Figure 1.

Laser Ablation Resonance Ionization Mass Spectrometry (LARIMS) isochron of lunar analog Duluth Gabbro. Each point is a ~100 µm spot analysis from within a single 1 × 1 cm sample of the Duluth Gabbro. Ellipses show the 1σ confidence intervals; all spot analyses in which ⁸⁵Rb, ⁸⁶Sr, ⁸⁷Sr, ⁸⁷Rb, and ⁸⁸Sr were detected at twice the background level are shown and included in the fit. The age, found from the slope of the best fit line, is within 1σ of previous TIMS measurements of 1096 ± 14 Ma, although the precision is only 300 Ma.37, 45