European mixed-alkali glasses are compared with Sayre and Smith's categorization for ancient glass and with the chemical compositions of other prehistoric and later European glasses. The new categories reported here indicate that a wide range of alkali raw materials was used in the production of glasses found in prehistoric European contexts. At least five major chemical categories of glass are now known to have been used in prehistoric and early Roman Europe. A plant species of the genus <i>Salicornia</i> is suggested as a possible alkali source in ancient European glasses. -- AATA