Single crystal group of the rare Mn-Mg silicate mineral donpeacorite from the TL in Balmat, New York (Balmat, St Lawrence County, New York, United States of America). Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY 4.0
Donpeacorite
Donpeacorite is an IMA-recognized mineral species in the silicate class, with the chemical formula (Mn,Mg)MgSi₂O₆.
It crystallizes in the orthorhombic crystal system (space group Pbca). It is a member of the Pyroxene structural group.
Key properties: Mohs hardness 5–6; specific gravity 3.36; Vitreous luster; optically biaxial.
IMA symbol Don, IMA status: approved, named in 1982.
Found in manganese-rich siliceous marbles metamorphosed to the upper amphibolite facies.
It is found associated with Tirodite, tourmaline, ferrian braunite, manganoan dolomite, hedyphane, anhydrite.
The mineral was named to honor Dr. Donald R. Peacor (1937{), University of Michigan, Ann Arbor, Michigan, USA.