Sharp grammacioliite-(Y) crystals from the type and most famous locality for the mineral: Sambuco Gramaccioliite Site, Valle Stura, Cunoe, Piedmont, Italy — Photo: David Hospital · CC BY-SA 4.0
Gramaccioliite-(Y)
Gramaccioliite-(Y) is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula (Pb,Sr)(Y,Mn)Fe³⁺₂(Ti,Fe³⁺)₁₈O₃₈.
It crystallizes in the hexagonal crystal system (space group R-3). It is a member of the Crichtonite structural group.
Key properties: specific gravity 4.66; Black streak; Metallic luster.
IMA symbol Gmc-Y, IMA status: approved, named in 2001.
Found in hydrothermal quartz veins cutting biotite gneiss (Italy); in metamorphosed bodies of brecciated bauxite and marble (Greece).
It is found associated with Quartz, albite, muscovite, anatase, brookite, rutile, fluorapatite, xenotime, pyrite, a mineral of the synchysite series, dessauite-(Y), senaite (Italy).
The mineral was named to honor Professor Carlo Maria Gramaccioli (b. 1935), University of Milan, Italy and a suffix to designate the dominant rare earth element, Yttrium.