a mineral of the group of complex fluorides. Its chemical composition is NaCaYF6; the yttrium can be partially replaced by elements of the cerium group, and the fluorine can be partially replaced by chlorine and the (OH)− group.
Gagarinite is a rare mineral. It crystallizes in a trigonal system and is characterized by small hexahedral crystals and grainy aggregates. It is colorless or pinkish yellow. Its hardness on the mineralogical scale is 4–4.5; its density is 4,180–4,520 kg/m3. Gagarinite is found in alkaline granites or the pegmatites that are associated with them. It was discovered in 1961 in Kazakhstan and the Tuva ASSR. The mineral is named in honor of Iu. A. Gagarin.
REFERENCEStepanov, A. V., and E. A. Severov. “Gagarinit—novyi redkozemel’nyi mineral.” Dokl. AN SSSR, 1961, vol. 141, no. 4, pp. 954-57.
G. P. BARSANOV