A white vitreous crystal aggregate of the extremely rare Sr carbonate fluoride mineral stenonite from the TL (Ivigtut, Ivittuut, Arsuk Fjord, Sermersooq, Greenland) and only known confirmed locality in Greenland. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY 4.0
Stenonite
Stenonite is an IMA-recognized mineral species in the carbonate class, with the chemical formula Sr₂Al(CO₃)F₅.
It crystallizes in the monoclinic crystal system (space group P2_1/n).
Key properties: Mohs hardness 3.5; specific gravity 3.86; Vitreous luster; optically biaxial.
IMA symbol Sten, IMA status: approved, named in 1962.
A rare mineral found in the contact zone between siderite–cryolite and fluorite-rich rocks.
It is found associated with Jarlite, weberite, jørgensonite, thomsenolite, gearksutite, topaz, muscovite, barite, pyrite, siderite, quartz.
The mineral was named to honor Nicholaus Stenonis (Steno) (1638–1686), Danish scientist, who determined the constancy of interfacial angles of crystals.