Sum Of REE Research Articles

Rare earth mineralization in ores of the Gurvunur apatite-magnetite deposit (Ozerny ore cluster, Western Transbaikalia)

The Gurvunur apatite-magnetite deposit is located within the Ozerny ore cluster in Wes-tern Transbaikalia. A peculiarity of this object is the presence of rare-earth mineralization in the ores. The main REE concentrator minerals include monazite, allanite, apatite, and epidote. One of the main concentrators of REE is apatite, where the content of REE sum reaches 2.6 wt. %. The REE are mainly represented by light lanthanides, with La up to 1.8 wt. % and Ce up to 2.08 wt. % predominating. Monazite- (Ce) is formed in the process of apatite refining, leading to the monazite fine-grained dissemination and veinlets occurring. Epidote is found in nests and vein-like formations of skarn aggregates. The mineral mainly contains light lanthanides (La up to 5.11 wt. %, Ce up to 2.47 wt. %) and forms gradual transitions to allanite that, in its turn, is also found in the form of isolated segregations or as a part of aggregates of epidote-allanite composition. Light lanthanides with Ce up to 14.35 wt. % and La up to 9.16 wt. % pre-dominate in the allanite composition. The study of the mineral composition and distribution of REE in ores and minerals allows us to conclude that rare-earth mineralization in the ores of the Gurvunur apatite-magnetite deposit was formed as a result of skarning of the carbonate-bearing volcanogenic-sedimentary rocks, and the source of rare-earth mineralization was granodiorites of the Vitimkan intrusive suite.

RARE EARTH ELEMENT RESOURCE POTENTIAL OF SUPER-LARGE DEPOSITS IN EASTERN FENNOSCANDIA

Work has been carried out to assess the rare-earth potential of the main ore minerals -loparite, eudialyte and apatite of the Lovozersky and Khibinsky deposits. Super-large deposits of loparite and eudialyte are associated with the giant Lovozero intrusion (Eastern Fennoscandia, Kola Peninsula). There are a number of apatite deposits in the Khibiny complex. All these ores occupy a leading place in the structure of the raw material of Russia. The highest contents of the sum of rare earth metals are characteristic of loparite ores (the content of ΣREE in loparites is about 28 wt%), and light rare earths sharply prevail over heavy ones, the Ce/Yb ratio is about 78 000. The amount of REE in eudialites is about 2 by mass%. A remarkable feature of eudialyte ores is the high concentrations of the heavy REE group, the Ce/Yb ratio is about 14. The apatites of the Khibiny deposits occupy an intermediate position: the Ce/Yb ratio is 680, and the average concentration of the REE sum is 0.9 wt%. The conditions of formation of apatite, loparite and eudialyte ores are considered.

Rare Earth Element Resource Potential of Super-Large Deposits in Eastern Fennoscandia

This work has been carried out to assess the rare-earth potential of the main ore minerals of the Lovozero and Khibiny deposits. The loparite and eudialyte deposits are associated with the giant Lovozero intrusion (Eastern Fennoscandia, Kola Peninsula). There are several deposits of apatite–nepheline ores in the Khibiny complex. All these ores take the leading position in the structure of the raw material base of Russia. The highest contents of the sum of rare earth metals (REMs) are typical of loparite ores (the content of ΣREE in loparites is about 28 wt %), light rare earths sharply dominate over heavy ones (the Ce/Yb ratio is about 78000). The sum of REEs in eudialytes is about 2 wt %. A remarkable feature of eudialyte ores is the high concentration of the heavy REM group (the Ce/Yb ratio is about 14). The apatites of the Khibiny deposits occupy an intermediate position: the Ce/Yb ratio is 680, and the average concentration of the REE sum is 0.9 wt %. The conditions of formation of apatite, loparite, and eudialyte ores are considered.

Investigation of anthropogenic gadolinium in tap water of polish cities: Gdańsk, Kraków, Warszawa, and Wrocław

In urban areas where tap water is often produced by a purification of water supplied from a river bank filtration, a significant fraction of gadolinium (Gd) total pool is of an anthropogenic origin. It happens because Gd-based contrast agents used in Magnetic Resonance Imaging (MRI) are not removed during wastewater treatment and they are discharged to the environment and returned to the water cycle. Despite the growing number of MRI examinations worldwide, little is known about the anthropogenic Gd in Polish surface water as well as drinking water. The aim of this pilot study was to gain information about the occurrence of emergent pollution as Gd in potable water available for inhabitants of Polish municipal areas. Tap water samples from Gdańsk, Kraków, Wrocław and Warszawa were analyzed by an inductively coupled plasma quadrupole mass spectrometry after their preconcentration by a seaFAST-pico chromatographic system. In this study, the sum of REE was in the range registered in the drinking waters of European urban regions (usually below 100 ng/L). The highest values of the sum of REE total concentrations were observed in the tap water samples collected in Warszawa (37.7 ng/L) and Wrocław (35.9 ng/L and 32.9 ng/L), where water supplies originate from the Wisła River and Oława River, respectively. The highest total Gd concentration was observed in the tap water of Warszawa city where the anthropogenic Gd fraction represented about 90% of the total Gd. The lowest values of the sum REE were registered in tap waters of Gdańsk (sum of REE below 2.2 ng/L) with up to 17% of the anthropogenic Gd. Thus, our study showed the occurrence of the anthropogenic Gd in all analyzed tap waters.

Main and rare earth elements of amphibolites of the Ray-Iz massif (Polar Urals)

Relevance. The Ray-Iz massif contains the Tsentralnoye chromium ore deposit and is unique in terms of variety of metamorphic rock associations. It has been studied since 1932. However, some aspects of geology and petrology in the literature are not fully covered. One of these areas is a vein series of rocks localized in ultramafic rocks. The spatial confinement of amphibolites to the Central zone of metamorphism, which is consistent with the zone of distribution of deposits and ore occurrences of chromites, determines the need for a detailed study. Purpose of work. Study of mineralogical and petrographic characteristics, as well as the geochemistry of lanthanides of amphibolites of the Ray-Iz massif (Polar Urals). Results. The study of the nature of REE distribution in rock-forming minerals made it possible to determine that the variation in the amount of REE (33–75 g/t) within one rock is associated with the quantitative content of the main minerals-concentrators. The main mineral concentrator lanthanides in garnet amphibolites is garnet, while amphibole is in garnet-free pyroxene-bearing amphibolites. Based on the results of the chemical composition of amphibole and coexisting plagioclases and amphibolite garnets, the temperature was calculated using amphiboleplagioclase by T. Holland, J. Blundy, as well as the garnet amphibolite by L. L. Perchuk geothermometers and pressure based on amphibole geobarometer by M. W. Schmidt. Conclusion. The nature of the distribution of lanthanides in the main rock-forming minerals, amphibole and garnet, has been revealed. Comparison of parameters and compositional features of amphiboles made it possible to conclude that there is a direct relationship between temperature, pressure, the sum of REE and TiO2 , as well as (La/Yb)n , in the mineral.

Primorskoye epithermal Ag-Au deposit (Northeast of Russia): geologic aspects, mineralogic and geochemical features, and ore formation conditions

As a potentially large Ag-Au epithermal deposit, Primorskoye comprises the following three areas: Kholodny, Spiridonych, and Teply. This deposit is located in the Omsukchan district of the Magadan Region, where similar deposits, including Dukat, Lunnoye, Goltsovoye, Arylakh, Tidit, and Perevalnoye, have developed. The deposit can be attributed to the Kalalagian volcano-tectonic depression and is localized in a flat-lying rock mass in the Late Cretaceous ignimbrites and rhyolites having thicknesses of greater than 700 m, which is cut through by numerous dykes of medium and major composition. According to the drilling data, the solid mass of leucocratic granites is located in deposits at a depth of 400–500 m with outcrops in the northeastern part of the ore field. The presence of Bi-containing galena and matildite, the availability of mid and high temperature facies of metasomatites (epidote and actinolite), and the specific physical and chemical conditions during the formation of the epithermal Ag-Au ores indicate the intrusive position above and the role of granitoids as generators of high temperature magmatic fluids, which introduced Bi and heated the rocks enclosing the mineralization. The geochemical features of the ores are well correlated with their mineral compositions. The high concentrations of Mn and Ag, elevated concentration of Au, low concentrations of Cu, Pb, Zn, Sb, As, Bi, and Te, low sum of REE, and negative Eu- and positive Се-anomalies were observed. The high values of the Te/Se, Sr/Ba, Y/Ho, and U/Th indicators in the ores are associated with the deposit location in the zone of granitoid massif effect. Further, the physical and chemical parameters of ore formation in the Teply area are unusual and are characterized by high temperatures, low concentrations of salts, and fluid density, which are indicative of the typical “dry steam” conditions. The obtained results allow the Primorskoye epithermal deposit to be attributed to the intermediate class. The information present in the article is practically valuable for the regional forecast and metallogenic developments as well as for searching and assessing the epithermal Ag-Au deposits.

Precipitation of Rare Earth Phosphates from Molten Salts: Particle Size Distribution Analysis

Phosphate precipitation is one of the possible methods for removing rare earth fission product (FP) elements from the technological melts in pyrochemical processes of spent nuclear fuel (SNF) reprocessing. Chemical and phase composition of the phosphates depends on the cationic composition of the melt and, in some instances, on the precipitant employed. Technologically attractive melts include 3LiCl–2KCl and NaCl–2CsCl eutectic mixtures and NaCl–KCl equimolar mixture. Previous studies showed that the normal rare earth orthophosphates (REEPO4) are formed in the 3LiCl–2KCl based melts. In NaCl–KCl and NaCl–2CsCl melts the composition of the precipitate is influenced by the initial phosphate-to-rare earth element molar ratio, and normal as well as double alkali metal – rare earth phosphates (M3REE(PO4)2 or M3REE2(PO4)3) can be produced. After precipitating rare earth FPs, the precipitate needs to be separated from the melt to allow the electrolyte reuse. Solid phosphates can be removed by filtering or collected employing submergible centrifuges. Particle-size distribution (PSD) of the solid precipitate can greatly affect the efficiency of the collection device. After the phosphates are separated they can be further treated for the final disposal, for example, by incorporating them into a suitable glass matrix (a vitrification process). Here again the PSD of the solid material can be important in understanding the properties of the final waste form. Despite the phosphate precipitation process has been studied by various techniques, there is very little information concerning the particle size of the precipitates formed in the process. In the present work the effect of the initial phosphate precipitant-to-rare earth mole ratio on the particle size of the rare earth phosphates was investigated. The experiments were performed in NaCl–2CsCl and NaCl–KCl based melts at 650 and 750 oC, respectively. The REEs studied included La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb, where the heavier lanthanides (which are not the fission products) were included for comparison. Phosphate precipitant was added in the amount required for 50 and 100 % precipitation of the REE. In addition, the melts containing the mixture of REEs imitating their content in a typical light water reactor SNF arriving for reprocessing were studied. Particle size of the precipitated phosphates was determined by laser diffraction method employing ANALYSETTE 22 NanoTec (Fritsch) instrument with a measuring range of 0.02–2100 μm. The measurements were performed both with and without using ultrasound to asses the effect of ultrasonic treatment on the particle deagglomeration. The obtained results showed that the particle size of the precipitated phosphates typically lies in the range of 0.1–100 μm. Fraction of the particles with the size below 1 μm is relatively small. The results of the measurements showed that the particles of the phosphates are agglomerated, maxima in the PSD curves shift towards lower values after the ultrasonic treatment of the samples. Heavier lanthanides tend to form larger particles. For example, maxima in the PSD curves of the phosphates produced at 100 % precipitation in NaCl–2CsCl melts shifted from ca. 6 μm for lanthanum to ca. 20 μm for ytterbium. The effect of the initial phosphate-to-REE molar ratio in the melt on the particle size is not straightforward. For the lighter lanthanides (from Ce to Sm) PSD curves for the precipitates obtained at 50 % degree of precipitation have two maxima – around 1 and 10–20 μm, and the average particle size is smaller than for the solids obtained at 100 % REE precipitation. For the heavier lanthanides the average size of the particles obtained at 50 % REE precipitation was greater than at complete precipitation. Cationic composition of the melt does not significantly affect the average size of the particles of REE phosphates, although influences the particle-size distribution. Examples of the results obtained for precipitation of the sum of REE from NaCl–2CsCl and NaCl–KCl based melts are shown in the Figure. Bulk of the particles has the size within 1–100 μm limits. Figure 1

PILOTAŻOWE BADANIA PIERWIASTKÓW ZIEM RZADKICH W STREFIE KONTAKTU BLOKU MAŁOPOLSKIEGO Z BLOKIEM GÓRNOŚLĄSKIM

PILOT STUDIES OF RARE EARTHS IN THE CONTACT ZONE OF THE MAŁOPOLSKA BLOCK WITH THE UPPER SILESIA BLOCK Abstract. The paper presents the results of a pilot prospecting study on archived drill cores from boreholes in the contact zone of the Malopolska Block with the Upper Silesia Block, with a use of a Portable XRF spectrometer Delta 50 Premium (Olympus). A few hundred measurements of concentrations of La, Ce and other trace elements were made in selected boreholes from the prospective zones for the occurrence of Mo Cu–W ore mineralization. The maximum content for La (400 ppm) and Ce (600 ppm) measured by the Portable spectrometer has been found in the Ko-4 borehole (depth interval 450–550 m). In the depth interval of ca. 400–1300 in the other boreholes (Pz-36, RK-2 and Cianowice-2), the maximum La and Ce contents were approximately twice lower than in the Ko-4. The study also shows an interdependence of the occurrence of LREE with Sr, Y or Th. The most interesting samples were additionally analyzed by ICP-MS and electron microprobe (CAMECA SX-100). The sum of REE (ICP-MS) in four samples that reveal the highest contents of these elements varied from ca. 0.02 to 0.1%. Total REE contents for samples normalized to the upper continental crust are low (1–10). The highest REE concentrations in samples of hydrothermal breccia were found in the Ko-4 borehole (depth ca. 500 m). They reach for the Ce (305.1 ppm), Nd (266.9 ppm), La (258 ppm) and Sm (31.3 ppm). Other REE occur at low concentrations. This is clearly visible on the standard logarithmic charts of REE concentration in relation to their content in chondrite and in the upper part of the continental crust. Characteristic is the lack of negative Eu anomaly on both charts. In the microprobe study, calcioancylite-(Ce), synchysite-(Ce) as well as bastnasite and zircon were also detected in addition to the unidentified minerals from the anhydrous phosphate group enriched with REE (mainly Ce, La, and Nd) and monazite. The form and composition of the REE mineralization indicate clearly that it is of hydrothermal nature. During hydrothermal processes, REE underwent redeposition and concentrated within breccia and tectonic zones in the metasomatic changed rocks. The data on REE concentrations, presented in this paper, are only of indicative significance. The REE contents are much lower than the most interesting results obtained within the framework of research projects carried out in other geological units in Poland and published in separate papers.

Ion-Exchange Separation and Concentration of Ions of Rare-Earth Elements on Fibrous Sorbents

Acid-base properties and selectivity of absorption such ions as REE (Eu3+, Gd3+, Nd3+, Yb3+) from solutions with various ionic force by the fibrous ampholytes PAN-FOSPAN and PAN-IDUC are investigated. PAN-FOSPAN shows the greatest selectivity to ions of REE. This fact can be used for division and the subsequent definition of ions. PAN-IDUC as a high selective fibrous sorbent after alkaline treatment is perspective one for absorption of the REE sum.

Rare Earth Elements of Orzeskie Beds of South-West Part Upper Silesian Coal Basin (Poland) / Pierwiastki Ziem Rzadkich Z Pokładów Węgla Warstw Orzeskich Południowo-Zachodniej Części Gzw (Polska)

Abstract The subject of the research concerned the coal samples from 360/1, 361 and 362/1 seams of the Orzesze beds in the “Pniówek” coal mine. The obtained samples were characterized by low ash content - 2.22- 6.27% of the mass. The chemical composition of the ash indicates the presence of aluminosilicate minerals in the analyzed coal samples - most likely clay minerals, the presence of which has been confirmed in microscopic tests of the petrographic composition of channel samples of coal. The content of rare earth elements (REE sum) in the ash of the tested coal seams ranged from 364 to 1429 ppm. Variation of the REE content has been observed within a single seam. The fraction of REE indicates a relation with a mineral substance. No relation of the REE fraction and the presence of red beds has been found based on the tested samples. The content of REE found in ash, normalized to chondrites, is characterized by LREE enrichment in relation to HREE. The Eu anomaly is most likely related to tuff and tonstein levels occurring in Orzesze beds, which accompany the coal seams in the Upper Silesian Coal Basin (i.a., south of the studied area). The research has indicated that LREE in the tested samples are more related to the mineral substance, while HREE have a stronger affinity with organic substances.

Geochemical fingerprint of siliceous, amphibolitic and magnetitic itabirite types of the region of Serra Azul – Quadrilátero Ferrífero, MG

Banded iron formations are important providers of information about the evolution of the hydrosphere, atmosphere, biosphere and lithosphere of the Earth. This study gathers data from the geochemical investigation of major, minor and trace elements (including rare earth elements) of the siliceous, amphibolitic and magnetitic types of itabirite from the Cauê Formation, sampled in the Serra Azul region (Quadrilátero Ferrífero).Observing the trace elements described as tracers of detrital contamination can be inferred that the magnetitic itabirite has the highest contamination and that the siliceous type has the lowest one.Although there are differences in the total sum of REE in the three itabirite types of Serra Azul, there are no discrepancies in the REE spectrum of each type. The itabirite types have as common characteristics in their REE spectrum: i) positive Eu anomalies (Planavsky et al., 2010); ii) HREE enrichment in relation to the LREE; iii) ratios of (Sm/Yb)SN<1 and (Eu/Sm)SN>1 (Bau & Möller, 1993). The magnetitic and the siliceous itabirites had positive Y anomalies, a common characteristic that appeared in some amphibolitic samples. On the other hand, the other amphibolitic samples had negative Y anomalies.

Processing of REE-containing Ores and Concentrates

The choice of the method of monazite opening determines the further technology. The article presents the results of the studies of monazite decomposition with sulfuric and nitric acid. Also, the issues concerning the extraction processing of opening nitrate solutions, containing the sum of REE, with their division into the groups and the disposal of radioactive waste of REE producing are considered.

A new method for primary evaluation of the outlook for rare earth element ores

A new method for primary evaluation of REE ore is based on classification of REE by the level of demand from industry. For their primary evaluation, it is proposed to use an outlook coefficient (Koutl) for REE ores, which is a ratio of the relative amount of critical REE to the relative amount of excess REE: Koutl= (Nd + Eu + Tb + Dy + Er + Y)/REE sum: (Ce + Ho + Tm + Yb + Lu)/REE sum. The use of this coefficient for comparison of REE ores pertaining to various genetic types makes it possible not only to grade newly discovered deposits at the early stage of their study but also to evaluate a possible contribution of well-known deposits, including those currently mined, to output of REE.

The Darasun gold deposit, Eastern Transbaikal region: Chemical composition, REE patterns, and stable carbon and oxygen isotopes of carbonates from ore veins

The chemistry, REE patterns, and carbon and oxygen isotopic compositions of carbonates from ore veins of the Darasun deposit are discussed. In addition to the earlier described siderite, calcite, and carbonates of the dolomite-ankerite series, kutnahorite is identified. The total REE content in Fe-Mg carbonates of the dolomite-ankerite series (2.8–73 ppm) is much lower than in later calcite (18–390 ppm). δ13C of Fe-Mg carbonates and calcite varies from +1.1 to −6.7‰ and from −0.9 to −4.9‰, respectively. δ18O of Fe-Mg carbonates and calcite varies from +17.6 to 3.6‰ and from +15.7 to −0.5‰, respectively. The REE sum and carbon and oxygen isotopic compositions reveal zonal distribution relative to the central granodiorite porphyry stock. The correlation between the carbon and oxygen isotopic compositions and REE sum reflects variations in the physicochemical formation conditions and composition of ore-forming fluid. The isotopic composition of fluid is calculated, and possible sources of its components are considered. Earlier established evidence for a magmatic source of ore-forming fluid and participation of meteoric water in ore formation is confirmed. Geochemical evidence for interaction of ore-forming fluid with host rocks is furnished. The relationships between the REE sum, on the one hand, and carbon and oxygen isotopic compositions of hydrothermal ore-forming fluid, on the other, are established.

The Gumeshevo skarn-porphyry copper deposits in the Central Urals, Russia: Evolution of the ore-magmatic system as deduced from isotope geochemistry (Sr, Nd, C, O, H)

The Early Devonian Gumeshevo deposit is one of the largest ore objects pertaining to the dioritic model of the porphyry copper system paragenetically related to the low-K quartz diorite island-arc complex. The (87Sr/86Sr)t and (ɛNd)t of quartz diorite calculated for t = 390 Ma are 0.7038–0.7045 and 5.0–5.1, respectively, testifying to a large contribution of the mantle component to the composition of this rock. The contents of typomorphic trace elements (ppm) are as follows: 30–48 REE sum, 5–10 Rb, 9–15 Y, and 1–2 Nb. The REE pattern is devoid of Eu anomaly. Endoskarn of low-temperature and highly oxidized amphibole-epidote-garnet facies is surrounded by the outer epidosite zone. Widespread retrograde metasomatism is expressed in replacement of exoskarn and marble with silicate (chlorite, talc, tremolite)-magnetite-quartz-carbonate mineral assemblage. The 87Sr/86Sr ratios of epidote in endoskarn and carbonate in retrograde metasomatic rocks (0.7054–0.7058 and 0.7053–0.7065, respectively) are intermediate between the Sr isotope ratios of quartz dioritic rocks and marble (87Sr/86Sr = 0.70784 ± 2). Isotopic parameters of the fluid equilibrated with silicates of skarn and retrograde metasomatic rocks replacing exoskarn at 400°C are δ18O = +7.4 to +8.5‰ and δD = −49 to −61‰ (relative to SMOW). The δ13C and δ18O of carbonates in retrograde metasomatic rocks after marble are −5.3 to +0.6 (relative to PDB) and +13.0 to +20.2% (relative to SMOW), respectively. Sulfidation completes metasomatism, nonuniformly superimposed on all metasomatic rocks and marbles with formation of orebodies, including massive sulfide ore. The δ34S of sulfides is 0 to 2‰ (relative to CDT);87Sr/86Sr of calcite from the late calcite-pyrite assemblage replacing marble is 0.704134 ± 6. The δ13C and 87Sr/86Sr of postore veined carbonates correlate positively (r = 0.98; n = 6). The regression line extends to the marble field. Its opposite end corresponds to magmatic (in terms of Bowman, 1998b) calcite with minimal δ13C, δ18O, and 87Sr/86Sr values (−6.9 ‰, +6.7‰, and 0.70378 ± 4, respectively). The aforementioned isotopic data show that magmatic fluid was supplied during all stages of mineral formation and interacted with marble and other rocks, changing its Sr, C, and O isotopic compositions. This confirms the earlier established redistribution of major elements and REE in the process of metasomatism. A contribution of meteoric and metamorphic water is often established in quartz from postore veins.

PINK LANTHANITE-(Nd) FROM WHITIANGA QUARRY, COROMANDEL PENINSULA, NEW ZEALAND

Lanthanite-(Nd) occurs in tuffaceous, altered andesitic agglomerate in the Whitianga quarry, Coromandel Peninsula, New Zealand. The usual platy habit is represented, together with more unusual blocky equant crystals. The former show the new forms {201}, {102} and {111}, and the latter, {111}. ICP–MS analyses show that the distribution of REE (and Ga) is consistent with the formulation (Nd 0.63 La 0.59 Ce 0.35 Pr 0.15 Sm 0.10 Gd 0.069 Y 0.06 Eu 0.03 Dy 0.02 Ga 0.01 ) ∑ 2.04 (CO 3 ) 3 ·8H 2 O; the REE sum of 2.04 is due solely to rounding errors. The find represents the first occurrence of this rare mineral in New Zealand. The mineral formed under comparatively oxidizing conditions. The REE are probably scavenged by warm waters circulating through underlying greywackes of the Manaia Hill Group. We also characterized the lanthanite-(Nd) by X-ray diffraction (powder method) and Raman spectroscopy.

Cordylite-(Ce); a crystal chemical investigation of material from four localities, including type material

Six cordylites from the four known localities [Narssarssuk (Greenland), Mont St. Hilaire (Canada), Bayan Obo (China), and Kola Peninsula (Russia)] were investigated by electron microprobe and X-ray single-crystal structure determination, and a seventh sample was investegated by X-ray methods only. The material studied included type cordylite. The idealized formula for cordylite is redefined as (Na 12xCax/2)BaCe2(CO3)4F, 0 , x , 1, with Ce for the sum of REE; the SrO content may reach about 5.7%. All of our structure refinements (63/mmc; a o 5.10, c o 23.10 A ˚) agree very well among themselves and with the published structures of ‘‘baiyuneboite-(Ce)’’ and unnamed (Ca 0.5M0.5)BaCe2(CO3)4F. Cordylite has a sheet structure formed of (001) layers of [Ba] [CO3] [Ce,CO3] [Na,F] [Ce,CO3] [CO3] [Ba] stacked along [001]. The interatomic distances are as expected, with the exception of unshielded Na-F dis

X-Ray and Optical Data for a Rare Earth–Poor Eudialyte from the North–Central Alaska Range

AbstractPowder X-ray and optical data have been recorded for a sample of exceptionally rare earth-poor eudialyte (Na12(Ca, REE)6(Fe2+,Mn,Mg)3Zr3(Zr,Nb)x[Si9O27−y(OH)y]2[Si3O9]2(C1,F)z, with x = 0. 1–0.9, y = 1–3 and z = 0.7–1.4) from a pegmatitic vein associated with the peralkaline Windy Fork granite in the north–central Alaska range. The eudialyte is uniaxial positive with ω= 1.6062(2), ε= 1.6138 (3) and microprobe analyses indicate that the sum of REE + Yis less than 0.1 weight percent. Refined unit cell dimensions are: a = 14.2572(4), c = 30.1338(27), Dx= 2.67, F30= 128 (0.006, 42), M20= 76. An indexed powder diffraction pattern is given.