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Torbernite

Torbernite is a radioactive, secondary mineral belonging to the autunite group of uranyl phosphates, with the chemical formula Cu(UO₂)₂(PO₄)₂·12H₂O.^[1] It forms as vibrant emerald-green to apple-green tabular crystals or foliated masses in the oxidized zones of uraniferous copper deposits, often dehydrating to the related mineral metatorbernite under low-humidity conditions.^[2] Named after the Swedish chemist Torbern Olof Bergman (1735–1784), torbernite was first described in 1793 and serves as an important indicator of uranium mineralization due to its high uranium content, approximately 47% by weight.^[1] Torbernite crystallizes in the tetragonal system with space group P4/nnc, featuring a = 7.0267(4) Å and c = 20.807(2) Å.^[1] Its physical properties include a Mohs hardness of 2–2.5, perfect cleavage on {001}, and a specific gravity of 3.22, making it brittle and micaceous in texture.^[2] The mineral exhibits a vitreous to pearly luster, a pale green streak, and transparency that ranges from transparent to translucent.^[1] Optically, it is uniaxial negative with refractive indices nω = 1.590–1.592 and nε = 1.581–1.582, showing visible pleochroism from dark green to sky-blue.^[2] Torbernite forms through the supergene alteration of primary uranium minerals like uraninite in phosphate-rich, oxygenated groundwater environments within copper-uranium ore bodies.^[3] It is commonly associated with autunite, zeunerite, kasolite, and quartz, and occurs worldwide in localities such as Jáchymov in the Czech Republic, Schneeberg in Germany, Cornwall in England, and the Musonoi mine in the Democratic Republic of the Congo.^[1] Due to its radioactivity, torbernite requires careful handling and is not used commercially for uranium extraction, though it has historical significance in early uranium prospecting.^[3] In modern contexts, torbernite is primarily valued in mineral collections and geological research as a uranium ore indicator and for studies in radiation effects on mineral structures.^[2] Its sheet-like structure, composed of uranyl phosphate layers linked by copper cations and water molecules, exemplifies the autunite-type architecture common in many secondary uranium minerals.^[1]

Etymology and History

Naming Origin

Torbernite was formally named in 1793 by the German mineralogist Abraham Gottlob Werner.^[2] Werner bestowed the name to honor the Swedish chemist and mineralogist Torbern Olof Bergman (1735–1784), a prominent figure in 18th-century science whose work advanced the understanding of mineral chemistry.^[2] Bergman, born on March 20, 1735, in Katharinberg, Sweden, and who passed away on July 8, 1784, in Medevi, served as Professor of Chemistry, Pharmacy, and Mineralogy at Uppsala University.^[2] His key contributions included the publication of Sciagraphia Regni Mineralis (1779), a systematic classification of minerals based on chemical properties, as well as pioneering research in quantitative chemical analysis, the study of chemical affinities, and the characterization of elements like nickel and bismuth.^[2] These efforts established him as a foundational influence in mineralogy, making him a fitting honoree for a uranium-bearing phosphate mineral.^[2] The name "torbernite" derives linguistically from Bergman's first name, "Torbern," adapted to the standard mineralogical suffix "-ite," which denotes a distinct mineral species.^[2] Prior to this formal nomenclature, the mineral was described under earlier German terms such as "Kupfer-Uranit," reflecting its composition involving copper and uranium, as noted in 19th-century mineralogical literature.^[4]

Discovery and Early Research

Torbernite was first identified in the late 18th century from specimens collected at the Georg Wagsfort Mine near Johanngeorgenstadt in the Ore Mountains of Saxony, Germany.^[5] It was first mentioned in 1772 by Ignaz von Born in his work Lythophylacium Bornianum, calling it "mica viridis crystallina" (green crystalline mica).^[6] In 1780, Abraham Gottlob Werner described the mineral in more detail as "grüner Glimmer" (green mica).^[6] In 1789, German chemist Martin Heinrich Klaproth analyzed a sample of this green, mica-like mineral at his laboratory in Berlin's Apotheke zum Bären, isolating a new element he named uranium after the recently discovered planet Uranus; he initially termed the mineral "Grüner Uranglimmer" (green uranium mica) based on its composition.^[7] This analysis marked the initial recognition of torbernite's uranium content, though it was initially viewed as a secondary alteration product of primary uranium ores like pitchblende.^[5] Early studies encountered confusion with other green uranium-bearing minerals, such as uranite and members of the autunite group, due to similar appearances and associations in oxidized zones of copper-uranium deposits; these distinctions were not fully resolved until later classifications.^[2] In 1793, Abraham Gottlob Werner, director of the Mining Academy in Freiberg, Saxony, formally named the mineral torbernite in honor of Swedish chemist Torbern Olof Bergman, acknowledging Bergman's foundational contributions to mineral chemistry.^[2] Throughout the 19th century, further analyses solidified torbernite's identity as a distinct species amid growing European uranium prospecting, particularly in Saxony's silver-copper mines. These efforts established torbernite as a key indicator mineral in uranium exploration, though its full structural details awaited later advancements.^[7]

Classification and Composition

Mineral Classification

Torbernite is classified as a phosphate mineral within the autunite group of the uranyl phosphate subclass, according to the Strunz classification system under category 08.EB (uranyl phosphates and arsenates).^[8]^[2] This placement reflects its layered structure composed of uranyl phosphate sheets, characteristic of the autunite group minerals.^[9] The International Mineralogical Association (IMA) recognizes torbernite as a valid mineral species under the grandfather clause, as it was described and approved prior to 1959.^[2] This status confirms its established role in mineral taxonomy without requiring subsequent validation.^[8] Torbernite is closely related to its arsenate analog, zeunerite, where the phosphate ions are substituted by arsenate, resulting in similar crystal structures and occurrences but distinct chemical compositions.^[10]^[9] Unlike primary uranium minerals such as uraninite, torbernite forms as a secondary phosphate through supergene alteration processes in oxidized zones of uranium-bearing deposits.^[2]

Chemical Formula and Variations

Torbernite is a hydrated copper uranyl phosphate mineral with the ideal chemical formula Cu(UO₂)₂(PO₄)₂ · 12 H₂O.^[1] This end-member composition corresponds to the following elemental percentages by weight: copper 6.29%, uranium 47.15%, phosphorus 6.14%, oxygen 38.05%, and hydrogen 2.38%.^[2] However, the mineral commonly exhibits variability in its hydration state, with the number of water molecules ranging from 8 to 12 per formula unit, often expressed as Cu(UO₂)₂(PO₄)₂ · nH₂O where n = 8–12; specimens typically contain 10–12 water molecules depending on environmental conditions such as relative humidity.^[2]^[9] Dehydration to the 8 H₂O variant results in metatorbernite, but intermediate hydration levels are frequently observed in natural samples.^[1] In natural occurrences, torbernite may incorporate minor impurities, including substitutions of Fe²⁺ or other divalent metals (such as Ni²⁺ or Co²⁺) for Cu²⁺ in the interlayer cation site, which can slightly alter the unit cell parameters without fundamentally changing the structure.^[3]^[11] Torbernite belongs to the autunite group, sharing structural similarities with other uranyl phosphates.^[9]

Crystal Structure

Symmetry and Unit Cell

Torbernite crystallizes in the tetragonal crystal system, characterized by a high degree of symmetry that reflects its layered uranyl phosphate architecture.^[12] The space group is P4/nnc (No. 126), which accommodates the mineral's pseudo-symmetric arrangement of uranyl ions, phosphate tetrahedra, and interlayer copper-water complexes.^[12]^[1] The unit cell parameters for the fully hydrated form, Cu[(UO₂)(PO₄)]₂(H₂O)₁₂, are a = 7.0267(4) Å and c = 20.807(2) Å, with a unit cell volume of 1027.3(1) Å³ and Z = 2 formula units per cell.^[12] These dimensions arise from the stacking of uranyl phosphate sheets along the c-axis, separated by hydrated copper layers.^[12] The calculated density, based on the unit cell volume and the formula for the dodecahydrate, is 3.264(1) g/cm³.^[12] This value aligns with measured densities around 3.22 g/cm³, confirming the structural model's accuracy for the hydrated phase.^[2]^[1]

Structural Layers and Bonding

Torbernite possesses a layered crystal structure characterized by sheets of uranyl phosphate composition [(UO₂)(PO₄)]⁻ that lie parallel to the (001) plane. These sheets are formed by the polymerization of uranyl (UO₂²⁺) cations and phosphate (PO₄³⁻) anions, where the uranyl ions adopt square bipyramidal coordination with two axial oxygen atoms and four equatorial oxygen atoms shared with the phosphate tetrahedra.^[9] The phosphorus atoms within the sheets are tetrahedrally coordinated by four oxygen atoms, contributing to the overall rigidity of the layer through vertex-sharing with the uranyl polyhedra.^[9] In the interlayer regions, copper (Cu²⁺) cations occupy distorted octahedral sites, coordinated by four short bonds to water molecules and two longer bonds to oxygen atoms from the uranyl groups, approximating Cu(H₂O)₆ octahedra.^[9] The bonding between these uranyl phosphate sheets and the interlayer copper-water complexes is primarily weak, involving hydrogen bonds from the coordinated and interstitial water molecules to the sheet oxygens, as well as van der Waals interactions that maintain the overall stacking.^[13]^[14] Dehydration of torbernite results in the loss of four water molecules per formula unit, transforming it into metatorbernite and causing a contraction along the c-axis by approximately 16% due to the removal of interstitial water and reconfiguration of hydrogen bonding networks in the interlayer space.^[9] This process alters the sheet stacking arrangement while preserving the fundamental uranyl phosphate layer topology.^[9]

Physical Properties

Crystal Morphology

Torbernite crystals typically exhibit a tabular or platy habit, appearing as thin to thick tablets flattened parallel to the {001} face, often with square or rectangular outlines that may appear octagonal due to the development of prism faces.^[2]^[15] These crystals are influenced by the tetragonal crystal system.^[2] The dominant crystal forms include the basal pinacoid {001}, prisms {110}, and pyramids {011}, with {013} pyramids occasionally modifying edges; more complex forms like {111} pyramids are rare.^[2]^[15] Lateral faces are frequently striated or serrated, contributing to a rough or dull appearance.^[15] Twinning in torbernite is rare and occurs as contact or penetration twins on {110}, sometimes producing re-entrant angles.^[2]^[16] In massive occurrences, torbernite commonly forms aggregates such as foliated, micaceous, or scaly masses, including subparallel, fan-like, sheaf-like, or lamellar groups, as well as crusts and coatings.^[2]^[15]

Density, Hardness, and Cleavage

Torbernite exhibits a Mohs hardness of 2 to 2.5, rendering it a soft mineral that can be easily scratched by a fingernail or copper coin.^[1]^[2] This low hardness reflects its layered structure, which contributes to its fragility in bulk form.^[17] The specific gravity of torbernite is measured at 3.22 g/cm³ (calculated 3.264 g/cm³), with values varying slightly based on the degree of hydration, as the mineral's water content fluctuates with environmental humidity.^[1]^[17]^[18] Less hydrated specimens approach higher densities, while fully hydrated forms are lower.^[2] Cleavage in torbernite is perfect on the {001} plane, yielding thin, micaceous sheets that resemble those of mica minerals, while fracture is uneven.^[1]^[2] This prominent basal cleavage facilitates the mineral's separation into flexible lamellae, aiding identification in hand samples.^[17] In terms of tenacity, torbernite is brittle, though thin plates produced by cleavage may exhibit some flexibility.^[17]^[1] The tabular crystal habit further accentuates this behavior, allowing sheets to bend without breaking.^[2]

Optical and Chemical Properties

Color, Luster, and Optical Characteristics

Torbernite displays a distinctive green coloration ranging from emerald-green to grass-green, with variations including leek-green, siskin-green, and apple-green.^[1] This vibrant hue arises from its copper content and uranyl phosphate structure, though the color may darken or fade to a duller tone upon dehydration as it transforms into metatorbernite.^[3] The streak is pale green, providing a subtle indicator of its composition under testing.^[1] The mineral's luster is vitreous to subadamantine, often appearing waxy, and it takes on a pearly sheen on cleavage surfaces.^[1] This luster can diminish to dull upon exposure to air, coinciding with loss of hydration. Torbernite is transparent to translucent, allowing light to pass through fresh crystals while thicker or altered specimens appear more opaque.^[1] These optical traits contribute to its aesthetic appeal in mineral collections, though dehydration effects can alter transparency over time. Optically, torbernite is uniaxial negative, consistent with its tetragonal crystal system.^[1] The refractive indices are nω = 1.590–1.592 and nε = 1.581–1.582, yielding a birefringence of δ = 0.009–0.010.^[1] Pleochroism is visible and notable, with the ordinary ray (O) appearing dark green to sky-blue and the extraordinary ray (E) showing green; this color shift under polarized light highlights the mineral's anisotropic nature.^[1] Torbernite typically exhibits no fluorescence under ultraviolet light, though epitaxial intergrowths with other uranyl micas may fluoresce, distinguishing it from some other uranium-bearing minerals.^[2]

Stability, Solubility, and Reactivity

Torbernite exhibits limited stability under ambient conditions, readily undergoing dehydration in air to form metatorbernite by losing four water molecules from its formula unit of Cu(UO₂)₂(PO₄)₂·12H₂O.^[9] This transformation occurs even at room temperature and is accelerated under low or varying humidity, rendering torbernite prone to alteration during storage or transport. In high-humidity environments, the mineral is more stable, and partial rehydration can occur if previously dehydrated.^[2] Upon dehydration, torbernite often alters to a paler green hue.^[19] The solubility of torbernite is low in neutral water, with gradual leaching of uranium primarily as uranyl ions under prolonged exposure, contributing to trace mobilization in aqueous systems.^[20] Solubility increases significantly in dilute acids, such as hydrochloric acid (HCl), where protonation facilitates the release of uranium and phosphate components.^[11] This acid-enhanced dissolution underscores torbernite's role in uranium transport within acidic leachates or waste environments. Torbernite displays slow oxidation under atmospheric conditions, as its uranium is already in the hexavalent (U(VI)) state, limiting further redox reactivity.^[21] Uranium release is primarily driven by dissolution in acidic groundwater, where pH below 6 promotes breakdown and mobilization of uranyl species. The mineral shows no significant reactivity with bases, maintaining low solubility and structural integrity in alkaline media due to the stability of its uranyl phosphate framework at higher pH.^[20] Torbernite precipitation and stability are pH-dependent, favoring formation in mildly acidic to neutral conditions (pH 4–7) within oxidizing environments that support uranyl ion availability.^[11] At circumneutral pH under oxidizing potentials, solubility minima enhance its persistence as a secondary mineral phase.^[21]

Metatorbernite

Metatorbernite is the principal alteration product of torbernite, recognized as a distinct mineral species within the meta-autunite group due to its dehydrated nature and structural differences. Named in 1916, its chemical formula is Cu(UO₂)₂(PO₄)₂ · 8 H₂O, reflecting lower water content compared to the more hydrated torbernite.^[22] Physically, metatorbernite differs from torbernite in several key ways, including a paler green coloration, greater brittleness, and a contraction of the c-axis by approximately 17%, resulting from the loss of water molecules and closer packing of uranyl phosphate layers. These changes alter its optical properties, with refractive indices typically ranging from ω = 1.618–1.631 and ε = 1.622–1.628, and a vitreous to pearly luster.^[23] Metatorbernite forms through the natural dehydration of torbernite in arid conditions, where exposure to low humidity causes progressive loss of water, or via laboratory drying methods such as heating above 75°C.^[23] This process is often reversible under high humidity environments, allowing rehydration to torbernite when water activity increases, though the transformation may depend on temperature and relative humidity levels (e.g., slopes of ~0.8°C per 1% change in relative humidity).^[24] The resulting pseudomorphs preserve the tabular crystal habit of torbernite but exhibit reduced basal spacing, from ~10.4 Å per layer in torbernite to ~8.65 Å in metatorbernite.

Other Autunite Group Members

The autunite group consists of layered uranyl phosphate and arsenate minerals characterized by autunite-type sheets composed of uranyl cations [(UO₂)²⁺] linked to phosphate or arsenate tetrahedra [XO₄]³⁻ (X = P or As), forming anionic sheets of composition [(UO₂)(XO₄)]⁻ through the sharing of equatorial vertices of uranyl square bipyramids and oxygen atoms of the tetrahedra; these sheets are interleaved with layers containing divalent cations and water molecules.^[9]^[25] The interlayer cations, such as Ca²⁺ or Cu²⁺, balance the charge and coordinate with water molecules, resulting in tetragonal or pseudo-tetragonal symmetry and a flaky, tabular crystal habit common to the group. Autunite, the calcium end-member, has the formula Ca(UO₂)₂(PO₄)₂·10–12 H₂O and typically appears as bright yellow to yellow-green tabular crystals that exhibit strong fluorescence under ultraviolet light due to the uranyl ion. It serves as the phosphate analog to torbernite, which is the copper phosphate prototype of the group.^[9] Zeunerite represents the arsenate substitution variant with the formula Cu(UO₂)₂(AsO₄)₂·10–12 H₂O, featuring the same sheet structure as autunite but with arsenate tetrahedra instead of phosphate, leading to minor differences in unit cell dimensions and optical properties.^[9] It occurs in green to dark green crystals, often as a secondary mineral in uranium-bearing deposits.^[26] Meta-autunite is the dehydrated form of autunite, with a variable formula Ca(UO₂)₂(PO₄)₂·2–8 H₂O, formed through loss of interlayer water that causes sheet puckering and a transition to lower symmetry, while retaining the core uranyl phosphate framework.^[27] This dehydration product maintains the yellow coloration and fluorescence of its parent mineral but is less stable under humid conditions.^[28]

Occurrence and Formation

Geological Formation Processes

Torbernite is a secondary mineral that forms through the oxidation of primary uranium minerals, such as uraninite (UO₂) and coffinite (USiO₄), in near-surface environments.^[15] This process involves the weathering of these primary minerals, where uranium is mobilized as the uranyl ion (UO₂²⁺) by descending meteoric waters in oxidizing conditions.^[15] The mineral precipitates via supergene enrichment in phosphate-rich waters that circulate through fractured host rocks under acidic to near-neutral conditions, which favors the solubility of uranyl species while allowing their eventual combination with copper ions.^[15] In copper-bearing systems, torbernite commonly occurs with autunite, requiring the presence of Cu²⁺, UO₂²⁺, and PO₄³⁻ in solution for its crystallization as hydrated sheets. The source of phosphate ions is often derived from the dissolution of primary minerals like apatite in surrounding rocks or from organic phosphorus, though it remains unclear in many deposits.^[15] These ions derive from the dissolution of primary minerals and surrounding country rocks, leading to torbernite's deposition as green coatings or crystals in veins and fractures.^[15] Formation occurs at low temperatures in shallow supergene zones where evaporation and ion concentration promote precipitation.^[15] Torbernite is commonly associated with granitic pegmatites or hydrothermal uranium deposits that provide the initial primary mineralization subject to later oxidation.^[15]

Associated Minerals and Environments

Torbernite commonly forms in paragenetic association with other secondary uranyl phosphate minerals, including autunite, meta-autunite, saléeite, and uranophane, as observed in oxidized granite-hosted deposits where these minerals precipitate sequentially from oxidizing groundwater interacting with primary uranium sources like uraninite.^[29] It also co-occurs with accessory phases such as limonite, hydrous iron oxides, kaolinite, and quartz, which stabilize in similar supergene conditions.^[29]^[30] The mineral is primarily hosted in the oxidized zones of granitic intrusions, including fractionated granites and associated pegmatites, where it develops through weathering of primary uranium minerals along joints and cavities.^[31] Torbernite further appears in hydrothermal vein systems, often within sulfide-quartz veins cutting Precambrian crystalline rocks, and in sedimentary uranium deposits embedded in Neogene fluvial sediments like sandstones and claystones.^[29]^[30] In terms of zonal distribution, torbernite is concentrated in the upper profiles of oxidation zones, typically extending to depths of up to 150 feet, where it manifests as thin coatings on fractures or disseminations in altered wallrocks near veins.^[29] Rarely, torbernite associates with secondary copper minerals such as malachite and azurite in oxidized copper-uranium ores within granites and mafic dikes, reflecting localized supergene enrichment in polymetallic settings.^[32]

Notable Localities

Type and Historical Sites

Torbernite lacks a formally designated type locality according to the International Mineralogical Association, but the mineral's initial scientific description and naming are tied to specimens collected from the Georg Wagsfort Mine near Johanngeorgenstadt in the Ore Mountains of Saxony, Germany, around 1793.^[2] These early samples formed the basis for Abraham Gottlob Werner's recognition of the species, whom he described as a distinct green copper-uranyl phosphate mineral.^[2] Werner named torbernite in 1793 to honor the Swedish chemist and mineralogist Torbern Olof Bergman (1735–1784), whose analytical work on minerals influenced European mineralogy; this naming occurred shortly after Bergman's death and reflected the era's tradition of commemorating key figures in the field.^[2] Concurrently, German chemist Martin Heinrich Klaproth conducted chemical analyses on similar specimens from Saxon uranium-bearing deposits, identifying uranium as a new element in 1789 within what he termed "grüner Uranglimmer" (green uranium mica), a description that aligned closely with torbernite's composition and confirmed its uraniferous nature.^[33] Klaproth's work on these Johanngeorgenstadt samples marked one of the earliest detailed chemical characterizations of a uranium mineral, linking the site directly to foundational advancements in geochemistry. In the 19th century, significant historical collections of torbernite emerged from oxidized zones in Cornish mining districts, England, including specimens from the Old Gunnislake Mine and other uranium-enriched veins in the region, which were documented in early British mineralogical handbooks and contributed to comparative studies of European uranium phosphates.^[34] These Cornish examples, often exhibiting tabular green crystals, were prized in collections for their aesthetic and scientific value, underscoring torbernite's role in 19th-century explorations of secondary uranium mineralization.^[35]

Major Global Deposits

Torbernite occurs primarily as a secondary mineral in the oxidized zones of uranium-copper deposits, where it is generally uncommon and rare in large quantities, though exceptional specimens with well-formed tabular crystals have been recovered from select sites.^[2]^[36] The Democratic Republic of the Congo hosts some of the world's premier torbernite deposits in the Katanga province, particularly at the Shinkolobwe and Musonoi mines, yielding large, vibrant green crystals up to several centimeters across from uranium-rich veins.^[37]^[38] In North America, significant occurrences are documented in the Front Range of Colorado, USA, including areas near Pikes Peak, where torbernite coats fractures in Precambrian granites and pegmatites within uranium-bearing lodes.^[39] European deposits include the Margnac uranium mine in Haute-Vienne, France, a key site for phosphate-rich secondary uranium minerals like torbernite, which forms disseminated coatings in altered granites.^[40] In the Czech Republic, the Krásno ore district near Horní Slavkov features torbernite in Sn-W greisen deposits, associated with oxidized uranium accumulations in the Huber and Schnöd stocks.^[41] Torbernite is often found alongside autunite in these environments.^[2] More recent collections of torbernite have come from Australia's Radium Hill area in South Australia, where post-2000 explorations of historic tailings and outcrops have yielded specimens from the former uranium mine's secondary phosphate zones.^[42] Overall, the finest collector-grade material derives from these secondary uranium-copper settings, emphasizing the mineral's scarcity beyond trace occurrences.^[39]

Uses and Safety

Industrial and Scientific Uses

Torbernite is not a primary target for commercial uranium extraction due to its secondary nature and relatively low uranium content compared to primary ores like uraninite.^[43] However, it can serve as an indicator of uranium deposits and may be processed incidentally in some low-grade uraniferous copper ores using general acid leaching methods, such as sulfuric acid treatment.^[44] In scientific research, torbernite is utilized as a reference material for studying uranyl phosphate complexes through spectroscopic techniques, particularly near-infrared (NIR) and Raman spectroscopy, which reveal details about its hydration states and vibrational modes.^[45] These analyses help characterize the mineral's structure and aid in identifying similar uranium-bearing phases in environmental samples. Additionally, torbernite supports geochronological studies via U-Pb dating of secondary uranium minerals, providing insights into the timing of mineralization events in deposits, as demonstrated by isotopic analyses yielding ages such as 4.55 ± 0.02 Ma in specific localities.^[46] Torbernite holds value among mineral collectors for its vibrant green, tabular crystals, which are prized for display in cabinets due to their aesthetic appeal and rarity.^[43] Due to its radioactivity, torbernite has no applications as a gemstone or in non-uranium industrial processes.^[43]

Radioactivity Hazards and Precautions

Torbernite exhibits radioactivity primarily due to its uranium content, derived from the U-238 decay chain, where it acts as an alpha emitter. The mineral's specific activity is approximately 86,000 Bq/g in secular equilibrium, reflecting the total activity from its roughly 47% uranium composition and decay daughters, with gamma emissions being negligible compared to alpha particles.^[2] The main health risks associated with torbernite stem from internal exposure via inhalation or ingestion of fine dust particles, which can deliver alpha radiation directly to lung tissue or the gastrointestinal tract, potentially causing long-term cellular damage and increased cancer risk. External exposure to beta particles may irritate skin or eyes upon prolonged contact, while low-level gamma radiation poses a cumulative but lesser threat to surrounding tissues; children and pregnant individuals face heightened vulnerability due to greater sensitivity.^[47] Safety precautions for handling torbernite include storing specimens in sealed, labeled containers to contain dust and minimize radon gas buildup, wearing protective gloves and respiratory masks, and ensuring adequate ventilation during examination or preparation. Exposure should be limited to below 1 mSv per year for non-occupational handlers such as collectors, using principles of time, distance, and shielding—such as acrylic barriers for beta radiation—to reduce dose rates. Upon disposal, torbernite must be treated as radioactive waste following local environmental regulations to prevent environmental contamination.^[47] Torbernite is categorized as naturally occurring radioactive material (NORM) under international standards, subjecting it to regulatory oversight for safe management. The International Atomic Energy Agency (IAEA) provides guidelines emphasizing radiation protection through justification, optimization (keeping doses as low as reasonably achievable), and dose limits, with public exposure not exceeding 1 mSv annually from controlled sources.

References

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Occurrence: An uncommon secondary mineral formed in the oxidized zone of some uraniferous copper deposits. Association: Metatorbernite, autunite, zeunerite, ...Missing: composition | Show results with:composition
[2]
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A secondary mineral found in the oxidized zones of some uraniferous copper deposits. Often dehydrated to metatorbernite.
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Feb 20, 2024 · Torbernite is a mineral belonging to the uranyl phosphate group. Its chemical formula is (Cu,U)2(PO4)2·8-12H2O. It typically forms bright green to emerald- ...
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Aug 19, 2025 · Kupfer-Uranit mineral data, information about Kupfer-Uranit, its properties and worldwide locations.
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### Summary of Klaproth's Work with Torbernite, Discovery of Uranium, and Early History of the Mineral
[6]
https://www.strahlen.org/tw/typloc/torbernit.html
[7]
Chapter 9. Radioactivity - GeoScienceWorld
The nature of the samples, pitchblende with torbernite, was confirmed by chemical analysis, and mining by open-pit began in 1921. The richest ore was ...
[8]
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Secondary mineral in granites, and other uranium-bearing rocks. Help on IMA Status: IMA Status: Valid Species (Pre-IMA) 1793. Help on Locality: Locality ...
[9]
[PDF] TORBERNITE, ZEUNERITE - RRuff
These minerals contain the autunite-type sheet, of composition [(UO2)(PO4)]–, which involves the sharing of equatorial vertices of uranyl square bipyramids with ...
[10]
ZEUNERITE (Hydrated Copper Uranyl Arsenate)
Zeunerite is a rare uranyl arsenate that is similar to the more well known uranyl phosphate mineral torbernite. The two minerals are almost identical and share ...
[11]
[PDF] Solubility properties of synthetic and natural meta-torbernite - Vitorge
Sep 2, 2013 · They were probably incorporated by direct substitution for copper in the meta-torbernite structure, without affecting the structure of the ...
[12]
CRYSTAL STRUCTURES AND SYNTHESIS OF THE COPPER ...
Apr 1, 2003 · Torbernite is tetragonal, space group P4/nnc, a 7.0267(4), c 20.807(2) Å, V 1027.3(1) Å3, Z = 2, Dcalc 3.264(1) g/cm3. Zeunerite is ...
[13]
(PDF) Mineralogy and crystallography of uranium - ResearchGate
The two parts of the structure are held. together by weak bonding interactions, which may. include also Van der Waals and hydrogen bonds. The structure is ...
[14]
[PDF] Investigation of Metatorbernite Phase Relations in ... - JScholarship
Metatorbernite [Cu(UO2)2(PO4)2 • 8H2O] forms as a result of the alteration process of torbernite undergoing dehydration. ... (001) basal cleavage plane by van der ...
[15]
[PDF] Systematic Mineralogy Of Uranium And Thorium
Torbernite. A ... Peligot in 1841 to be in fact the oxide, U02 • Peligot then pre- pared the first elemental uranium by reducing UC14 with potassium.<|control11|><|separator|>
[16]
[PDF] Torbernite Cu(UO2)2(PO4)2 • 8−12H2O - RRuff
Crystal Data: Tetragonal. Point Group: 4/m 2/m 2/m. Thin to thick tabular ... Twinning: Rare on {110}. Physical Properties: Cleavage: Perfect on {001} ...
[17]
[PDF] Identification and Occurrence of Uranium and Vanadium Minerals ...
Cleavage: {001) perfect, {100} indistinct. Not brittle. Hardness: 2 1%. Specific gravity: 3.1 3.2, varying with the water content.
[18]
[PDF] A Prospector's guide to URANIUM deposits In Newfoundland and ...
Torbernite ... It has a bright emerald green color, a pearly luster, hardness of 2-2.5 (about the same as a fingernail), and specific gravity of about 3.5 (a ...
[19]
Locating hydrogen positions in the autunite mineral metatorbernite ...
There are several studies that report the structure of metatorbernite. Two different space groups have been suggested, P4/n and P4/nmm, with varying c parameter ...
[20]
Dehydration processes in the meta-autunite group minerals meta ...
Mar 2, 2017 · Metatorbernite has a dehydrated phase with a distinct peak at 8.07 Å at 100 °C (Fig. 4c 4). The DTA curve shows an endothermic peak at 86 °C ...
[21]
Meta-torbernite I, its physical properties and relation to Torbernite
Mar 14, 2018 · ... meta-torbernite I (meta-kupferuranit), was dependent on the temperature and the vapour-pressure, and that the boundary, of the stability ...
[22]
Solubility properties of synthetic and natural meta-torbernite
Aug 6, 2025 · Uranyl phosphates, such as metatorbernite, are known for their low solubility at circumneutral pH and are considered important for the control ...
[23]
Cu-Fe-U phosphate mineralization of the Hagendorf-Pleystein ...
9b favoured the evolution of torbernite under oxidizing conditions. Depending on the concentrations of Mn, Fe, Ca and Cu in the meteoric fluids, a solid ...
[24]
[PDF] Metatorbernite Cu(UO2)2(PO4)2 • 8H2O - RRuff
Cell Data: Space Group: P4/n. a = 6.969–6.972 c = 17.277–17.306. Z = 2. X-ray ... Sklavounos (1993). Refinement of the crystal structure of metatorbernite.
[25]
https://rruff.geo.arizona.edu/doclib/cm/vol42/CM42_1699.pdf
[26]
[PDF] The New IMA List of Minerals – A Work in Progress – Updated
... 1980-092 USA. Oxidation mineralogy of base metal deposits. MSA, Tucson (1983) ... Metatorbernite. Cu(UO2)2(PO4)2·8H2O. G. 1916. United Kingdom Mineralogical ...
[27]
synchrotron xrd investigation of temperature– a h2o –time resolved ...
Reactions for both metatorbernite-to-8.3Å phase and 8.3Å phase-to-6.9Å phase can be reversibly driven by temperature or aH2O changes.
[28]
[PDF] The Canadian Mineralogist Vol. 42, pp. 1699-1718 (2004)
The structure of autunite sensu stricto, Ca[(UO2)(PO4)]2(H2O)11, recently has been de- termined (Locock & Burns 2003a). The interlayer re- gion contains cations ...
[29]
Studies of uranium minerals (VII): Zeunerite* | American Mineralogist ...
Study of synthetic zeunerite indicated the existence of two and possibly three hydrates, one with 16 to 10H2O, one with 8 to 5H2O, and possibly a still lower ...
[30]
[PDF] Dehydration processes in the meta-autunite group minerals meta ...
Meta-autunite, metasaléeite, and metatorbernite decreased their basal spacings by losing water molecules. Comparison of the TG/DTA and XRD results indicates ...
[31]
MONOVALENT CATIONS IN STRUCTURES OF THE META ...
Mar 9, 2017 · The autunite and meta-autunite groups comprise one of the two major divisions of uranyl phosphate and uranyl arsenate minerals (the ...
[32]
[PDF] Geology of Uranium and Associated Ore Deposits Central Part of the ...
Paragenesis of vein minerals. _. Wallrock ... 'l'he most abundant secondary minerals are torbernite, autunite, and kasoli ...
[33]
https://digital.library.unt.edu/ark:/67531/metadc111225/m1/2/
[34]
[PDF] torbernite occurrence at the robineau claims, clear creek county ...
Bright green scales of torbernite also occur as coatings on fracture walls and seem to be closely associated with brov/n and black iron oxide stains. An ...
[35]
[PDF] * Radioactive Deposits in New Mexico
In the radioactive copper deposits uranium minerals are rarely visible ... copper minerals, such as chalcocite, malachite, azurite, and chrysocolla. At ...
[36]
Rediscovery of the Elements: Klaproth - Page 2 of 5 - UNT Digital ...
torbernite (copper uranyl phosphate, Cu(UO2)2(PO42 11 H20)," the original specimen from which Klaproth discovered uranium. The labels are original, in ...
[37]
Torbernite from Old Gunnislake Mine, Clitters United Mines ... - Mindat
Torbernite from. Old Gunnislake Mine, Clitters United Mines, Gunnislake, Calstock, Cornwall, England, UK ; Legend (click to dismiss). No locality type selected.<|control11|><|separator|>
[38]
Well Arranged Molecules | Mineral Specimen Torbernite (old classic
Torbernite (old classic- type locale) Johanngeorgenstadt Saxony, Germany 6.7 x 4.3 x 4.8 CM (cabinet) price: $320 pre Tucson 2015 update
[39]
Torbernite mineral information and data
Torbernite ; Formula: Cu(UO2)2(PO4)2·12H2O ; Crystal System: Tetragonal ; Crystal Habit: Tabular, Earthy, Foliated ; Cleavage: Perfect, Distinct, None ; Luster ...
[40]
Torbernite - Encyclopedia - Le Comptoir Géologique
Torbernite is a relatively common secondary mineral in the superficial oxidation zones of uranium deposits; it is present but much rarer in uranium pegmatites.
[41]
Shinkolobwe - PorterGeo Database - Ore Deposit Description
Jan 15, 2016 · There is only minor transport from veins to cavities, usually forming torbernite (Cu[UO2]2[PO4]2•12H2O) and metatorbernite, but also ...
[42]
[PDF] Geology of Uranium Deposits in the Front Range, Colorado
torbernite, metatorbernite, autunite, and kasolite. They occur to average depths of about 100 feet, but may be found as much as 150 feet below the surface ...
[43]
Torbernite Mineral Specimen For Sale - Dakota Matrix Minerals
Out of stockTorbernite ; Availability: Sold ; Size: 1.5 x 4 x 3.5 cm - Miniature ; Formula: Cu(UO2)2(PO4)2·12H2O (RRUFF) ; Locality: Margnac mine, Compreignac, Haute-Vienne, ...
[44]
[PDF] mineral commodity summaries of the czech republic
Jun 15, 2005 · occurred) and Krásno mining districts of the Czech Republic. Besides ... are oxides (uraninite - pitchblende), phosphates (torbernite, autunite), ...
[45]
[PDF] Uranium and uranium mineral systems in South Australia - NET
grade torbernite ore were obtained. Later development was concentrated ... of the Radium Hill area, South Australia. South Australia. Department of ...
[46]
Torbernite | U.S. Geological Survey - USGS.gov
Torbernite is a copper phosphate mineral that contains uranium, making it somewhat radioactive. Although it can be used as a uranium ore, it's more valued ...Missing: Kupfer- Uranit
[47]
Tin, copper, and uranium at Majuba Hill, Nevada
The only uranium minerals detected are the phosphates torbernite and matatorbernite and the arsenate zeunerite. ... The secondary uranium minerals appear to be ...
[48]
[PDF] Extracting uranium from its ores - International Atomic Energy Agency
Both carbonate and acidic leaching solutions have been used. The choice of leaching solution depends on both the chemical and the physical characteristics ...Missing: torbernite | Show results with:torbernite
[49]
Near-infrared spectroscopy of torbernites and metatorbernites
The minerals have a characteristic layer-like structure [5], [6], [7]. Uranium is bound in uranyl phosphate layers. The cations and water are located in the ...Missing: paper | Show results with:paper
[50]
Cu-Fe-U phosphate mineralization of the Hagendorf-Pleystein ...
Mar 9, 2017 · Torbernite was analysed for U, Th and Pb isotopes by laser ablation inductively coupled plasma mass spectrometry techniques. For one domain the ...
[51]
Torbernite - RARE! - Spirifer Minerals
$$65.00Sep 30, 2020 · OUR BEST ALL SPECIMENS RARE FLUORESCENT BY PRICE BY SIZE BY SPECIES BY LOCALITY · $1 - $50 $50 - $200 $200 - $500 $500 - $1000 >$1000.
[52]
Torbernite - D Joyce Minerals
CA$370.00Note: All prices are in Canadian dollars (CAD). International customers are charged in CAD, exchange rate is calculated automatically by your bank/paypal upon ...Missing: value | Show results with:value
[53]
[PDF] Identifying and Managing Radioactive Geological Specimens
This paper summarises how to iden- tify radioactive specimens, establish who is at risk, and set up local rules that keep risk as low as is reasonably ...<|control11|><|separator|>