Getchellite | |
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General | |
Category | Sulfide mineral |
Formula (repeating unit) | AsSbS3 |
IMA symbol | Get [1] |
Strunz classification | 2.FA.35 |
Dana classification | 2.11.1.2 |
Crystal system | Monoclinic |
Crystal class | Prismatic (2/m) (same H-M symbol) |
Space group | P21/a |
Identification | |
Formula mass | 293.81 g/mol |
Color | Dark red, sometimes with a purple to green iridescent tarnish |
Crystal habit | Subhedral crystals and massive with a platy texture |
Twinning | Simple and polysynthetic twins with the twin plane and composition plane parallel to {001} |
Cleavage | Perfect on {001} |
Fracture | Splintery |
Tenacity | Sectile; cleavage flakes are flexible and inelastic |
Mohs scale hardness | 1.5 to 2 |
Luster | Vitreous to pearly on cleavage surfaces, otherwise resinous |
Streak | Orange red |
Diaphaneity | Transparent |
Specific gravity | 3.92 (observed) 4.0 (calculated) |
Optical properties | Biaxial (+), 2V=46° |
Refractive index | n = 2.720. Dispersion r > v strong |
Melting point | 340 °C to 355 °C |
Other characteristics | Not radioactive |
References | [2] [3] [4] |
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.
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 vapor) and recrystallizes on cooler surfaces as minute acicular black crystals.
Melting point: 340 °C to 355 °C. Boiling point: near 470 °C. [5]
Each of the semimetal atoms, arsenic and antimony, is bonded to three sulfur 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. [6] 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 [7] Unit cell a = 11.949 Å; b = 9.028 Å; c = 10.130 Å; β= 116.15°; V = 980.9 Å3; Z = 8. [6] Space group P21/a. [8]
X-Ray Powder Diffraction: [5] | |||||
---|---|---|---|---|---|
d spacing | 2.89 | 4.44 | 3.63 | 2.54 | 2.33 |
relative intensity | 10 | 8 | 7 | 6 | 6 |
In August 1962 Weissberg visited the Getchell mine at Adam Peak, about 32 km northeast of Golconda, in Humboldt County, Nevada, US. 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. [5] 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., US. [9]
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 shales, argillites (lithified muds and oozes) and limestones, near an intrusion of granodiorite.
Associated minerals are orpiment, realgar, stibnite, cinnabar and quartz, [5] as well as galkhaite, laffittite, chabournéite, christite, lorandite, marcasite, barite, fluorite and calcite. [4]
Getchellite is found at the type locality in Nevada, United States, and also in Azerbaijan, China, Iran, Japan, Kyrgyzstan and Russia. [3]
Getchellite has been synthesized from As3SbS6 glass in sodium sulfide solutions at 2600 C. and 1,000 bars pressure. [5]
Arsenopyrite is an iron arsenic sulfide (FeAsS). It is a hard metallic, opaque, steel grey to silver white mineral with a relatively high specific gravity of 6.1. When dissolved in nitric acid, it releases elemental sulfur. When arsenopyrite is heated, it produces sulfur and arsenic vapor. With 46% arsenic content, arsenopyrite, along with orpiment, is a principal ore of arsenic. When deposits of arsenopyrite become exposed to the atmosphere, the mineral slowly converts into iron arsenates. Arsenopyrite is generally an acid-consuming sulfide mineral, unlike iron pyrite which can lead to acid mine drainage.
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. The name is derived from the Greek στίβι stibi through the Latin stibium as the former name for the mineral and the element antimony.
Nickeline or niccolite is a mineral consisting primarily of nickel arsenide (NiAs). The naturally-occurring mineral contains roughly 43.9% nickel and 56.1% arsenic by mass, but composition of the mineral may vary slightly.
Realgar, also known as "ruby sulphur" or "ruby of arsenic", is an arsenic sulfide mineral with the chemical formula α-As4S4. 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 color, melts at 320 °C, and burns with a bluish flame releasing fumes of arsenic and sulfur. Realgar is soft with a Mohs hardness of 1.5 to 2 and has a specific gravity of 3.5. Its streak is orange colored. It is trimorphous with pararealgar and bonazziite. Its name comes from the Arabic rahj al-ġār, via Medieval Latin, and its earliest record in English is in the 1390s.
Ullmannite is a nickel antimony sulfide mineral with formula: NiSbS. Considerable substitution occurs with cobalt and iron in the nickel site along with bismuth and arsenic in the antimony site. A solid solution series exists with the high cobalt willyamite.
Orpiment is a deep-colored, orange-yellow arsenic sulfide mineral with formula As
2S
3. It is found in volcanic fumaroles, low-temperature hydrothermal veins, and hot springs and is formed both by sublimation and as a byproduct of the decay of another arsenic sulfide mineral, realgar. Orpiment takes its name from the Latin auripigmentum because of its deep-yellow color.
Claudetite is an arsenic oxide mineral with chemical formula As2O3. Claudetite is formed as an oxidation product of arsenic sulfides and is colorless or white. It can be associated with arsenolite (the cubic form of As2O3) as well as realgar (As4S4), orpiment (As2S3) and native sulfur.
Lorándite 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. Associated minerals include stibnite, realgar, orpiment, cinnabar, vrbaite, greigite, marcasite, pyrite, tetrahedrite, antimonian sphalerite, arsenic and barite.
Pararealgar is an arsenic sulfide mineral with the chemical formula As4S4, also represented as AsS. It forms gradually from realgar under exposure to light. Its name derives from the fact that its elemental composition is identical to realgar, As4S4. It is soft with a Mohs hardness of 1 - 1.5, is yellow orange in colour, and its monoclinic prismatic crystals are very brittle, easily crumbling to powder.
Gersdorffite is a nickel arsenic sulfide mineral with formula NiAsS. It crystallizes in the isometric system showing diploidal symmetry. It occurs as euhedral to massive opaque, metallic grey-black to silver white forms. Gersdorffite belongs to a solid solution series with cobaltite, CoAsS. Antimony freely substitutes also leading to ullmannite, NiSbS. It has a Mohs hardness of 5.5 and a specific gravity of 5.9 to 6.33.
The Getchell Mine is an underground gold mine in the Potosi Mining District of Humboldt County, Nevada, on the east flank of the Osgood Mountains, 35 miles northeast of Winnemucca. Prospectors Edward Knight and Emmet Chase discovered gold in 1933 and located the first claims in 1934. With the financial backing of Noble Getchell and George Wingfield, the Getchell Mine, Inc. was organized in 1936 and the mine was brought into production in 1938.
Alacránite (As8S9) is an arsenic sulfide mineral first discovered in the Uzon caldera, Kamchatka, Russia. It was named for its occurrence in the Alacrán silver/arsenic/antimony mine. Pampa Larga, Chile. It is generally more rare than realgar and orpiment. Its origin is hydrothermal. It occurs as subhedral to euhedral tabular orange to pale gray crystals that are transparent to translucent. It has a yellow-orange streak with a hardness of 1.5. It crystallizes in the monoclinic crystal system. It occurs with realgar and uzonite as flattened and prismatic grains up to 0.5 mm across.
Campigliaite is a copper and manganese sulfate mineral with a chemical formula of Cu4Mn(SO4)2(OH)6·4H2O. It has a chemical formula and also a crystal structure similar to niedermayrite, with Cd(II) cation replacing by Mn(II). The formation of campigliaite is related to the oxidation of sulfide minerals to form sulfate solutions with ilvaite associated with the presence of manganese. Campigliaite is a rare secondary mineral formed when metallic sulfide skarn deposits are oxidized. While there are several related associations, there is no abundant source for this mineral due to its rare process of formation. Based on its crystallographic data and chemical formula, campigliaite is placed in the devillite group and considered the manganese analogue of devillite. Campigliaite belongs to the copper oxysalt minerals as well followed by the subgroup M=M-T sheets. The infinite sheet structures that campigliaite has are characterized by strongly bonded polyhedral sheets, which are linked in the third dimension by weaker hydrogen bonds.
Allchar deposit is a low-temperature hydrothermal gold–arsenic–antimony–thallium deposit in Kavadarci Municipality of North Macedonia. For some time, the thallium-rich part of the deposit was mined. The Crven Dol mine yielded thallium and the ore body still holds estimated amount of 500 t of thallium. The mineral lorandite from this ore deposit can be used to determine the solar neutrino flux.
Wakabayashilite is a rare arsenic, antimony sulfide mineral with formula [(As,Sb)6S9][As4S5].
Sarabauite (sar-a-bau'-ite) is a red monoclinic sulfide mineral with the chemical formula: CaSb10O10S6.
Guettardite is a rare arsenic-antimony lead sulfosalt mineral with the chemical formula Pb(Sb,As)2S4. It forms gray black metallic prismatic to acicular crystals with monoclinic symmetry. It is a dimorph of the triclinic twinnite.
Stibarsen or allemontite is a natural form of arsenic antimonide (AsSb) or antimony arsenide (SbAs). The name stibarsen is derived from Latin stibium (antimony) and arsenic, whereas allemonite refers to the locality Allemont in France where the mineral was discovered. It is found in veins at Allemont, Isère, France; Valtellina, Italy; and the Comstock Lode, Nevada; and in a lithium pegmatites at Varuträsk, Sweden. Stibarsen is often mixed with pure arsenic or antimony, and the original description in 1941 proposed to use stibarsen for AsSb and allemontite for the mixtures. Since 1982, the International Mineralogical Association considers stibarsen as the correct mineral name.
Pearceite is one of the four so-called "ruby silvers", pearceite Cu(Ag,Cu)6Ag9As2S11, pyrargyrite Ag3SbS3, proustite Ag3AsS3 and miargyrite AgSbS2. It was discovered in 1896 and named after Dr Richard Pearce (1837–1927), a Cornish–American chemist and metallurgist from Denver, Colorado.
Hidalgoite, PbAl3(AsO4)(SO4)(OH)4, is a rare member of the beudantite group and is usually classified as part of the alunite family. It was named after the place where it was first discovered, the Zimapán mining district, Hidalgo, Mexico. At Hidalgo where it was initially discovered, it was found as dense white masses in alternating dikes of quartz latite and quartz monzonite alongside other secondary minerals such as sphalerite, arsenopyrite, cerussite and trace amounts of angelsite and alamosite, it was then rediscovered at other locations such as Australia where it occurs on oxidized shear zones above greywacke shales especially on the anticline prospects of the area, and on fine grained quartz-spessartine rocks in Broken Hill, Australia. Hidalgoite specimens are usually associated with copper minerals, clay minerals, iron oxides and polymetallic sulfides in occurrence.