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Red-Orange Greenockite Microcrystals

The Mineral greenockite

Greenockite is a rare mineral formed mostly of the element cadmium, and it is the only cadmium mineral of importance. Its occurrence is almost always in association with Sphalerite, due to a similar paragenesis, and it often forms as thin coatings on other minerals, especially Smithsonite and Calcite. Greenockite forms in unique crystals that are asymmetrical, with the basal crystal faces forming at wider angles than the top faces.

Greenockite was named in honor of Earl Charles Murray Cathcart, also known as Lord Greenock, a British army general who subsequently became the Governor General of the Province of Canada. Lord Greenock announced the discovery of Greenockite as a new mineral from the excavation of the Bishopton tunnel, near Port Glasgow in Scotland.
Chemical Formula CdS
Composition Cadmium sulfide
Color Yellow, orange, brown, red
Streak Yellow
Hardness 3 - 3.5
Crystal System Hexagonal
3D Crystal Atlas
(Click for animated model) 
Crystal Forms
and Aggregates
Crystals, which are always small, form in hemimorphic hexagonal crystals, often tapered on one end. Crystals are usually horizontally striated. Most commonly encrusting, as a globular lining in cavities, drusy, or as a dusting on matrix.
Transparency Translucent to opaque
Specific Gravity 4.9 - 5.0
Luster Adamantine to resinous
Cleavage 1,1;3,2
Fracture Uneven
Tenacity Brittle
Other ID Marks May fluoresce yellow.
In Group Sulfides; Simple Sulfides
Striking Features Crystals and formation habits, and mode of occurrence
Environment In basalt traprock and hydrothermal ore veins.
Rock Type Igneous, Sedimentary, Metamorphic
Popularity (1-4) 3
Prevalence (1-3) 3
Demand (1-3) 1

Greenockite AUCTIONS
Cadmium Ochre

 -  Variant of the mineral Greenockite with an with an amorphous crystal structure and earthy habit.

Greenockite is the only ore mineral of the element cadmium. Due to the rarity of Greenockite, most cadmium is actually produced as a by-product of lead and zinc ores, especially Sphalerite. Greenockite was once used as a yellow pigment and known as cadmium ochre. Elemental cadmium has many uses, including electronics and batteries (nickel-cadmium), electroplating, and forming of high temperature alloys.

Greenockite is considered a rare collector's mineral, and is much sought after by mineral collectors when in crystallized specimens.

Some of the best Greenockite crystals, often on matrix, have come from the Andesite quarry in Kreimbach-Kaulbach, Rhineland-Palatinate, Germany. Drusy brownish crystals have come from the Kateřina Coal Mine, Radvanice, near Trutnov (Trautenau), Bohemia, Czech Republic; and yellow encrustations from the Paglio Pignolino Mine, Dossena, Bergamo Province, Italy. Small crystals of excellent form were found at the type locality of the Bishopton Tunnel, Strathclyde, Scotland. In Boliva, microcrystal crustings with a bright red color are found in Llallagua, Potosí Department.

In the U.S., yellow Greenockite coatings and crusts are well known from Joplin, Jasper Co., Missouri and the surrounding area in the Tri-State District. Greenockite microcrystals over Smithsonite have been found at Rush, Marion Co., Arkansas; and bright yellow coatings once occurred at Friedensville, Upper Saucon Township, Lehigh Co., Pennsylvania. Perhaps the best U.S. locality in the U.S. for visible crystals is the Summit Quarry, near Springfield, Union Co., New Jersey, where small crystals were found in a limited find in the 1960's. Yellow Greenockite crusts were found in a one-time construction project at the Route 25 Road cut, Trumbull, Fairfield County, Connecticut.

Sphalerite, Prehnite, Calcite, Smithsonite, Pyrite

Sphalerite and Wurtzite - Different crystal form.
Uranium minerals - Exhibit radioactivity that can be picked up by a geiger counter, and often occur in different environments.

greenockite PHOTOS
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