At 10:15 A.M. on Friday, July 14, a fireball traveling in a north-northwest direction exploded over the town of Moss, Norway, in the county of Ostfold, located about 50 km south of Oslo on the east side of Oslofjord. The fall was accompanied by a loud explosion and thunderous rumblings, and numerous calls and reports were made by eyewitnesses to the event. A clear signal was picked up at the Norwegian Seismic Array (NORSAR) in Kjeller, Norway.
Meteorite fragments fell over a wide area. In the vicinity of Rygge, located ~6 km southeast of Moss, the sounds were heard by Ragnar Martinsen as he occupied the outhouse behind his holiday cabin. As he exited, he heard a whistling sound followed by the clatter made by a 36.7 g stone hitting a corrugated metal sheet lying just 2 m away. He contacted astronomers from the Astrophysics Institute of the University of Oslo and from the Norwegian Astronomical Society and invited them to his cabin for their educated opinions of his find—they agreed it was a chondritic meteorite.
On Monday, July 17, with intentions of mowing his lawn, Frode Johansen of Moss, Norway discovered a 752 g stone lodged in a 7 cm-deep hole beneath his plum tree; three broken branches attested to its flight path. The family expressed their intensions to donate the meteorite to the Museum of Natural History in Oslo.
On Wednesday, July 19, a large, partially-crusted fragment was found by a local resident northwest of the Johansen find. After reading about the search for the meteorite in the newspaper, he contacted meteorite hunters Michael Mazur and Bjorn Sorheim of Norway. On Sunday, July 23, the resident met with them to show them a fragment of the fall and to share details of the find location. Subsequently, Michael and Bjorn recovered additional fragments from the original 1.5 kg stone that had shattered upon impact with a fence.
On Sunday evening, July 30, Morten Bilet and Michael Farmer were searching near Moss for additional pieces from this fall. They found ~800 g of fragments that had been strewn about following impact on concrete of a single stone. Some fragments were found in pristine condition up to 20 m away from the point of impact.
On Friday, August 4, a 676 g stone was found which had fallen part way through the roof of a storage warehouse belonging to the Norgesgruppen business in Moss. It had punched a 10-cm hole through the roofing material and was lodged within. Its discovery was made only after rainwater leaked through the hole that it had created. This stone is a natural fit to the Johansen stone, and likewise has been donated to the Museum of Natural History in Oslo.
Portions of the preceeding accounts were gleaned from the Aftenposten: News From Norway (http://www.aftenposten.no/english).
Moss is the sixth witnessed fall of a CO3 chondrite, the first since Kainsez fell in Russia in 1937. Significantly more material was recovered from Kainsez than from Moss—200 kg compared to 3.76 kg, respectively, but the possibility still exists for further recovery of material from Moss.
While the chromite content of fayalitic olivine can provide petrologic type calibration between 3.0 and 3.1, the low Cr value measured in Moss indicates it is higher than 3.1. A petrographic analysis of Moss was conducted by J. Grossman (US Geological Survey, Reston, VA.), which was based on the technique utilized by Chizmadia et al. (2002). This analysis suggests a classification between CO3.5 and CO3.6, and Moss is listed as a CO3.6 in MetBull 91. Petrographic studies by other investigators have provided indications of a lower type, closer to 3.4/3.5; this is according to the Fe–Mg zoning profiles of olivine in type-I chondrules (Greenwood et al., 2007).
Moss contains abundant sub-mm-sized chondrules typical for the CO group, embedded within a fine-grained gray matrix. Extensive low-temperature alteration has likely occurred within the solar nebula, perhaps augmented on the parent body, as evidenced by the wide variation in secondary transformation effects in individual inclusions. Olivine grains within AOAs, and spinel within CAIs have been altered to a range of higher FeO levels, while alteration of CAIs has resulted in the production of secondary minerals such as nepheline replacing primary melilite and/or anorthite, and perovskite converted to ilmenite (Bischoff and Schmale, 2007).
The volume of FeNi-metal and FeS is typical of the proposed classification. As with the CO3.3 Ornans and CO3.1 Kainsaz, Moss contains a low C abundance (0.25 wt%) with a heterogeneous distribution of organic species, all of which have a low molecular weight with a low degree of variation (Pearson et al., 2007). This C abundance is unexpectedly low given its metamorphic grade, and low when compared to the organic inventory of analogous CO3 members such as CO3.5 Lancé. Ornans, Kainsaz, and Moss appear to have experienced unique metamorphic conditions on the parent body. An O-isotopic analysis has been conducted (Franchi and Greenwood, OU), and theses values are consistent with the proposed carbonaceous chondrite group. The specimen of Moss shown above is a 1.97 g crusted fragment.
