“…Fission fragments cause linear damage tracks (Figure 3(a)) that range in etchable length depending on numerous factors including host mineralogy and composition [225,226], fission fragment mass [225,227], crystallographic orientation [228], etching time and efficiency [222], and the degree of thermal annealing which may have occurred [229]. For example, the mean etchable length of pristine fission tracks (e.g., unannealed or induced tracks) is ∼8-9 m in volcanic glass (Figure 3(b); Figure 1 in Sandhu et al [198]; Figure 8(b) in Westgate and Naeser [199]; Arias et al [126]; Sandhu and Westgate [128]) and tektites ( Figures 1 and 2 in Storzer and Wagner [218], ∼11 m in zircon [212,230], ∼16 m in apatite [213], and ∼20 m in micas [207,229], although experimentally etched "fossil" (i.e., spontaneous) fission tracks may be substantially shorter in each case, especially due to annealing and track fading [126,128,207,212,213,229,230]. For natural (and synthetic) silicate glasses exhibiting a wide range of chemical compositions, the lengths of fully revealed (i.e., etched) fission tracks are consistently reported as being ∼6-9 m long (e.g., Figures 3(b), 3(d), and 3(e))-including those in hydrated silicic volcanic glass shards [128], tektites (including: australite [216,231], bediasite [218], indochinite [216], and moldavite [128,…”