Whetstone Mountains                      31.938626°N, 110.424477°W   

Cochise County, Arizona, United States

Fall: June 23, 2009 at 9:22 p.m. MST (UTC -7 hours)

      Classification: Ordinary chondrite (H5 breccia)

History:  A bright fireball with detonations and rumblings was observed by many witnesses.  Carl Hergenrother  estimated magnitude -11 fireball that created shadows, lasted for at least ~2 seconds moving from the southeast part of the sky to the east and downward.  Part of the path was recorded by the All-Sky camera at the UA-Multiple-Mirror Telescope facility on Mt. Hopkins and a security camera in Marana, AZ.  Jack L. Schrader interviewed eye-witnesses and recovered the first 155.86 g stone on the surface of the high desert less than 45 hours after the fall. Within a month of its fall, additional stones were found by Chuck Schrader, Shauna Russell, Robert Ward, Todd Parker, and Michael Farmer. Strewnfield occupies an ~3 x 6 km ellipse, trending N 30° E. Coordinates given are approximately at the center of the strewnfield.

Physical characteristics:  Total known mass as of July 15, 2009 is 2138.74 g among 10 stones.  All except one were recovered as intact individuals with complete fusion crust.  Some stones exhibit regmaglypts. Fusion crust is fresh, matte black. One stone exhibits a fusion crust with a reddish hue (not oxidation) and others contain a few “bluish” spots.

Petrography D. H. Hill (UAz): Well-defined chondrules (200-700 μm) with porphyritic olivine and pyroxene chondrules being most abundant.  Metal grains up to 800 μm and troilite up to 300 μm occur between chondrules in approximately 1:1 proportion.  Many metal grains exhibit fingerlike intergrowth of kamacite and taenite.  Mg-bearing phosphates ~100 x 200 μm occur between chondrules.  A crushed texture is observed that corresponds to a lighter lithology in a darker groundmass.  Shock veins are visible in the hand specimen.  There are two 350 μm chromite-rich clasts.

Mineral compositions and geochemistry: D. H. Hill (UAz) EMP: Olivine (Fa_18.82±0.25); pyroxene (Fs_16.56±0.49Wo_1.77±1.7); kamacite (Ni 6.71% ± 0.28; Co 0.49% ± 0.03), taenite (26% Ni and ~40 % Ni (tetrataenite?); phosphates are mostly Mg-rich with a few Cl-bearing.  

Classification: Ordinary chondrite (H5) breccia; W0