<p>The jeppeite group, approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA-CNMNC), comprises natural hexatitanate minerals with the general crystal-chemical formula ^VIII<i>A</i>₂^VI<i>M</i>₆O₁₃. Currently, three species are recognised: jeppeite K₂Ti₆O₁₃, nixonite Na₂Ti₆O₁₃, and hopmannite Ba₂(Ti₅Fe)O₁₃. In natural compositions, the polyhedral <i>A</i> site is occupied by the monovalent Na and K, and by the divalent Ba, Ca and Sr, whereas the octahedral <i>M</i> sites are predominantly occupied by Ti⁴⁺ with possible substitutions by Nb⁵⁺, Zr⁴⁺, Fe³⁺, V³⁺, Cr³⁺, Fe²⁺, Mg²⁺ or Mn²⁺. These compositional variations give rise to charge-balanced formula schemes, such as <i>A</i>₂⁺<i>M</i>₆⁴⁺O₁₃, characteristic for jeppeite and nixonite, and <i>A</i>₂²⁺(<i>M</i>₅⁴⁺<i>M</i>²⁺)_Σ6O₁₃, exemplified by hopmannite. Structurally, jeppeite-group minerals crystallise in the monoclinic system, space group <i>C</i>2/<i>m</i>. Their structure consists of an open framework built from zig-zag ribbons of <i>M</i>O₆ octahedra. These corner-sharing ribbons form tunnels that are partially filled, up to two-thirds, by <i>A</i>-site cations. The abundance of synthetic analogues suggests significant potential for additional natural species, which is why nomenclature guidelines have been generated to clarify the classification of future jeppeite-group minerals.</p>