Pallasite, PMG (main-group)
standby for albin photo
Found 1915
41° 30' N., 104° 6' W.

A mass of 83 pounds was found 5 miles north of Albin, Wyoming, but was not recognized as a meteorite until 1935. Several additional masses have been found in recent years. The fragmental olivine in this pallasite is very clear with some measuring up to 37 mm across, although the 20.9 g partial slice pictured above contains much smaller crystals. Large olivine clusters are present in portions of this pallasite (Boesenberg et al., 2012).

Cosmic-ray exposure ages for main-group pallasites have been determined based on 36Ar–36Cl in metal (Cook et al., 2010). A wide range of ages has been recorded ranging from ~5 to ~153 m.y., possibly defining two age clusters separated at ~45–85 m.y. Several of the main-group pallasites that have been studied have CRE ages that overlap at 106–122 m.y. (Huber et al., 2011). A calculation for Albin based on 21Ne in olivine gives a similar CRE age of 110 m.y. Formation scenarios and classification schemes for the main-group pallasites can be found on the Imilac page.