ABSTRACT

Estimation of ²⁶Al (half-life = 705 kyr) content at the time of meteorite fall is required to calculate the terrestrial age of meteorites using the ²⁶Al content. Previous studies (e.g., Cressy, 1971; Hampel et al., 1980) provided empirical equations for the estimation of ²⁶Al content in meteorites at the time of meteorite fall. However, the equations overestimate the ²⁶Al content of howardites and eucrites, which have a high Al content (5-8%). In this study, we present a new simple empirical equation based on the relationship between ²⁶Al content and the content of two main target elements, Al and Si, in 37 falls meteorites from various classes (one howardite, 10 eucrites, 13 diogenites, 8 chondrites, 3 ureilites, and one angrite). The equation estimates the ²⁶Al content of howardites and eucrites at the time of meteorite fall within a 9% difference of the measured ²⁶Al content. This difference is lower than in any other equations presented in previous literature.