Petersite-(Y)
Petersite-(Y) is an IMA-recognized mineral species in the phosphate class, with the chemical formula Cu₆Y(PO₄)₃(OH)₆·3H₂O.
It crystallizes in the hexagonal crystal system. It is a member of the Mixite structural group.
Key properties: specific gravity 3.41; Highly vitreous on {1010} to dull on {0001} luster; optically uniaxial.
IMA symbol Pts-Y, IMA status: approved, named in 1981.
Found as a very rare secondary mineral in biotite-plagioclase hornfels near a diabase stock cutting Triassic sediments (Laurel Hill, New Jersey, USA).
It is found associated with Chalcopyrite, malachite, chrysocolla, hematite, chlorite, “opal” (Laurel Hill, New Jersey, USA); malachite, quartz (Herrensegen mine, Germany).
The mineral was named to honor the brothers Thomas A. Peters (1947–), Curator of minerals at the Paterson Museum, Paterson, New Jersey, USA, and Joseph Peters (1951–).