The other half of this bolt is stuck at the base of Khazaddum, Mission Gorge. FIXE never marketed any 10mm bolts in the US, but from what I hear they sold hundreds if not thousands. The oversized bolt does not work out so well in a 3/8" hole in hard rock. Luckily the bolt was easy to snap off. Much easier than even a smaller diameter Powers bolt I bashed around as an experiment.
I ruined a carbide drill trying to punch the remains into the hole. Some day this plug can be drilled out to open up the hole for the next generation.