Tetradymite is a

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...

consisting of

bismuth Bismuth is a chemical element; it has symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental bismuth occurs nat ...

tellurium Tellurium is a chemical element; it has symbol Te and atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens. It is occasionally fou ...

and sulfide, Bi₂ Te₂ S, also known as telluric bismuth. If

sulfur Sulfur ( American spelling and the preferred IUPAC name) or sulphur ( Commonwealth spelling) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms ...

is absent the mineral is tellurobismuthite and the formula is then Bi₂Te₃. Traces of

selenium Selenium is a chemical element; it has symbol (chemistry), symbol Se and atomic number 34. It has various physical appearances, including a brick-red powder, a vitreous black solid, and a grey metallic-looking form. It seldom occurs in this elem ...

are usually present. Crystals are

rhombohedral In geometry, a rhombohedron (also called a rhombic hexahedron or, inaccurately, a rhomboid) is a special case of a parallelepiped in which all six faces are congruent rhombus, rhombi. It can be used to define the rhombohedral lattice system, a Ho ...

, but are rarely distinctly developed; they are twinned together in groups of four; hence the name of the mineral, from the Greek for fourfold. There is a perfect

cleavage Cleavage may refer to: Science * Cleavage (crystal), the way in which a crystal or mineral tends to split * Cleavage (embryo), the division of cells in an early embryo * Cleavage (geology), foliation of rock perpendicular to stress, a result of ...

parallel to the

basal plane In crystallography, crystal structure is a description of ordered arrangement of atoms, ions, or molecules in a crystalline material. Ordered structures occur from intrinsic nature of constituent particles to form symmetric patterns that repeat a ...

and the mineral usually occurs in foliated masses of irregular outline. The color is steel-gray, and the luster metallic and brilliant. The mineral is very soft (H = 1.52) and marks paper. The specific gravity is 7.2 to 7.9. The type locality is Zupkov (Zsubko; Schubkau), Stredoslovenský Kraj,

Slovak Republic Slovakia, officially the Slovak Republic, is a landlocked country in Central Europe. It is bordered by Poland to the north, Ukraine to the east, Hungary to the south, Austria to the west, and the Czech Republic to the northwest. Slovakia's ...

where it was reported in 1831. It was first found, in 1815, at

Telemark Telemark () is a Counties of Norway, county and a current electoral district in Norway. Telemark borders the counties of Vestfold, Buskerud, Vestland, Rogaland and Agder. In 2020, Telemark merged with the county of Vestfold to form the county o ...

Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of the Kingdom of ...

. It often occurs in high temperature

hydrothermal Hydrothermal circulation in its most general sense is the circulation of hot water (Ancient Greek ὕδωρ, ''water'',Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with th ...

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

veins Veins () are blood vessels in the circulatory system of humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and fetal c ...

associated with native

gold Gold is a chemical element; it has chemical symbol Au (from Latin ) and atomic number 79. In its pure form, it is a brightness, bright, slightly orange-yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal ...

and in

contact metamorphic Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of chem ...

deposits.

References

Attribution:

External links

{{Authority control Bismuth minerals Telluride minerals Sulfide minerals Tetradymite group Trigonal minerals Glances Minerals in space group 166