Willow grove: A unique nickel-rich ataxite from Victoria, Australia

Abstract

The Willow Grove meteorite is a new ungrouped iron meteorite from Victoria, Australia, with an extremely high Ni content (28%). It has a lath martensite structure, in contrast to the plate martensite shown by Tishomingo, a compositionally similar ungrouped iron meteorite with a slightly higher Ni content (32%). Despite the meteorite's unique texture, it has not been possible to estimate the rate at which the meteorite cooled, either before or after the transformation to martensite. Willow Grove also shows a pervasive network of microcracks most likely caused by terrestrial stress corrosion. Like Tishomingo, Willow Grove is depleted in volatiles. It is suggested that the volatiles were lost during asteroid processing, the high temperature possibly produced by an impact event.