Gatedalite, Zr(Mn²⁺₂Mn³⁺₄)SiO₁₂, is a new mineral of the braunite group. It is found in hausmannite impregnated skarn together with jacobsite, Mn-bearing calcite, tephroite, Mn-bearing phlogopite,långbanite, pinakiolite and oxyplumboroméite at the Långban Mn-Fe oxide deposit, Värmland, central Sweden. The mineral occurs as very rare, small ≤60 µm), grey, submetallic, irregularly rounded anhedral grains. Gatedalite has a calculated density of 4.783 g/cm³. It is opaque and weakly anisotropic with reflectivity in air varying between 17.1 and 20.8% in the visible spectral range. Gatedalite is tetragonal, space group I41/acd, with the unit-cell parameters a = 9.4668(6) Å , c = 18.8701(14) Å , V = 1691.1(2) ų and Z = 8. The crystal structure was refined to an R1 index of 5.09% using 1339 unique reflections collected with MoKa X-ray radiation. The five strongest powder X-ray diffraction lines [d in Å, (I), (hkl)] are: 2.730(100)(224), 2.367(12)(040), 1.6735(12)(440), 1.6707(29)(048) and 1.4267(16)(264). Gatedalite is a member of the braunite group (general formula AB₆SiO₁₂). It is related to braunite (Mn²⁺Mn³⁺₆SiO₁₂) through the net cation exchange (Zr⁴⁺+Mn²⁺)➝2Mn³⁺, which results from the substitutions Zr⁴⁺ ➝ Mn²⁺ at the 8-fold coordinated site (A in the general formula) coupled with a 2Mⁿ²⁺ ➝ 2Mn³⁺ substitution at the 6-fold coordinated sites (B in the general formula).