Gagarinite-(Ce) previously zajacite-(Ce) is a rare radioactive fluoride mineral with formula Na(REExCa1−x)(REEyCa1−y)F6. REE refers to rare-earth elements, mostly those belonging to the lanthanide series. It crystallizes in the trigonal rhombohedral system and has a white vitreous appearance with a conchoidal fracture. It has a Mohs hardness of 3.5 and a specific gravity of 4.44 to 4.55. Zajacite is transparent with refractive indices nω = 1.483 and nε = 1.503. Gagarinite-(Y) is a yttrium-rich analog.
Gagarinite-(Ce) previously zajacite-(Ce) is a rare radioactive fluoride mineral with formula Na(REExCa1−x)(REEyCa1−y)F6. REE refers to rare-earth elements, mostly those belonging to the lanthanide series. It crystallizes in the trigonal rhombohedral system and has a white vitreous appearance with a conchoidal fracture. It has a Mohs hardness of 3.5 and a specific gravity of 4.44 to 4.55. Zajacite is transparent with refractive indices nω = 1.483 and nε = 1.503. Gagarinite-(Y) is a yttrium-rich analog.
It occurs as creamy to white anhedral to subhedral grains in pegmatite and aplite pods or lenses in a peralkaline igneous intrusion.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).