Evaluating urban micrometeorites as a research resource—A large population collected from a single rooftop

We report the recovery and characterization of a new urban micrometeorite collection derived from rooftop an industrial building in Germany. identified 315 micrometeorites (diameter: 55–515 µm, size peak: ˜150 distribution slope exponent: −2.62). They are predominantly S-type cosmic spherules (97.2%) but also two G-type (0.6%), unmelted coarse-grained single-mineral micrometeorite, eight scoriaceous particles (2.5%) or transitional between porphyritic spherules. Their analysis details how magnetite rim on partially melted is progressively diluted as melt fraction increases during heating. At least 10 contain platinum group nuggets (PGNs). have chondritic compositions depleted volatile Pd. However, single nugget preserves Pd concentrations. suggest that Fe-Ni-S bead originally containing PGN escaped its host cavity wet particle exterior, creating Fe-rich protected evaporation. This layer oxidized forming magnetite—indicating wetting events can affect texture composition micrometeorites. Utilizing well-constrained surface area (8400 m2) age (21 yr), we attempted first global mass flux estimate based data. produced anomalously low values (13.4 t yr–1), even when correcting for losses due to sample processing (<89.7 yr–1). Our value approximately orders magnitude lower than previous estimates, indicating >99% missing, having been lost via drainage cleaning. Rooftop sites limited potential calculations unless problems loss be resolved. collections other advantages, notably exceptionally well-preserved with extremely young terrestrial ages ability extract many accessible sites. Urban should considered complementary Antarctic deep-sea citizen science educational exploitation.