Investigation of magnetic susceptibility and electron paramagnetic resonance of the samples from the region of solid solution Zn2-2xMn2xSiO4 shows that at x <= 0.1 the oxidation state of all manganese ions is +2. At x >= 0.2, manganese is present as Mn2+ and Mn3+. Crystal-chemical studies show that defect formation mechanism changes for 0.1 <= x <= 0.2. Oxidation of part of Mn2+ ions at x > 0.1 causes lumi-nescence concentration quenching in this region of x. (C) 2018 Elsevier B.V. All rights reserved.