Greenockite

  • Cadmium aperture
  • Cadmium sulfide

Greenockit (obsolete: cadmium aperture) is a rarely occurring mineral from the mineral class of " sulfides and sulfosalts ". It crystallizes in the hexagonal crystal system with the chemical composition of CdS, and is therefore chemically speaking, a cadmium sulfide.

Greenockit usually develops earthy, powdery or crusty coatings, rare small pyramid-shaped crystals in the colors yellow, orange, red, and also greenish and brownish. It occurs along with other sulfide minerals such as sphalerite and galena.

Etymology and history

Greenockit is by Charles Cathcart, 2nd Earl Cathcart named, then better known as Lord Greenock, on whose land it was first found in 1840.

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the Greenockit belonged to the mineral class of " sulfides and sulfosalts " and then to the Department of " sulfides with the molar ratio of metal: sulfur, selenium, tellurium = 1: 1 ," where he the unnamed group II/C.13 formed together with Cadmoselit, Rambergit, wurtzite and wurtzite -2H.

The 9th edition used since 2001, valid and of the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the Greenockit also in the class of " sulfides and sulfosalts " and there in the department of " metal sulfides with the molar ratio M: S = 1: 1 ( and similar ) " a. This division, however, is further subdivided according to the dominant in the metal compound, so that the mineral according to its composition in the subsection " with zinc (Zn ), iron ( Fe), copper (Cu), silver (Ag ), etc., " Finding is where there is the " Wurtzitgruppe " with the system no. Forms 2.CB.45 and the other members Cadmoselit, wurtzite, and Hypercinnabarit Rambergit.

The mainly common in English-speaking classification of minerals according to Dana assigns the Greenockit into the class of " sulfides and sulfosalts " and there in the department of " sulfide minerals ." He is also the " Wurtzitgruppe ( Hexagonal: P63mc ) " with the system no. 02:08:07 and the other members wurtzite, Cadmoselit and Rambergit within the sub-division of " sulfides - tellurides and selenides, including - with the composition AmBnXp, with (m n): p = 1:1" to find.

Modifications and varieties

Greenockit is one of two modifications of cadmium sulfide. The second is the cubic crystalline Hawleyit.

Education and Locations

Greenockit is a typical secondary mineral, that is formed by weathering or metamorphism among other things, sphalerite and covers this crusty. Massive crusting can also be found in cavities of volcanic rocks. Accompanying minerals are mainly prehnite, zeolite and calcite. As a sixteen -sided pyramidal crystals it forms primarily in veins.

Locations include Llallagua in Bolivia, Pribram in the Czech Republic, Bleiberg in Austria, Renfrew, Scotland, and Missouri in the United States.

Crystal structure

Greenockit corresponds structurally to the wurtzite, is thus composed CdS4 tetrahedra. Respectively, a cadmium atom is surrounded by four sulfur atoms, and vice versa. The interconnected tetrahedra are stacked in a hexagonal arrangement.

Use

Although Greenockite is an important addition to cadmium mineral Monteponit and Otavit, however, the mineral findings are too small in spite of the content of 77.8% cadmium, in order to serve as an ore. Cadmium is obtained as a by- product in the zinc extraction.

It has been suggested but not yet proven that Greenockit has been used 2000 years ago as a pigment.

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