Blue-green crystals of the very rare mineral ransomite associated to yellow magnesiocopiapite crystals from the type locality for ransomite and only one of three known localities worldwide (United Verde Extension Mine, Jerome, Yavapai County, Arizona, United States of America). Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Ransomite
A copper-iron sulfate formed by a mine fire at Jerome, Arizona's United Verde mine.
Intro adapted from Wikipedia (CC BY-SA).
Ransomite is an IMA-recognized mineral species in the sulfate class, with the chemical formula CuFe³⁺₂(SO₄)₄·6H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/c).
Key properties: Mohs hardness 2.5; specific gravity 2.632; Vitreous, pearly on cleavages luster; optically biaxial.
IMA symbol Rns, grandfathered status — known before the IMA’s founding, named in 1928.
Very rare, formed as the result of a mine fire (United Verde mine, Arizona, USA); coating oxidizing copper-bearing pyrite (Campbell shaft, Arizona, USA).
It is found associated with Pyrite, voltaite, römerite (Campbell shaft, Arizona, USA).
The mineral was named to honor Frederick Leslie Ransome (1868–1935), American mining geologist, U.S. Geological Survey and California Institute of Technology, Pasadena, California, USA.