Modoc (1905) meteorite, Scott County, Kansas, USAi

Regional Level Types
Modoc (1905) meteorite	Meteorite Fall Location
Scott County	County
Kansas	State
USA	Country

Ordinary chondrite, veined (L6)
Fell, 2 September 1905; 35 kg, 15-20 stones

After the appearance during the night of a bright fireball accompanied by loud detonations, over the next few days and months perhaps 20 stones were recovered spread over an ~3 km x 11 km area. The largest stone had a mass of 4.9 kg. As these and other stones were subsequently recovered at different times, weathering indices are specimen dependent. The black fusion crust of some samples is unusually thick (~0.5 mm) for chondrites. Friable interiors have a pale grey, almost whitish overall color interrupted by small grains of Fe-Ni metal. Chondrules are present, but often indistinct. Olivine and orthopyroxene are the dominant phases of chondrules and matrix, but significant amounts of kamacite, albitic plagioclase, taenite, and troilite are also present. Lesser amounts of chromite, diopside, apatite, and other opaques have been reported as well. I-Xe (~4.51 Ga) and Sm-Nd (~4.05 Ga) ages indicate ancient formation of an original parent body (OPB) with a subsequent strong, perhaps even catastrophic metamorphic event on the OPB (or a daughter asteroid) during the period of the late lunar bombardment.

Total iron (22.4 wt%) and composition of olivine (Fa23) and orthopyroxene (Fs21) are characteristic of the L group of ordinary chondrites (ordinary chondrites relatively low in total iron). Modoc (1905) is one of 269 witnessed falls listed exactly as an 'L6' with the Meteoritical Bulletin Database (Feb 2016). L chondrites account for roughly 40% of all witnessed meteorite falls with the L6 type as the most common petrologic grade.

Nearly half of the recovered mass has been kept at the American Museum of Natural History in New York, but moderately large masses have been held elsewhere. As of 2000, 6.5 kg were in Washington (USNM), 4 kg in Chicago (FMNH), 2 kg in London (NHM) with other smaller samples elsewhere.

What's in a name? For over four decades, "Modoc" was the meteorite's recognized official name. However, one of the meteoritic stones subsequently found in the same area was eventually recognized by Nininger to be an entirely separate meteorite. This second meteorite, an H6 chondrite, was named "Modoc (1948)" and, consequentially, "Modoc (1905)" soon became the new official name of the 1905 fall.

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References