Athabascaite
Encyclopedia
Athabascaite is a member of the copper
selenide mineral
s, and forms with other copper selenides. It was first discovered by S. Kaiman in 1949 while he was researching radioactive materials around Lake Athabasca
. Kaiman was conducting research near Uranium City, Saskatchewan
where mass amounts of uranium
mines were present.
, D.C. Harris decided to delve further into the virtually unknown mineral with little success.
(Se2–) serves as the anions, and the two are joined by ionic bonds. The crystal symmetry appears orthorhombic with the lattice parameters a = 8.227 ± 0.01, b = 11.982 ± 0.02, and c = 6.441 ± 0.01 Å. It has a calculated density
of 6.59 g/cm3; this density is identical to that of umangite
, and therefore the two are thought to have similar structure.
and stained carbonate
vein material as stringers and veinlets. When coupled with umangite, the mineral forms lath
-shaped slender and elongated grains averaging 20 by 50 micrometres. Athabascaite originally appeared as finer grained than the surrounding material, possessing a core of umangite. Because of the presence of umangite within the core, it is thought that the umangite may recrystallize
during the construction of athabascaite. Within the hematite, stained carbonate veins contain massive areas up to 300 micrometres in diameter. The veinlets are composed of a collection of arbitrarily organized crystals which rarely surpass 2 micrometres. These crystallites contain pure athabascaite phase.
The color of athabascaite is typically light gray, but can also be white, white-gray, and blue-gray. It has a hardness of approximately 2.50 on the Mohs scale. When exposed to polarized light, it displays a range of colors varying from creamy white to dark blue. The display of these distinct colors, along with its reflectivity
, allows athabascaite to be easily distinguished from other copper selenide minerals. It displays strong anisotropy and distinct birefringence
.
, Predborice, and Koksin Hill), France (Puy-de-Dôme
), Sweden (Kalmar
), Argentina (La Rioja Province
), and most recently Zaire
(Democratic Republic of Congo), all of which were found in or near uranium mines. In Canada, athabascaite is commonly associated with umangite, clausthalite
, eucairite, berzelianite, sulfatian berzelianite, klockmannite, eskebornite, tyrrellite
, copper, silver
, uraninite
, hematite, pyrite
, calcite
, barite
, quartz
and feldspar
. In Argentina and Sweden, it is associated with umangite and berzelianite. In the Czech Republic, it occurs with berzelianite, eucairite, crookesite
, tyrrellite
, ferroselite
, bukovite
, krutaite, calcite and dolomite
. In Zaire, it is associated with digenite
, berzelianite, yarrowite, spionkopite, trogtalite, native copper
and native gold.
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
selenide mineral
Selenide mineral
Selenide minerals are those minerals that have the selenide anion as a main component.Selenides are similar to sulfides and often grouped with them.Examples include:* athabascaite Cu5Se4* clausthalite PbSe* penroseite Se2* stilleite ZnSe...
s, and forms with other copper selenides. It was first discovered by S. Kaiman in 1949 while he was researching radioactive materials around Lake Athabasca
Lake Athabasca
Lake Athabasca is located in the northwest corner of Saskatchewan and the northeast corner of Alberta between 58° and 60° N.-History:The name in the Dene language originally referred only to the large delta formed by the confluence the Athabasca River at the southwest corner of the lake...
. Kaiman was conducting research near Uranium City, Saskatchewan
Uranium City, Saskatchewan
Uranium City is a settlement in northwestern Saskatchewan, Canada. It is on the northern shores of Lake Athabasca near the border of the Northwest Territories. It is above sea level. The settlement is northwest of Prince Albert, 760 km northeast of Edmonton and south of the Northwest...
where mass amounts of uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...
mines were present.
History
Kaiman sent his specimens for testing to J. W. Earley, then a graduate student. With the invention of the microprobe analyzerEnergy-dispersive X-ray spectroscopy
Energy-dispersive X-ray spectroscopy is an analytical technique used for the elemental analysis or chemical characterization of a sample. It relies on the investigation of an interaction of a some source of X-ray excitation and a sample...
, D.C. Harris decided to delve further into the virtually unknown mineral with little success.
Structure
Because of inavailability of sufficiently large single crystals, little is known about the atomic structure of athabascaite. Copper (Cu+) serves as the cations, seleniumSelenium
Selenium is a chemical element with atomic number 34, chemical symbol Se, and an atomic mass of 78.96. It is a nonmetal, whose properties are intermediate between those of adjacent chalcogen elements sulfur and tellurium...
(Se2–) serves as the anions, and the two are joined by ionic bonds. The crystal symmetry appears orthorhombic with the lattice parameters a = 8.227 ± 0.01, b = 11.982 ± 0.02, and c = 6.441 ± 0.01 Å. It has a calculated density
Density
The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...
of 6.59 g/cm3; this density is identical to that of umangite
Umangite
Umangite is a copper selenide mineral, Cu3Se2, discovered in 1891. It occurs only in small grains or fine granular aggregates with other copper minerals of the sulfide group. It has a hardness of 3. It is blue-black to red-violet in color with a black streak. It has a metallic luster.Umangite is...
, and therefore the two are thought to have similar structure.
Physical properties
Athabascaite often contains umangite as inclusionsInclusion (mineral)
In mineralogy, an inclusion is any material that is trapped inside a mineral during its formation.In gemology, an inclusion is a characteristic enclosed within a gemstone, or reaching its surface from the interior....
and stained carbonate
Carbonate
In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....
vein material as stringers and veinlets. When coupled with umangite, the mineral forms lath
Lath
A lath is a thin, narrow strip of some straight-grained wood or other material, including metal or gypsum. A lattice, or lattice-work, is a criss-crossed or interlaced arrangement of laths, or the pattern made by such an arrangement...
-shaped slender and elongated grains averaging 20 by 50 micrometres. Athabascaite originally appeared as finer grained than the surrounding material, possessing a core of umangite. Because of the presence of umangite within the core, it is thought that the umangite may recrystallize
Recrystallization (geology)
In geology, solid-state recrystallization is a metamorphic process that occurs under situations of intense temperature and pressure where grains, atoms or molecules of a rock or mineral are packed closer together, creating a new crystal structure. The basic composition remains the same...
during the construction of athabascaite. Within the hematite, stained carbonate veins contain massive areas up to 300 micrometres in diameter. The veinlets are composed of a collection of arbitrarily organized crystals which rarely surpass 2 micrometres. These crystallites contain pure athabascaite phase.
The color of athabascaite is typically light gray, but can also be white, white-gray, and blue-gray. It has a hardness of approximately 2.50 on the Mohs scale. When exposed to polarized light, it displays a range of colors varying from creamy white to dark blue. The display of these distinct colors, along with its reflectivity
Reflectivity
In optics and photometry, reflectivity is the fraction of incident radiation reflected by a surface. In general it must be treated as a directional property that is a function of the reflected direction, the incident direction, and the incident wavelength...
, allows athabascaite to be easily distinguished from other copper selenide minerals. It displays strong anisotropy and distinct birefringence
Birefringence
Birefringence, or double refraction, is the decomposition of a ray of light into two rays when it passes through certain anisotropic materials, such as crystals of calcite or boron nitride. The effect was first described by the Danish scientist Rasmus Bartholin in 1669, who saw it in calcite...
.
Geologic occurrence
After being discovered in Canada, a few other samples have been found in Czech Republic (PetrovicePetrovice
Petrovice may refer to several villages in the Czech Republic:* Petrovice - a village in Blansko District* Petrovice - a village in Bruntál District...
, Predborice, and Koksin Hill), France (Puy-de-Dôme
Puy-de-Dôme
Puy-de-Dôme is a department in the centre of France named after the famous dormant volcano, the Puy-de-Dôme.Inhabitants were called Puydedomois until December 2005...
), Sweden (Kalmar
Kalmar
Kalmar is a city in Småland in the south-east of Sweden, situated by the Baltic Sea. It had 62,767 inhabitants in 2010 and is the seat of Kalmar Municipality. It is also the capital of Kalmar County, which comprises 12 municipalities with a total of 233,776 inhabitants .From the thirteenth to the...
), Argentina (La Rioja Province
La Rioja Province (Argentina)
La Rioja is a one of the provinces of Argentina and is located in the west of the country. Neighboring provinces are from the north clockwise Catamarca, Córdoba, San Luis and San Juan.-History:...
), and most recently Zaire
Zaire
The Republic of Zaire was the name of the present Democratic Republic of the Congo between 27 October 1971 and 17 May 1997. The name of Zaire derives from the , itself an adaptation of the Kongo word nzere or nzadi, or "the river that swallows all rivers".-Self-proclaimed Father of the Nation:In...
(Democratic Republic of Congo), all of which were found in or near uranium mines. In Canada, athabascaite is commonly associated with umangite, clausthalite
Clausthalite
Clausthalite is a lead selenide mineral, PbSe. It forms a solid solution series with galena PbS.-Occurrence:It occurs in low-sulfur hydrothermal deposits with other selenides and in mercury deposits...
, eucairite, berzelianite, sulfatian berzelianite, klockmannite, eskebornite, tyrrellite
Tyrrellite
Tyrrellite is a selenide mineral that has a formula of Cu2Se4. It has been found in the Goldfields District in northern Saskatchewan, as well as in the Petrovice deposit, Czech Republic. It is named after the Canadian geologist Joseph Burr Tyrrell...
, copper, silver
Silver
Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal...
, uraninite
Uraninite
Uraninite is a radioactive, uranium-rich mineral and ore with a chemical composition that is largely UO2, but also contains UO3 and oxides of lead, thorium, and rare earth elements...
, hematite, pyrite
Pyrite
The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2. This mineral's metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool's gold because of its resemblance to gold...
, 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:...
, 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...
, 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,...
and feldspar
Feldspar
Feldspars are a group of rock-forming tectosilicate minerals which make up as much as 60% of the Earth's crust....
. In Argentina and Sweden, it is associated with umangite and berzelianite. In the Czech Republic, it occurs with berzelianite, eucairite, crookesite
Crookesite
Crookesite is a selenide mineral composed of copper and selenium with variable thallium and silver.-Characteristics:Its chemical formula is reported either as Cu7Se4 or 2Se...
, tyrrellite
Tyrrellite
Tyrrellite is a selenide mineral that has a formula of Cu2Se4. It has been found in the Goldfields District in northern Saskatchewan, as well as in the Petrovice deposit, Czech Republic. It is named after the Canadian geologist Joseph Burr Tyrrell...
, ferroselite
Ferroselite
Ferroselite is an iron selenide of general formula FeSe2 precipitated under reducing conditions in anoxic environments. It is a source of selenium in the Rocky Mountains where selenium occurrence is associated with Upper Cretaceous shale deposits....
, bukovite
Bukovite
Bukovite is a rare selenide mineral with formula Tl2Cu3FeSe4. It is a brown to black metallic mineral which crystallizes in the tetragonal system....
, krutaite, calcite and dolomite
Dolomite
Dolomite is a carbonate mineral composed of calcium magnesium carbonate CaMg2. The term is also used to describe the sedimentary carbonate rock dolostone....
. In Zaire, it is associated with digenite
Digenite
Digenite is a copper sulfide mineral with formula: Cu9S5. Digenite is a black to dark blue opaque mineral that crystallizes with a trigonal - hexagonal scalenohedral structure. In habit it is usually massive, but does often show pseudo-cubic forms. It has poor to indistinct cleavage and a brittle...
, berzelianite, yarrowite, spionkopite, trogtalite, native copper
Native copper
Copper, as native copper, is one of the few metallic elements to occur in uncombined form as a natural mineral, although most commonly occurs in oxidized states and mixed with other elements...
and native gold.