Ikorskyite KMn<sup>3+</sup>(Si<sub>4</sub>O<sub>10</sub>)·3H<sub>2</sub>O — new mineral from the Khibiny alkaline massif (Kola peninsula, Russia)

Ikorskyite KMn3+(Si4O10)·3H2O is new mineral from agpaitic pegmatite of the Kukisvumchorr Mt. (Khibiny Massif, Russia). The mineral forms radial aggregates of light-brown crystals growing on separate quartz crystals or on romanèchite crusts in association with barite, donneite-Y, strontionite, natrolite, vinogradovite, manganoneptunite and organic matter. The mineral is monoclinic, space group P21/c. a = 5.0714(3), b = 8.2731(5), c = 13.3740(11) Å, β = 93.730(5)°, V = 559.93(5) Å3. The eight most intense lines of the diffractogram are: (I-d[Å]-hkl): 55-7.04-011; 41-4.318-110; 100-4.185-11-1; 24-3.956-021; 28-3.339-004; 19-3.095-014; 30-3.014-113; 70-2.939-12-2. The crystal structure of ikorskyite belongs to a new structure type of minerals and inorganic compounds and belongs to the palygorskite group. The mineral is named in honor of Serafim Veniaminovich Ikorsky (1927–2016), a well-known specialist in the field of organic matter and gases research of the Kola alkaline province.