Halloran Spring        35°25.63’N, 115°55.62’W

California, United States

Find: March 2019

Classification: Iron meteorite (IIIAB)

History: Found by the owner on their property near Halloran Spring, California, while he was prospecting with a metal detector in March 2019.

Physical characteristics: The meteorite measures approximately 33 × 30 × 15 cm, is irregularly shaped and has an orange-red exterior surface. Mass was readily broken after discovery into numerous silvery-black, ~kg-sized fragments with red-brown exteriors.

Petrography: (C. Herd, UAb) Optical investigation of several specimens including a ~3 × 5 cm polished surface reveals a highly weathered iron meteorite, with veins following and cross-cutting kamacite lamellae boundaries. In some specimens, metal has been completely replaced by magnetite. Measurement of kamacite lamellae, while difficult due to the alteration, suggests a medium to course octahedrite (BW 1.5±0.2 mm; n=9). Several mm-scale lath-shaped inclusions (replaced by oxide) with swathing kamacite are present.

Geochemistry: ICP-MS data, using sample of North Chile (Filomena) as standard (C. Herd and G. Chen, UAb): Ni = 5.6, Co = 0.3 (both wt%); Ir = 1.4, Ga = 72, , Ge = 94, As = 11, W = 0.8, Re = 0.15, Pt = 4.8, Cu = 125, Au = 1.1 (all µ/g).

Classification: (C. Herd, UAb): The highly altered nature of the meteorite is a challenge for classification. Ni, Co, Ga, Ge, and possibly As values have likely been modified by alteration. Other values are consistent with trends observed in IIIAB meteorites. If the meteorite is a IIIAB, then known Au-Ni relationships in IIIAB meteorites indicates that the original Ni content was ~8.5 wt%.

Specimens: Type specimen consisting of 468 g and 249 g representative masses, and 288 g of numerous small fragments, at UAb. Main mass with Peter Goldy.