Uasara

Antofagasta, Chile

Find date unknown

Classification: Iron meteorite (IIAB)

History: The seller stated that a woman found the meteorite on a path after seeing a fireball but the moderate weathering is inconsistent with this scenario. The location was between Antofagasta and the Andes. The name Uasara means desert in the Aymaran language spoken by the Aymara people of the Andes.

Petrography: (J.T. Wasson, UCLA) Two polished and etched specimens were examined; they show mottled textures with tiny (~0.1 mm) light and dark "stars", apparently the result of shock followed by reheating. There are compositional halos around sulfides and phosphides. One edge of the sample shows thick flow features that may have originated during atmospheric passage. One edge of the sample shows a very ragged oxidize surface with many pock marks. There are tiny (0.2- 1 mm) holes that pass from this surface into the polished and etched face 1 to 2 mm from the edge of the specimen. Rhabdites are small but common, typical of low-Au IIAB irons.

Geochemistry: 4.45 mg/g Co, 55.5 mg/g Ni, 59.5 μg/g Ga, 178 μg/g Ge, 3.76 μg/g As, 48.2 μg/g Ir, and 0.479 μg/g Au. All elements are within the fields defined by IIAB irons. The Ir content puts the meteorite near the high extreme where it joins two other irons from N. Chile, Sierra Gorda and Negrillos.

Classification: Iron, IIAB. This mass may be paired with Sierra Gorda or Negrillos or both. Given the uncertainty in the discovery location of the new iron, it may have been found near Sierra Gorda but the (poorly defined) location of Negrillos is 340 km distant from Sierra Gorda. The composition of the new iron is slightly closer to that of Negrillos. Because of uncertainty in the pairing, it is being treated as a new iron.

Specimens: 97.9 g type specimen, UCLA; main mass, T. Heitz.