Hydroterskite is a rare zirconium silicate mineral, related to terskite (hence its name), with the formula Na<sub>2</sub>ZrSi<sub>6</sub>O<sub>12</sub>(OH)<sub>6</sub>. It was discovered in the Saint-Amable sill near Montréal, Québec, Canada. It is hydrous, when compared to terskite. Chemically similar minerals include litvinskite and kapustinite.