An environmentally recovered, mixed Pu-U hot particle from the Thule accident, Greenland has been analyzed by Scanning Electron Microscopy and a large-geometry Secondary Ion Mass Spectrometry based Scanning Ion Imaging (SII) method for simultaneous U-235,U-236,U-238 and Pu-239,Pu-240 isotope compositions. This SII technique permits the visual assessment of the spatial distribution of the isotopes of U and Pu and can be used to obtain quantitative isotope ratios in any user-defined square region up to a few 100 itm in size. The particle measured here has two resolvable U isotopic compositions with a single composition of weapons grade Pu. The bulk of the particle has,, enriched U and weapons-grade Pu with U-235/U-238, U-236/U-238 and Pu-240/Pu-239 of 1.12 +/- 0.04, 0.006 +/- 0.002, 0.054 +/- 0.004, respectively (2 sigma). The Pu isotopic ratio was consistent across the Pu-239/U-238(raw) sample but decreased from 1.99 +/- 0.07 to 0.11 +/- 0.04 (2 sigma) corresponding to the area of the particle with a resolvably different U isotope composition. This portion of the particle has U-235/U-238 U-236/U-238 and Pu-240/Pu-239 ratios of 0.11 +/- 0.04, 0.001 +/- 0.002, and 0.05 +/- 0.04, respectively (2 sigma). The origin of the less enriched U could be environmental that mixed with the particle or heterogeneously enriched U from the weapons. The heterogeneity of hot particles on a micrometer scale highlights the need for spatially resolved techniques to avoid mixing during a bulk or whole particle analysis, as the mixing end members here would have been lost, and the measured ratios would have been inaccurate.