Getchellite
Encyclopedia
Getchellite is a rare sulfide
of arsenic
and antimony
, AsSbS3, that was discovered by B. G. Weissberg of the New Zealand Department of Scientific and Industrial Research in 1963, and approved as a new species by the International Mineralogical Association
in 1965. Many metal sulfides are grey to black, but a few are brightly colored. Orpiment
is yellow to brownish gold, cinnabar
is deep red and getchellite is a bright orange red.
Melting point
: 340 °C to 355 °C. Boiling point
: Near 470 °C.
atoms to form a trigonal pyramid characteristic of elements in group V of the periodic table
. These (As,Sb)S3 pyramids form 8-membered (As,Sb)8S8 rings which in turn combine to form sheets parallel to (001), with each sulfur atom bonded to two semimetal atoms. The occupancy of the metal sites is disordered, and within the sheets the 8-membered rings are orientated normal to the plane of the sheet. The sheet structure is responsible for the cleavage
and twin planes of getchellite
Unit cell a = 11.949 Å; b = 9.028 Å; c = 10.130 Å; β= 116.15°; V = 980.9 Å3; Z = 8. Space group P21/a.
, in Humboldt County, Nevada
, USA. The purpose of his visit was to collect samples for a study of the relationship between various fairly common sulfides, not to look for new minerals. Getchellite was in some of the samples, but it was not discovered until the rocks were re-examined, a year later. The new mineral was named after the Getchell Mine
, which in turn became the type locality
. Samples from the mine are preserved as type material (a reference material for the mineral), at the Smithsonian National Museum of Natural History, Washington, D.C., USA.
, argillites (lithified muds and oozes) and limestones, near an intrusion of granodiorite
.
Associated minerals are orpiment
, realgar
, stibnite
, cinnabar
and quartz
, as well as galkhaite
, laffittite, chabournéite, christite, lorandite
, marcasite
, barite
, fluorite
and calcite
.
, China
, Iran
, Japan
, Kyrghystan and Russia
.
Sulfide
A sulfide is an anion of sulfur in its lowest oxidation state of 2-. Sulfide is also a slightly archaic term for thioethers, a common type of organosulfur compound that are well known for their bad odors.- Properties :...
of arsenic
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...
and antimony
Antimony
Antimony is a toxic chemical element with the symbol Sb and an atomic number of 51. A lustrous grey metalloid, it is found in nature mainly as the sulfide mineral stibnite...
, AsSbS3, that was discovered by B. G. Weissberg of the New Zealand Department of Scientific and Industrial Research in 1963, and approved as a new species by the International Mineralogical Association
International Mineralogical Association
The International Mineralogical Association is an international group of 38 national societies. The goal is to promote the science of mineralogy and to standardize the nomenclature of the 4000 plus known mineral species...
in 1965. Many metal sulfides are grey to black, but a few are brightly colored. Orpiment
Orpiment
Orpiment, As2S3, is a common monoclinic arsenic sulfide mineral. It has a Mohs hardness of 1.5 to 2 and a specific gravity of 3.46. It melts at 300 °C to 325 °C...
is yellow to brownish gold, cinnabar
Cinnabar
Cinnabar or cinnabarite , is the common ore of mercury.-Word origin:The name comes from κινναβαρι , a Greek word most likely applied by Theophrastus to several distinct substances...
is deep red and getchellite is a bright orange red.
Thermal properties
Getchellite turns darker red when heated, becoming black by the time it reaches its melting point. Close to this temperature it sublimes (changes directly from a solid to a vapour) and recrystallises on cooler surfaces as minute acicular black crystals.Melting point
Melting point
The melting point of a solid is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at standard atmospheric pressure...
: 340 °C to 355 °C. Boiling point
Boiling point
The boiling point of an element or a substance is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid....
: Near 470 °C.
Structure
Each of the semimetal atoms, arsenic and antimony, is bonded to three sulfurSulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
atoms to form a trigonal pyramid characteristic of elements in group V of the periodic table
Periodic table
The periodic table of the chemical elements is a tabular display of the 118 known chemical elements organized by selected properties of their atomic structures. Elements are presented by increasing atomic number, the number of protons in an atom's atomic nucleus...
. These (As,Sb)S3 pyramids form 8-membered (As,Sb)8S8 rings which in turn combine to form sheets parallel to (001), with each sulfur atom bonded to two semimetal atoms. The occupancy of the metal sites is disordered, and within the sheets the 8-membered rings are orientated normal to the plane of the sheet. The sheet structure is responsible for the cleavage
Cleavage (crystal)
Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite crystallographic structural planes. These planes of relative weakness are a result of the regular locations of atoms and ions in the crystal, which create smooth repeating surfaces that are visible both in the...
and twin planes of getchellite
Unit cell a = 11.949 Å; b = 9.028 Å; c = 10.130 Å; β= 116.15°; V = 980.9 Å3; Z = 8. Space group P21/a.
Powder diffraction
| X-Ray Powder Diffraction: | |||||
|---|---|---|---|---|---|
| d spacing | 2.89 | 4.44 | 3.63 | 2.54 | 2.33 |
| relative intensity | 10 | 8 | 7 | 6 | 6 |
Discovery
In August 1962 Weissberg visited the Getchell mine at Adam Peak, about 32 km northeast of GolcondaGolconda
Golconda may be:Places:* Golkonda, ruined city and fortress in India* Golconda, Illinois, town in the United States* Golconda, Nevada, former town in the United StatesOther:* Golconda...
, in Humboldt County, Nevada
Humboldt County, Nevada
Humboldt County is a county located in the U.S. state of Nevada. As of 2007, the population was estimated to be 18,052. Its county seat is Winnemucca.The county was the site of an arrest in 2000 that led to the U.S. Supreme Court decision Hiibel v...
, USA. The purpose of his visit was to collect samples for a study of the relationship between various fairly common sulfides, not to look for new minerals. Getchellite was in some of the samples, but it was not discovered until the rocks were re-examined, a year later. The new mineral was named after the Getchell Mine
Getchell Mine
Getchell Mine is an underground gold mine owned by both Barrick Gold, and Newmont Mining, and is located near Winnemucca, Nevada. The operation consists of two underground mines, the Getchell Mine, and Turquoise Ridge. The mining method currently used is drift and fill.The gold deposit is a...
, which in turn became the type locality
Type locality (geology)
Type locality , also called type area or type locale, is the where a particular rock type, stratigraphic unit, fossil or mineral species is first identified....
. Samples from the mine are preserved as type material (a reference material for the mineral), at the Smithsonian National Museum of Natural History, Washington, D.C., USA.
Environment
At the type locality getchellite is found in an epithermal (formed at low temperature) arsenical gold deposit in a narrow, steeply dipping fault zone cutting across interbedded shalesShalës
Shalës is a municipality in the Elbasan District, Elbasan County, central Albania. The municipality consists of the villages Shalës, Licaj, Kurtalli, Xibrake, Xherie and Kodras....
, argillites (lithified muds and oozes) and limestones, near an intrusion of granodiorite
Granodiorite
Granodiorite is an intrusive igneous rock similar to granite, but containing more plagioclase than orthoclase-type feldspar. Officially, it is defined as a phaneritic igneous rock with greater than 20% quartz by volume where at least 65% of the feldspar is plagioclase. It usually contains abundant...
.
Associated minerals are orpiment
Orpiment
Orpiment, As2S3, is a common monoclinic arsenic sulfide mineral. It has a Mohs hardness of 1.5 to 2 and a specific gravity of 3.46. It melts at 300 °C to 325 °C...
, realgar
Realgar
Realgar, α-As4S4, is an arsenic sulfide mineral, also known as "ruby sulphur" or "ruby of arsenic". It is a soft, sectile mineral occurring in monoclinic crystals, or in granular, compact, or powdery form, often in association with the related mineral, orpiment . It is orange-red in colour, melts...
, stibnite
Stibnite
Stibnite, sometimes called antimonite, is a sulfide mineral with the formula Sb2S3. This soft grey material crystallizes in an orthorhombic space group. It is the most important source for the metalloid antimony...
, cinnabar
Cinnabar
Cinnabar or cinnabarite , is the common ore of mercury.-Word origin:The name comes from κινναβαρι , a Greek word most likely applied by Theophrastus to several distinct substances...
and quartz
Quartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
, as well as galkhaite
Galkhaite
Galkhaite is a rare and chemically complex sulfosalt mineral from a group of natural thioarsenites. Its formula is 64S12, making the mineral the only known natural Cs-Hg and Cs-As phase. It occurs in Carlin-type hydrothermal deposits....
, laffittite, chabournéite, christite, lorandite
Lorandite
Lorandite is a thallium arsenic sulfosalt with the chemical formula: TlAsS2. Though rare, it is the most common thallium-bearing mineral. Lorandite occurs in low-temperature hydrothermal associations and in gold and mercury ore deposits...
, marcasite
Marcasite
The mineral marcasite, sometimes called white iron pyrite, is iron sulfide with orthorhombic crystal structure. It is physically and crystallographically distinct from pyrite, which is iron sulfide with cubic crystal structure. Both structures do have in common that they contain the disulfide...
, barite
Barite
Baryte, or barite, is a mineral consisting of barium sulfate. The baryte group consists of baryte, celestine, anglesite and anhydrite. Baryte itself is generally white or colorless, and is the main source of barium...
, fluorite
Fluorite
Fluorite is a halide mineral composed of calcium fluoride, CaF2. It is an isometric mineral with a cubic habit, though octahedral and more complex isometric forms are not uncommon...
and calcite
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...
.
Distribution
Getchellite is found at the type locality in Nevada, USA, and also in AzerbaijanAzerbaijan
Azerbaijan , officially the Republic of Azerbaijan is the largest country in the Caucasus region of Eurasia. Located at the crossroads of Western Asia and Eastern Europe, it is bounded by the Caspian Sea to the east, Russia to the north, Georgia to the northwest, Armenia to the west, and Iran to...
, China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, Iran
Iran
Iran , officially the Islamic Republic of Iran , is a country in Southern and Western Asia. The name "Iran" has been in use natively since the Sassanian era and came into use internationally in 1935, before which the country was known to the Western world as Persia...
, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, Kyrghystan and Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
.