Uklonskovite
A colorless sodium-magnesium sulfate-fluoride from Chile, Italy and Uzbekistan.
Intro adapted from Wikipedia (CC BY-SA).
Uklonskovite is an IMA-recognized mineral species in the sulfate class, with the chemical formula NaMg(SO₄)F·2H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/m).
Key properties: specific gravity 2.42; Vitreous luster; optically biaxial.
IMA symbol Ukl, IMA status: approved, named in 1964.
Of very rare occurrence in cavities in clays above the salt strata (Kushkanatau salt deposit, Uzbekistan); on gypsum, sulfate derived from oxidizing sulfides, the other elements from limestones and clays (Cetine mine, Italy).
It is found associated with Glauberite, polyhalite (Kushkanatau salt deposit, Uzbekistan); jurbanite, rostite, tamarugite, ferrinatrite, sideronatrite (Cetine mine, Italy).
The mineral was named to honor Aleksandr Sergeevich Uklonskii (1882–1972), mineralogist, Tashkent University, Tashkent, Uzbekistan, who studied central Asian mineral deposits.