inadvertent gelatin clarification

long, slow cooking has many virtues, not the least of which is gelatin extraction. having accidentally left a pot of assorted chicken bones on the flame for many hours, i came back not to smoking ruin and insurance claims but to a large quantity of stock. i put this in a large ball jar, then into the freezer, with predictable results. the next morning, the stock had frozen and expanded, rending the jar in twain. it didn't look like there were glass shards embedded anywhere, but i left the frozen stock in a sieve to gradually defrost anyway, just in case. many hours later, there was a mass of deflated still-icy gelatin in the sieve, grey with trapped particulates, fat, and other untasty things. in the bowl below, an intensely-flavoured and pellucid stock. not complicated at all (on this matter, also see the cooking issues primer)