Black acicular crystals of the very rare Fe-V silicate mineral erlianite from the type and only known locality worldwide: Harhada Mine, Wenduermiao, Erenhot County, Xilin Gol League, Inner Mongolia, China (Peoples Republic). Ex Vandenbroucke Museum collection specimen, from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Erlianite
Erlianite is an IMA-recognized mineral species in the silicate class, with the chemical formula Fe²⁺₄Fe³⁺₂Si₆O₁₅(OH)₈.
It crystallizes in the orthorhombic crystal system.
Key properties: Mohs hardness 3.7; specific gravity 3.11; Brownish black streak; Silky luster; optically biaxial.
IMA symbol Ern, IMA status: approved, named in 1985.
Occurs as coatings along fault surfaces cutting a low-grade metamorphosed volcanic-sedimentary iron formation; presumably formed in a high-pressure, low-temperature environment.
It is found associated with Minnesotaite, stilpnomelane, quartz, magnetite, siderite, albite, deerite.
Presumably for the town of Erlian, China.