The Julesburg (L3) meteorite

Abstract— The Julesburg chondrite, a single stone weighing 57.9 kg, was found in 1983 in Sedgewick County, Colorado, USA. It contains abundant chondrules and chondrule fragments but little fine‐grained matrix. The olivine composition ranges from Fa1 to Fa25 but a frequency plot of olivine compositions is strongly peaked at Fa23. The low‐Ca pyroxenes range from Fs3 to Fs28 and show no dominant composition. The abundance of clearly defined chondrules, the heterogeneity of the silicates and the presence of glass within chondrules indicate a type 3 chondrite, refined by thermoluminescence data to 3.6. The total iron content of 20.46% is indicative of an L‐group stone. The low noble gas retention ages indicate that this meteorite was outgassed late in its history. This is supported by petrographic evidence of brecciation and shock. Aluminum‐rich spinels within chondrules and inclusions contain up to 2.6% ZnO which suggests that they formed in a volatile‐rich environment.