Emmonsite crystals
Emmonsite crystal spray from the Moctezuma Mine, Moctezuma, Municipio de Moctezuma, Sonora, Mexico. Photo: Christian Rewitzer
 

Emmonsite was first described in 1885 for an occurrence in the Tombstone District, Cochise County, Arizona. It was named for the American geologist, Samuel Franklin Emmons, (1841–1911), of the United States Geological Survey.

Emmonsite is found, often with quartz or cerussite in the Tombstone, Arizona area. It is also associated with native tellurium, tellurite, native gold, pyrite, rodalquilarite, mackayite, sonoraite, cuzticite and eztlite.

Occurrence: An alteration product formed from earlier tellurium minerals in the oxide zone of some hydrothermal precious metal deposits.

Formula: Fe2(TeO3)3·2(H2O)
Color: Yellowish-green; light yellow-green in transmitted light.
Crystal system: Triclinic
Crystal habit: in rosettes and sprays; in fibrous globular aggregates and crusts, microcrystalline massive.
Mohs scale hardness:    5

 
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