Aguilarite - Locality: San Carlos Mine, La Luz, Mun. de Guanajuato, Guanajuato, Mexico - specimen height is 3.9 cm — Photo: Terry Wallace · Public domain
Aguilarite
Aguilarite is an uncommon sulfosalt mineral with formula Ag4SeS. It was described in 1891 and named for discoverer Ponciano Aguilar.
Intro adapted from Wikipedia (CC BY-SA).
Aguilarite is an IMA-recognized mineral species in the sulfide class, with the chemical formula Ag₄SeS.
It crystallizes in the monoclinic crystal system (space group P2_12_12_1). It is a member of the Acanthite structural group.
Key properties: Mohs hardness 2.5; specific gravity 7.4–7.53; Metallic. Anisotropism: Very weak or isotropic. R1 –R2: (400) 34.8–35.1, (420) 34.7–35.2, (440) 34.6–35.2 luster.
IMA symbol Agu, grandfathered status — known before the IMA’s founding, named in 1891.
An uncommon, relatively low-temperature, mineral in hydrothermal deposits rich in silver and selenium, but manifestly deficient in sulfur.
It is found associated with Acanthite, naumannite, silver, stephanite, proustite, pearceite, calcite, quartz.
The name commemorates Ponciano Aguilar (1853–1935), Superintendent of the San Carlos mine, Guanajuato, Mexico, where the material was originally found.