Emmonsite

Emmonsite is a rarely occurring mineral from the mineral class of ” oxides and hydroxides . ” It crystallizes in the triclinic crystal system with the composition Fe 3 + 2 (Te 4 + O 3) 3 · 2H 2 O [1] , so it is chemically an iron – tellurite .

Emmonsite developed mostly columnar to acicular or dünntafelige crystals , but is also found in the form of fibrous, tufted to spherical or massive mineral aggregates and crusty coating of light green to yellow-green color. The mineral is generally translucent to opaque, but thin layers or small grains can also be transparent. The surfaces of the crystals have a glass-like shine on.

Etymology and history

Was first discovered Emmonsite near Tombstone in Cochise County (Arizona) in the United States and described in 1885 by William Francis Hillebrand , of the minerals by the American geologist Samuel Franklin Emmons . named

Dana and Wells in 1890 described a new mineral from the mine “El Plomo” in the district Ojojona in Honduras and called it Durdenit by Henry S. Durden , who had asked the mineral sample. Comparative analyzes with Emmonsitproben from Tombstone and Cripple Creek (Colorado), however, demonstrated the identity of Durdenit and Emmonsite. The name Durdenit was therefore discredited and is now considered a synonym for the Emmonsite. [5]
Classification

In the now outdated but still in use 8 Edition of Strunz mineral classification by the Emmonsite belonged to the department of ” sulphites , Selenite and Tellurite “where he along with Blakeit , Poughit , Rodalquilarit and Sonorait the unnamed group IV/K.09 formed.

The valid since 2001 and of the International Mineralogical Association used (IMA) 9 Edition of Strunz’schen Mineral classification assigns the Emmonsite in the advanced section of the ” Antimonite , Bismuthite , sulfites, Selenite and Tellurite “one. This is also further divided by the possible presence of additional anions and / or crystal water (H 2 O), so that the mineral according to its composition in the subsection “Tellurite without additional anions, with H 2 O” is to find where it only the “Emmonsite Group” together with Blakeit with the system no. 4.JM.10.

The mostly commonly used in English-speaking classification of minerals by Dana assigns Emmonsite contrast to the class of “sulfates, chromates and molybdates”, but there also in the department of “Selenite, Tellurite and sulphites” one. Here he is the only member of the unnamed group 34.03.03 within the subdivision ” 34.03 Selenite – sulphites – Tellurite “to find.
and Locations
Schieffelinit (white) and Emmonsite from the “Grand Central Mine”, Tombstone District, Arizona (width 3 mm)

Emmonsite forms as a secondary mineral in the weathering ( oxidation ) of tellurite or dignified tellurium . Besides these occur more than parageneses , you still Cuzticit , Eztlit , gold , Mackayit , pyrite , Rodalquilarit and Sonorait on. [3]

A rare mineral formation Emmonsite has so far been demonstrated only in a few localities, where some 40 localities regarded as well known (as of 2013). [6] Apart from its type locality Tombstone, the mineral was still in other places in the Tombstone Hills , Arizona, in Calaveras County in California, near Cripple Creek , Colorado, at several locations in Esmeralda County , Nevada, in the “Lone Pine Mine” in Catron County , near Silver City and the Hidalgo County , New Mexico, in the “Clinton Mine” in Lawrence County in South Dakota, as well as the “Gold Chain Mine” in Juab County are found in Utah.

Other localities are including in Chile, China, Honduras, Japan, and Mexico. [4]
Crystal structure

Emmonsite crystallizes in the triclinic space group P 1 (Raumgruppen-Nr. 2) with the lattice parameters a = 7.90 Å , b = 8.00 Å, c = 7.62 Å, α = 96.7 °, β = 95, 0 ° and γ = 84.5 °, and two formula units per unit cell . [1]

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