Progress in the Crystal Chemistry of New Fumarolic Minerals Discovered in the 2014–2024 and Their Synthetic Analogues

The review presents the results of the extensive study of the new anhydrous minerals discovered in the fumaroles of the Tolbachik volcano (Kamchatka) during the last 10 years. The conditions for the synthesis of fumarolic mineral analogues and the features of their crystal chemistry are described. The emphasis is given to the minerals containing sulfate or vanadate anions, the discovery of which gave rise to large families of inorganic compounds and materials with rich and interesting crystal chemistry. A separate section is devoted to the progress in the field of high-temperature X-ray diffraction study of exhalative minerals. Several rare topotactic single crystal to single crystal (SC–SC) transformations detected for vergasovaite and aleutite are described.