Botryogen , Butlerite , Copiapite , Parabutlerite Locality: Mina Santa Elena, Alcaparrosa, San Juan, Argentina Size: small cabinet, 6.5 x 5.6 x 4.5 cm Botryogen, Copiapite, Butlerite and Parabutlerite A very rich specimen with numerous sharp clusters of Botryogen crystals to 1 cm, embedded in matrix of minutely crystallized Parabutlerite with other associated species. Many crystals are sharp and translucent. THis is a rich and colorful specimen with whopping crystals for the species! — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Butlerite
Butlerite is an IMA-recognized mineral species in the sulfate class, with the chemical formula Fe³⁺(SO₄)(OH)·2H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/m).
Key properties: Mohs hardness 2.5; specific gravity 2.55; Pale yellow streak; Vitreous luster; optically biaxial.
IMA symbol Btl, grandfathered status — known before the IMA’s founding, named in 1928.
Rarely formed from the oxidation of pyritic ore; may be formed under fumarolic conditions from mine fires.
It is found associated with Parabutlerite, copiapite, fibroferrite, other iron sulfates.
The mineral was named to honor Professor Gurdon Montague Butler (1881–1961), American mining geologist, University of Arizona, Tucson, Arizona, USA.