SPRINGWATER

Three masses of 85 pounds, 41 pounds, and 23 pounds totaling 149 pounds were found in a field 100 miles west of Saskatoon in Saskatchewan, Canada. One of the masses was sent by the finder to the Nininger Meteorite Laboratory in Denver where it was verified as being meteoritic.

Springwater has anomalous compositions with respect to olivine fayalite, Sc, Cr, Mn, Zn, and phosphate REE contents. It has a phosphoran olivine composition distinct from most other main-group pallasites, and many of its anomalous chemical compositions suggest that it crystallized from a late-stage, P-enriched, Si-depleted melt that cooled quickly through high temperatures (Boesenberg et al., 2004). In contrast, it has a Sc content that is the lowest among pallasites, and which is consistent with a minimally evolved melt (Mittlefehldt and Rumble, III (2006). The mineral farringtonite was first found in this meteorite. Springwater silicates do not follow an igneous fractionation trend, but instead are more consistent with the loss of Fe through oxidation as a magmatic gas phase was introduced (Wasson and Choi, 2003). These oxidizing gases were concentrated in voids formed by core contraction and mantle collapse during cooling, and they introduced enrichments of the volatile siderophiles Ge and Ga into various pallasitic lithologies.

Springwater and the other PMG-as members may have formed in a more chemically heterogeneous mantle region than normal PMG members, though overall compositional and isotopic similarities still suggest a common parent body for all—possibly as melt residues of the IIIAB iron parent body. However, due to the significantly slower cooling experienced by main-group pallasites compared to IIIAB irons, as well as the younger ages determined for main-group pallasites, a common parent body is not considered to be plausible (E. Scott, 2007). The specimen of Springwater shown above is a 3.5 g partial slice. Below is a museum specimen, a large complete slice of this unique pallasite which reveals the compositional distribution of olivine in FeNi-metal.