La Garita        37°56’N, 106°12’W

Colorado, United States

Find: 2006

Classification: Iron meteorite (ungrouped)

History: A single mass of 1387 g was found on an alluvial fan, 6.7 miles northeast of the town of La Garita, Saguache County, Colorado. In 2006, Mr. Robert Garcia was hunting for projectile points on his relative’s property when he noticed what appeared to be a "cannon ball fragment" lying in the dirt. He picked it up and thought it may be a meteorite after researching them on the internet.

Physical characteristics: The specimen is dome-shaped with a subtle rollover lip and measures 13 × 9 cm across and ~3 cm thick. It has a mostly dark brown-black exterior with a few cm-scale regmaglypts, and red-brown staining in spots.

Petrography: Optical investigation reveals a well-developed Widmanstatten pattern consistent with a fine octahedrite. Troilite inclusions are common.

Geochemistry: Bulk composition: ICP-MS data, using sample of North Chile (Filomena) as standard (C. Herd and G. Chen, UAb): Ni = 12.1, Co = 0.45 (both wt%); Ir = 0.76, Ga = 30, Ge = 117, W = 1.0, Re = 0.11, Cu = 682, Ru = 5.3, Pd = 5.3, Pt = 6.7 (all μg/g).

Classification: (C. Herd, UAb): Ungrouped iron, fine octahedrite. Concentrations of Ni, Ir and Ga appear to be consistent with the IAB group, possibly related to the sLM subgroup of Wasson and Kallemeyn (2002); however, Ge, Pt, Cu and W are anomalously high for the sLM subgroup. Au could not be reliably determined. Classified as ungrouped based on the bulk composition, as well as the lack of silicate inclusions which are typical of IAB iron meteorites.

Specimens: Type specimen of 21.1 g at UAb. Main mass with M. Morgan.