Just heard the reason why silver refiners have suspended buying 90% silver. A large defense contractor is manufacturing large numbers of missiles that need highly refined silver. .9999 or even five nines purity. As a result they have a huge need for nitric acid to get that level of purity.                                                                                                                                                                                                                                                                                                                                                                 This created a shortage of nitric acid, especially when over $50 silver caused a huge rush of people selling their sterling silver and constitutional.  The backlog at the refiners was largely as a result of shortages of nitric acid.