A phosphor having a matrix formulation of Li(Al,Ga)O.sub.2 having an atomic ratio of Al to Ga ranging from 75:25 to 5:95, wherein 0.3 to 1.3 atomic percent of Fe.sup.3+ ions are additionally incorporated in the matrix as an active component and Li is present in substantially a 1:1 stoichiometric ratio to the total of Al, Ga and Fe. The phosphor so produced is superior to previously disclosed phosphors when used in an optical code reader to read codes from colored paper.