Deep electric blue crystals of stanleyite, a rare vanadium sulphate mineral found in only two localities worldwide. From the type locality: Ragra Mine, Cerro de Pasco, Pasco Department, Peru. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Stanleyite
Stanleyite is an IMA-recognized mineral species in the vanadate class, with the chemical formula V⁴⁺O(SO₄)·6H₂O.
It crystallizes in the orthorhombic crystal system.
Key properties: Mohs hardness 1–1.5; specific gravity 1.95; White streak; optically biaxial.
IMA symbol Stl, IMA status: approved, named in 1980.
Initially found on a museum specimen of patronite from a rich vanadium deposit.
It is found associated with Patronite, pyrite, potassium alum, quartz.
The mineral was named to honor Henry Morton Stanley (1841–1904), noted Welsh–American journalist-explorer.