According to chemical and structural analyses of bloomery slags from Presov-Pavlovicovo Square, dating from the Late Romano-Barbarian of Migration Periods, and those from Nemcovce (Early Middle Ages), the smelters exploited in the first case very pure limonitic ores from surface deposits. In the latter case, the slags represent waste from smelting of inferior quality ore containing a great deal of silica gangue; the efficiency of the bloomery process, however, increased. -- AATA