Uraninite

Last updated
Uraninite
Pitchblende schlema-alberoda.JPG
Pitchblende from Niederschlema-Alberoda deposit, Germany
General
Category Oxide minerals
Formula
(repeating unit)
Uranium dioxide or uranium(IV) oxide (UO2)
IMA symbol Urn [1]
Strunz classification 4.DL.05
Crystal system Isometric
Crystal class Hexoctahedral (m3m)
H-M symbol: (4/m 3 2/m)
Space group Fm3m
Unit cell a = 5.4682 Å; Z = 4
Identification
ColorSteel-black to velvet-black, brownish black, pale gray to pale green; in transmitted light, pale green, pale yellow to deep brown and green-gray (thin fragments)
Crystal habit Massive, botryoidal, granular. Octahedral crystals uncommon.
Cleavage Indistinct
Fracture Conchoidal to uneven
Mohs scale hardness5–6
Luster Submetallic, greasy, dull
Streak Brownish black, gray, olive-green
Diaphaneity Opaque; transparent in thin fragments
Specific gravity 10.63–10.95; decreases on oxidation
Optical propertiesIsotropic
Other characteristics Radioactive.svg Radioactive 70 Bq/g to 150 kBq/g
References [2] [3] [4] [5]
Major varieties
PitchblendeMassive

Uraninite, also known as pitchblende, is a radioactive, uranium-rich mineral and ore with a chemical composition that is largely UO2 but because of oxidation typically contains variable proportions of U3O8. Radioactive decay of the uranium causes the mineral to contain oxides of lead and trace amounts of helium. It may also contain thorium and rare-earth elements. [2] [4]

Contents

Overview

Uraninite used to be known as pitchblende (from pitch , because of its black color, and blende, from blenden meaning "to deceive", a term used by German miners to denote minerals whose density suggested metal content, but whose exploitation, at the time they were named, was either unknown or not economically feasible). The mineral has been known since at least the 15th century, from silver mines in the Ore Mountains, on the German/Czech border. The type locality is the historic mining and spa town known as Joachimsthal, the modern-day Jáchymov, on the Czech side of the mountains, where F. E. Brückmann described the mineral in 1772. [4] [6] Pitchblende from the Johanngeorgenstadt deposit in Germany was used by M. Klaproth in 1789 to discover the element uranium. [7]

All uraninite minerals contain a small amount of radium as a radioactive decay product of uranium. Marie Curie used pitchblende, processing tons of it herself, as the source material for her isolation of radium in 1910. [8]

Uraninite also always contains small amounts of the lead isotopes 206Pb and 207Pb, the end products of the decay series of the uranium isotopes 238U and 235U respectively. Small amounts of helium are also present in uraninite as a result of alpha decay. Helium was first found on Earth in cleveite, an impure radioactive variety of uraninite, after having been discovered spectroscopically in the Sun's atmosphere. The extremely rare elements technetium and promethium can be found in uraninite in very small quantities (about 200  pg/kg and 4  fg/kg respectively), produced by the spontaneous fission of uranium-238. Francium can also be found in uraninite at 1 francium atom for every 1 × 1018 uranium atoms in the ore as a result from the decay of actinium.

Occurrence

Uraninite crystals from Topsham, Maine (size: 2.7 x 2.4 x 1.4 cm) Uraninite-usa32abg.jpg
Uraninite crystals from Topsham, Maine (size: 2.7 × 2.4 × 1.4 cm)

Uraninite is a major ore of uranium. Some of the highest-grade uranium ores in the world were found in the Shinkolobwe mine in the Democratic Republic of the Congo (the initial source for the Manhattan Project) and in the Athabasca Basin in northern Saskatchewan, Canada. Another important source of pitchblende is at Great Bear Lake in the Northwest Territories of Canada, where it is found in large quantities associated with silver. It also occurs in Australia, the Czech Republic, Germany, England, Rwanda, Namibia and South Africa. In the United States, it can be found in the states of Arizona, Colorado, Connecticut, Maine, New Hampshire, New Mexico, North Carolina and Wyoming. The geologist Charles Steen made a fortune on the production of uraninite in his Mi Vida mine in Moab, Utah. Uranium ores from the Ore Mountains (today the border between the Czech Republic and Germany) were an important supply of both the wartime German nuclear program (which failed to produce a bomb) and the Soviet nuclear program. Mining for uranium in the Ore Mountains (under the auspices of SDAG Wismut after the war) ceased after the collapse of the German Democratic Republic.

Uranium ore is generally processed close to the mine into yellowcake, which is an intermediate step in the processing of uranium.

See also

Related Research Articles

Francium is a chemical element; it has symbol Fr and atomic number 87. It is extremely radioactive; its most stable isotope, francium-223, has a half-life of only 22 minutes. It is the second-most electropositive element, behind only caesium, and is the second rarest naturally occurring element. Francium's isotopes decay quickly into astatine, radium, and radon. The electronic structure of a francium atom is [Rn] 7s1; thus, the element is classed as an alkali metal.

<span class="mw-page-title-main">Radium</span> Chemical element with atomic number 88 (Ra)

Radium is a chemical element; it has symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, but it readily reacts with nitrogen (rather than oxygen) upon exposure to air, forming a black surface layer of radium nitride (Ra3N2). All isotopes of radium are radioactive, the most stable isotope being radium-226 with a half-life of 1,600 years. When radium decays, it emits ionizing radiation as a by-product, which can excite fluorescent chemicals and cause radioluminescence. Of the radioactive elements that occur in quantity, radium is considered the most toxic.

<span class="mw-page-title-main">Uranium</span> Chemical element with atomic number 92 (U)

Uranium is a chemical element; it has symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium radioactively decays, usually by emitting an alpha particle. The half-life of this decay varies between 159,200 and 4.5 billion years for different isotopes, making them useful for dating the age of the Earth. The most common isotopes in natural uranium are uranium-238 and uranium-235. Uranium has the highest atomic weight of the primordially occurring elements. Its density is about 70% higher than that of lead and slightly lower than that of gold or tungsten. It occurs naturally in low concentrations of a few parts per million in soil, rock and water, and is commercially extracted from uranium-bearing minerals such as uraninite.

<span class="mw-page-title-main">Alkaline earth metal</span> Group of chemical elements

The alkaline earth metals are six chemical elements in group 2 of the periodic table. They are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). The elements have very similar properties: they are all shiny, silvery-white, somewhat reactive metals at standard temperature and pressure.

<span class="mw-page-title-main">Age of Earth</span> Scientific dating of the age of Earth

The age of Earth is estimated to be 4.54 ± 0.05 billion years (4.54 × 109 years ± 1%). This age may represent the age of Earth's accretion, or core formation, or of the material from which Earth formed. This dating is based on evidence from radiometric age-dating of meteorite material and is consistent with the radiometric ages of the oldest-known terrestrial material and lunar samples.

<span class="mw-page-title-main">Monazite</span> Mineral containing rare-earth elements

Monazite is a primarily reddish-brown phosphate mineral that contains rare-earth elements. Due to variability in composition, monazite is considered a group of minerals. The most common species of the group is monazite-(Ce), that is, the cerium-dominant member of the group. It occurs usually in small isolated crystals. It has a hardness of 5.0 to 5.5 on the Mohs scale of mineral hardness and is relatively dense, about 4.6 to 5.7 g/cm3. There are five different most common species of monazite, depending on the relative amounts of the rare earth elements in the mineral:

<span class="mw-page-title-main">Decay chain</span> Series of radioactive decays

In nuclear science, the decay chain refers to a series of radioactive decays of different radioactive decay products as a sequential series of transformations. It is also known as a "radioactive cascade". The typical radioisotope does not decay directly to a stable state, but rather it decays to another radioisotope. Thus there is usually a series of decays until the atom has become a stable isotope, meaning that the nucleus of the atom has reached a stable state.

A period 7 element is one of the chemical elements in the seventh row of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behavior of the elements as their atomic number increases: a new row is begun when chemical behavior begins to repeat, meaning that elements with similar behavior fall into the same vertical columns. The seventh period contains 32 elements, tied for the most with period 6, beginning with francium and ending with oganesson, the heaviest element currently discovered. As a rule, period 7 elements fill their 7s shells first, then their 5f, 6d, and 7p shells in that order, but there are exceptions, such as uranium.

<span class="mw-page-title-main">Zippeite</span>

Zippeite is a hydrous potassium uranium sulfate mineral with formula: K4(UO2)6(SO4)3(OH)10·4(H2O). It forms yellow to reddish brown monoclinic-prismatic crystals with perfect cleavage. The typical form is as encrustations and pulverulent earthy masses. It forms as efflorescent encrustations in underground uranium mines. It has a Mohs hardness of 2 and a specific gravity of 3.66. It is strongly fluorescent yellow under ultraviolet light and is moderately radioactive.

<span class="mw-page-title-main">Jáchymov</span> Town in Karlovy Vary, Czech Republic

Jáchymov is a spa town in Karlovy Vary District in the Karlovy Vary Region of the Czech Republic. It has about 2,400 inhabitants.

<span class="mw-page-title-main">Radioactive quackery</span> Quackery that improperly promotes radioactivity as a therapy for illnesses

Radioactive quackery is quackery that improperly promotes radioactivity as a therapy for illnesses. Unlike radiotherapy, which is the scientifically sound use of radiation for the destruction of cells, quackery pseudo-scientifically promotes involving radioactive substances as a method of healing for cells and tissues. It was most popular during the early 20th century, after the discovery in 1896 of radioactive decay. The practice has widely declined, but is still actively practiced by some.

<span class="mw-page-title-main">Thorianite</span>

Thorianite is a rare thorium oxide mineral, ThO2. It was originally described by Ananda Coomaraswamy in 1904 as uraninite, but recognized as a new species by Wyndham R. Dunstan. It was so named by Dunstan on account of its high percentage of thorium; it also contains the oxides of uranium, lanthanum, cerium, praseodymium and neodymium. Helium is present, and the mineral is slightly less radioactive than pitchblende, but is harder to shield due to its high energy gamma rays. It is common in the alluvial gem-gravels of Sri Lanka, where it occurs mostly as water worn, small, heavy, black, cubic crystals. The largest crystals are usually near 1.5 cm. Larger crystals, up to 6 cm (2.4 in), have been reported from Madagascar.

<span class="mw-page-title-main">Shinkolobwe</span> Former mine in the Democratic Republic of the Congo

Shinkolobwe, or Kasolo, or Chinkolobew, or Shainkolobwe, was a radium and uranium mine in the Haut-Katanga Province of the Democratic Republic of the Congo (DRC), located 20 km (12.4 mi) west of Likasi, 20 km (12.4 mi) south of Kambove, and about 145 km (90.1 mi) northwest of Lubumbashi.

<span class="mw-page-title-main">Uranium mining in Colorado</span>

Uranium mining in Colorado, United States, goes back to 1872, when pitchblende ore was taken from gold mines near Central City, Colorado. The Colorado uranium industry has seen booms and busts, but continues to this day. Not counting byproduct uranium from phosphate, Colorado is considered to have the third largest uranium reserves of any US state, behind Wyoming and New Mexico.

<span class="mw-page-title-main">Uranium ore</span> Economically recoverable concentrations of uranium within the Earths crust

Uranium ore deposits are economically recoverable concentrations of uranium within Earth's crust. Uranium is one of the most common elements in Earth's crust, being 40 times more common than silver and 500 times more common than gold. It can be found almost everywhere in rock, soil, rivers, and oceans. The challenge for commercial uranium extraction is to find those areas where the concentrations are adequate to form an economically viable deposit. The primary use for uranium obtained from mining is in fuel for nuclear reactors.

<span class="mw-page-title-main">Wismut (company)</span> Mining company in East Germany

SAG/SDAG Wismut was a uranium mining company in East Germany during the time of the Cold War. It produced a total of 230,400 tonnes of uranium between 1947 and 1990 and made East Germany the fourth largest producer of uranium ore in the world at the time. It was the largest single producer of uranium ore in the entire sphere of control of the USSR. In 1991 after German reunification it was transformed into the Wismut GmbH company, owned by the Federal Republic of Germany, which is now responsible for the restoration and environmental cleanup of the former mining and milling areas. The head office of SDAG Wismut / Wismut GmbH is in Chemnitz-Siegmar.

<span class="mw-page-title-main">Johannite</span>

Johannite is a rare uranium sulfate mineral. It crystallizes in the triclinic crystal system with the chemical composition Cu[UO2(OH)SO4]2·8H2O. It crystallizes in the triclinic system and develops only small prism or thin to thick tabular crystals, usually occurs as flaky or spheroidal aggregates and efflorescent coatings. Its color is emerald-green to apple-green and its streak is pale green.

<span class="mw-page-title-main">Adolf Patera</span>

Adolf Patera, was a Bohemian chemist, mineralogist and metallurgist, best known for the important role he played in the utilisation of uranium in colour production in glass, and associated with silver extraction from the mines at Joachimsthal, then part of the Austro-Hungarian Empire, now known as Jáchymov. Pateraite, supposedly a cobalt molybdate, is named after him.

<span class="mw-page-title-main">Nuclear transmutation</span> Conversion of an atom from one element to another

Nuclear transmutation is the conversion of one chemical element or an isotope into another chemical element. Nuclear transmutation occurs in any process where the number of protons or neutrons in the nucleus of an atom is changed.

<span class="mw-page-title-main">Curite</span>

Curite is a rare mineral with the chemical composition Pb3[(UO2)4|O4|(OH)3]2·2 H2O. It is therefore a hydrated lead uranyl oxide, which forms red needles or orange, massive aggregates.

References

  1. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi: 10.1180/mgm.2021.43 . S2CID   235729616.
  2. 1 2 Klein, Cornelis and Cornelius S. Hurlbut, Jr., Manual of Mineralogy, Wiley, 1985, 20th ed. pp. 307–308 ISBN   0-471-80580-7
  3. Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C. (eds.). "Uraninite". Handbook of Mineralogy (PDF). Vol. III (Halides, Hydroxides, Oxides). Chantilly, VA: Mineralogical Society of America. ISBN   0-9622097-2-4. Archived (PDF) from the original on March 14, 2012. Retrieved December 5, 2011.
  4. 1 2 3 Uraninite Archived November 10, 2012, at the Wayback Machine . Mindat.org
  5. Uraninite Archived October 21, 2011, at the Wayback Machine . Webmineral.com
  6. Veselovsky, F., Ondrus, P., Gabsová, A., Hlousek, J., Vlasimsky, P., Chernyshew, I. V. (January 2003). "Who was who in Jáchymov mineralogy II" (PDF). Journal of the Czech Geological Society . 48 (3–4): 193–205. Archived (PDF) from the original on April 23, 2014.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  7. Schüttmann, W. (1998). "Das Erzgebirge und sein Uran". RADIZ-Information. 16: 13–34.
  8. "Marie Curie and the Science of Radioactivity". history.aip.org. Archived from the original on June 28, 2017. Retrieved June 29, 2017.