Locality: Pyörönmaa pegmatite, Kangasala, Western and Inner Finland Region, Finland Dimensions: 20 mm x 7 mm x 5 mm Fragment of 40 mm pseudomorph mainly composed of synchysite-(Y) with admixture of chernovite/xenotime phase, silica and hematite. Collected 2014. — Photo: Jyrki Autio · CC0
Synchysite-(Y)
Synchysite-(Y) is an IMA-recognized mineral species in the carbonate class, with the chemical formula CaY(CO₃)₂F.
It crystallizes in the orthorhombic crystal system.
Key properties: Mohs hardness 4.5; specific gravity 3.9; Greasy luster; optically uniaxial.
IMA symbol Syn-Y, IMA status: approved, named in 1955.
A rare hydrothermal accessory mineral in alkalic granites and granite pegmatites.
It is found associated with Kainosite, bastnäsite, xenotime, hematite, quartz (Dover, New Jersey, USA).
The name refers to its relation to synchysite-(Ce) and dominant yttrium.