We recently went on holiday to Turkey and bought a salt and pepper grinder. They were full already and the salt looked like rock salt crystals but were bigger than usual. Back home, we used the salt grinder, only it's not salt! So what on earth is it? It tastes a little bit like citric acid from vague memories of making sherbet at school years ago, but I'm not really an expert on what citric acid tastes like. We are not in Turkey any more, so can't ask in the shop we got it from. Any suggestions?