To provide basic research into the utilization of mine tailings as supplementary cementitious materials in cement, the pozzolanic activity and hydration properties of quartz-a common mineral phase in mine tailings-after undergoing mechanical grinding were investigated. In this study, a supplementary cementitious material was obtained using the mechanical grinding of quartz. Prolonged grinding resulted in a gradual increase in the pozzolanic activity index and percentage of dissolution in an alkaline solution, as well as a reduction of the relative crystallinity. The particle size appeared to have reached a limit after 80 min of grinding; however, the specific surface area reached its limit after 120 min of grinding, which was mainly due to the continual increase in pore volume of the micropores and mesopores from the grinding process. As an active supplementary cementitious material, the hydration product of ground quartz was an amorphous C-S-H gel in the presence of calcium hydroxide. This study provides a research basis for investigating the pozzolanic activity and hydration properties of ground quartz, which is beneficial to an evaluation of the pozzolanic activity of siliceous mine tailings after mechanical activation. (C) 2020 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.