Emmonsite Locality: Moctezuma Mine (Bambolla Mine), Moctezuma, Municipio de Moctezuma , Sonora , Mexico ( Locality at mindat.org ) Picture width 3 mm. Collection and photograph Christian Rewitzer This Photo was Mindat.org Photo of the Day - 19th Apr 2008 — Photo: Christian Rewitzer · CC BY-SA 3.0
Emmonsite
A yellowish-green hydrated iron tellurite forming triclinic crystals — also known as durdenite.
Intro adapted from Wikipedia (CC BY-SA).
Emmonsite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Fe³⁺₂(Te⁴⁺O₃)₃·2H₂O.
It crystallizes in the triclinic crystal system (space group P-1).
Key properties: Mohs hardness 5; specific gravity 4.52–4.55; Vitreous luster; refractive index 2.069; optically biaxial.
IMA symbol Ems, grandfathered status — known before the IMA’s founding, named in 1885.
An alteration product formed from earlier tellurium minerals in the oxide zone of some hydrothermal precious metal deposits.
It is found associated with Tellurium, tellurite, rodalquilarite, mackayite, sonoraite, cuzticite, eztlite, gold, pyrite.
The mineral was named to honor Samuel Franklin Emmons (1841–1911), American economic geologist, U.S. Geological Survey.