Thorium phosphate: New mineral phase (Middle Timan, Komi Republic)

AbstractVerbeekite, ideally PdSe2, monoclinic with space-group choicesC2/m,C2 orCm;a= 6.659(7),b= 4.124(5),c= 4.438(6) Å, ß = 92.76(3)°,V= 121.7(4) Å3;a:b:c= 1.6147:1:1.0761, Z = 2, is a new, very rare, primary mineral, intimately associated with secondary oosterboschite {(Pd,Cu)7Se5}, from the Musonoi Cu-Co-Mn-U mine, near Kolwezi, Shaba Province, Democratic Republic of Congo. Additional associated minerals are Cu- and Pd-bearing trogtalite {(Co,Cu,Pd)Se2}, Se-bearing digenite and Se-bearing covellite. The strongest five lines of the X-ray powder-diffraction pattern {din Å (I) (hkl)} are: 4.423(30)(001), 3.496 (30)(110), 2.718(100)(111), 1.955(50)(310 and 1.896(50)(l̄12). The mineral has also been identified, as a single anhedral 25 µm-sized grain, from Hope's Nose, Torquay, Devon, England where it is associated with native gold, chrisstanleyite Ag2Pd3Se4, oosterboschite(?), unnamed Pd2HgSe3and cerussite. At Musonoi, altered verbeekite grains do not exceed 200 µm in size and are anhedral, black, with a black streak and a metallic lustre. The mineral is opaque, brittle, has an uneven fracture, and lacks discernible cleavage. The VHN5ranges 490–610, mean 550 kp/mm2(2 indentations), roughly approximating a Mohs' hardness of 5Ý.Dcalc.= 7.211 g/cm3for the ideal formula. Electron-microprobe analyses (mean of 4 spot analyses) yielded Pd 39.6, Cu 0.5, Se 58.8, total 98.9 wt.%. The empirical formula is (Pd0.99Cu0.02)σ1.01Se1.99, based on Pd+Cu+Se = 3. In plane-polarized reflected light, the mineral is a nondescript grey and is neither pleochroic nor perceptibly bireflectant. Anisotropy is moderate with rotation tints in varying shades of brown. Reflectance spectra and colour values are tabulated. The name honours Dr Théodore Verbeek (1927–1991) who was the first geoscientist to study the Musonoi palladium mineralization in the Democratic Republic of Congo (1955–1967) and who co-discovered this new mineral phase.

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STUDIES OF THE ORGANIC ORIGIN CHEMICAL COMPOUNDS OF BROWN COALS AND CARBONIZED PLANT RESIDUES FROM NORTHERN TIMAN

chemistry of plant raw material ◽

10.14258/jcprm.2020027229 ◽

2020 ◽

pp. 55-64

Author(s):

Lyudmila Sergeyevna Kocheva ◽

Anatoliy Petrovich Karmanov ◽

Vladimir Pavlovich Lutoev ◽

Sergey Aleksandrovich Pokryshkin

Keyword(s):

Komi Republic ◽

Plant Residues ◽

Quantitative Chemical Analysis ◽

A Value ◽

Maximum Value ◽

Brown Coals ◽

Middle Timan ◽

Chemical Studies ◽

Physical And Chemical ◽

Paramagnetic Properties

The results of the physical and chemical studies of the organic matter of Devonian brown coals and rocks with carbonized plant residues from Northern Timan (Russian Arctic) are presented. We used a complex of physical and chemical methods, including IR spectroscopy, EPR spectroscopy, quantitative chemical analysis, pyrolytic gas chromato-mass spectrometry. For comparative studies we used Devonian (Middle Timan) and Jurassic (Griva, Komi Republic, Russia) carbonized plant residues and lignins, isolated from modern wood and non-wood plants. Organic structures of aromatic nature, which are products of the metamorphic transformation of lignins of coal-forming plants, were found in the investigated samples. It was shown that lignin’s relics show pronounced paramagnetic properties, mainly due to the presence of phenoxyl radicals. The concentration of paramagnetic centers reaches a value that is close to the maximum value nорг for carbonaceous substances. Based on quantitative analysis of phenolic products of pyrolysis the composition of lignin relics was calculated, taking into account the ratio of the main structural H, G and S units. Experimental data allowed to put forward the hypothesis that in the composition of Devonian coal-forming plants, as one of the first representatives of forest communities on the planet, included compositionally homogeneous protolignins of H-type, built mainly from p-coumaric structural units.

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Automated mineral analysis in TASK8

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100134661 ◽

1990 ◽

Vol 48 (2) ◽

pp. 212-213

Author(s):

William F. Chambers ◽

Arthur A. Chodos ◽

Roland C. Hagan

Keyword(s):

National Laboratory ◽

Control Program ◽

Mineral Analysis ◽

Alamos National Laboratory ◽

Mineral Phase ◽

Los Alamos National Laboratory ◽

California Institute Of Technology ◽

Mineral Phases ◽

Letter Code ◽

Institute Of Technology

TASK8 was designed as an electron microprobe control program with maximum flexibility and versatility, lending itself to a wide variety of applications. While using TASKS in the microprobe laboratory of the Los Alamos National Laboratory, we decided to incorporate the capability of using subroutines which perform specific end-member calculations for nearly any type of mineral phase that might be analyzed in the laboratory. This procedure minimizes the need for post-processing of the data to perform such calculations as element ratios or end-member or formula proportions. It also allows real time assessment of each data point.The use of unique “mineral codes” to specify the list of elements to be measured and the type of calculation to perform on the results was first used in the microprobe laboratory at the California Institute of Technology to optimize the analysis of mineral phases. This approach was used to create a series of subroutines in TASK8 which are called by a three letter code.

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TEM/AEM characterization of fine-grained clay minerals in very-low-grade rocks: Evaluation of contamination by empa involving celadonite family minerals

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100165938 ◽

1996 ◽

Vol 54 ◽

pp. 694-695

Author(s):

Gejing Li ◽

D. R. Peacor ◽

D. S. Coombs ◽

Y. Kawachi

Keyword(s):

Electron Microscopy ◽

Volcanic Rocks ◽

Analytical Electron Microscopy ◽

Metamorphic Rocks ◽

New Mineral ◽

Chemical Compositions ◽

Low Grade ◽

Fine Grained ◽

Depth Analysis ◽

Mineral Aggregates

Recent advances in transmission electron microscopy (TEM) and analytical electron microscopy (AEM) have led to many new insights into the structural and chemical characteristics of very finegrained, optically homogeneous mineral aggregates in sedimentary and very low-grade metamorphic rocks. Chemical compositions obtained by electron microprobe analysis (EMPA) on such materials have been shown by TEM/AEM to result from beam overlap on contaminant phases on a scale below resolution of EMPA, which in turn can lead to errors in interpretation and determination of formation conditions. Here we present an in-depth analysis of the relation between AEM and EMPA data, which leads also to the definition of new mineral phases, and demonstrate the resolution power of AEM relative to EMPA in investigations of very fine-grained mineral aggregates in sedimentary and very low-grade metamorphic rocks.Celadonite, having end-member composition KMgFe3+Si4O10(OH)2, and with minor substitution of Fe2+ for Mg and Al for Fe3+ on octahedral sites, is a fine-grained mica widespread in volcanic rocks and volcaniclastic sediments which have undergone low-temperature alteration in the oceanic crust and in burial metamorphic sequences.

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A UNIQUE FINDING OF ZIRCON INTO BADDELEYITE TRANSFORMATION (THE ICHETJU ORE OCCURRENCE, THE MIDDLE TIMAN)

Proceedings of higher educational establishments Geology and Exploration ◽

10.32454/0016-7762-2018-1-27-35 ◽

2018 ◽

pp. 27-35

Author(s):

S. G. Skublov ◽

A. O. Krasotkina ◽

A. B. Makeyev ◽

O. L. Galankina ◽

A. E. Melnik

Keyword(s):

High Temperature ◽

Experimental Studies ◽

Middle Timan ◽

Natural Analogues ◽

Opposite Situation ◽

Formation Conditions

Findings of the growth relationships between baddeleyite and zircon are rare, due to significant differences in the formation conditions of the minerals. A reaction replacement (partial to complete) of baddeleyite by zircon is possible during metamorphism accompanied by the interaction with high-Si fluids. The opposite situation, when zircon is replaced by baddeleyite, is extremely rare in the nature. Transformation of zircon from polymineral (compound) ore occurrence Ichetju (the Middle Timan) with the formation of microaggregates of baddeleyite, ratile and florencite has been found out. The size of the largest segregations of baddeleyite does not exceed 10 microns in diameter. Microaggregates are unevenly related to the rim of zircon with a thickness of 10 to 50 rfn, voids and cracks across the grain. Altered zircon rim (a mixture of newly formed minerals) is characterized by sharply increased composition of REE (especially LREE), Y, Nb, Ca, Ti. The composition of Th and U also increases. An overview of the experimental studies on the reaction between zircon and baddeleyite and single natural analogues allows to make a conclusion that the most likely mechanism of the transformation of zircon from ore occurrence Ichetju to baddeleyite (intergrowth with ratile and florencite) is due to the effect of interaction of primary zircon with high-temperature (higher than 500—600°C) alkaline fluids transporting HFSE (REE, Y, Nb, Ti). This is indirectly confirmed by the findings of zircon with anomalous high composition of Y and REE up to 100000 and 70000 ppm respectively.

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