These indicate soot contamination by heating with coal-fired furnaces in former times. The map was recorded with 130 nm pixel size within 5h 10 min.
The second study was carried out on a piece of the Tissint Martian meteorite that fell in Morocco on July 18, 2011. Tissint is only the fifth Martian meteorite that people have witnessed falling to Earth, the last time such an event happened was in 1962. Thus, the scientific value of these unique meteorites excludes sample preparation. The Tissint Martian meteorite was analyzed overnight using 4 kV and 55 nm pixel size. The mapped area reveals a thin coating and local enrichment of carbon and nitrogen which are associated with topographic features.