Geology of Ore Deposits

LOCATION (MRDS, 2011)

T.17S 53E Sec 20 36.46248 -116.0491 West mine
T.17S 53E Sec 21 36.46058 -116.0227 East prospect

The Congress Mine is part of the Johnnie District of Joseph Tingley (1998).

The Johnnie mining district is located on the north-west flank of the Spring Mountains, 3 miles northeast of Johnnie in T. 17 S., R. 53 E. It is the second largest gold-producing district in southern Nye County (Cornwall, 1972:38).

The Johnnie district extends from the north flank of Mount Sterling, on the northwest end of the Spring Mountains, southwest to the southwestern tip of Mount Montgomery. It includes Mt. Schader, the town of Johnnie, and a small area on the northeast side of Mount Sterling sometimes considered to be the separate Mount Sterling district. Wheeler (1872) included the Johnnie area in his large Timber Mountain district which also included the Charleston district (Tingley, 1998).
PREVIOUS NAMES

Johnnie Snapper, Montgomery, Mount Sterling, Timber Mountain (MRDS, 2011, Tingley, 1998).

PREVIOUS WORK

Wheeler, 1872, p. 52; Hill, 1912, p. 222; Lincoln, 1923, p. 172; Stoddard, 1932, p.68; Lotz, 1934, p. 22; Kral, 1951, p. 86; Averett, 1962, p. 71; Cornwall, 1972, p. 38 (Tingley, 1998).

MINE GEOLOGY

[In the Johnnie District] The gold occurs in prominent and persistent quartz veins along faults in sandstone , shale, and limestone of the Wood Canyon and Carrara Formations. The largest ore shoots are in the Johnnie mine, where the vein follows a fault between the two formations (Corwall, 1972:38).

Mapping by Workman and others (2002, Figure 17 this report) shows the Johnnie, Overfield north and Overfield south mines as lying along a fault that marks a bedding plane between the Cambrian Bonanza King Formation (Ꞓb) and Proterozoic and Lower Cambrian Woods Canyon Formation (ꞒZw).

At the Congress Mine, mineralization is along the Congress Fault. Veins occur at the contact of the Congress Fault with Zabrinski Quartzite where it is a brecciated bedding plain fault with the Bonanza King, Wood Canyon and Cararra formations.

Chevkinite has been found in three localities of syenite pegmatite in the Oslo region, one of which also carries perrierite. The perrierite and chevkinite do not coexist. The perrierite contains a loparite (with pyrophanite) core. The unheated chevkinites and perrierite gave no X-ray diffraction patterns, due to their metamict state. All chevkinites show well-developed chevkinite X-ray patterns when heated in air, but in the sample with Ce) La the chevkinite pattern is weak and a strong CeO2 pattern is also present. Unit-cell dimensions correspond with cell paramoters given in the literature. The chemical compositions of the chevkinites and perrierite investigated were found to be relatively uniform and suited the lormula,{ ,BCrSirO*2 wherezl:

The ground water resources of the Kozuf region are directly related with litological, hydrogeological and tectonic phenomena and processes which take place from paleozoik until recent geological past, which ends volcanic activity of Mount Kozuf. Based on the results of previous regional and detailed hydrogeological studies the investigated area by structural type of porosity that occurs in rocks that are present can be divided in: boundary type of aquifers, fracture type of aquifers, karst-fractured type of aquifers and conditional waterless terrain. The ground water resources of the region is mostly associated with upper cretaceous limestone, characterized by fractured-cavernosal porosity. The upper cretaceous limestones of this region are affected by different level of кarstification to the isolationist base represented by old Paleozoic shale (phylite, argiloshist and sandstone). Somewhere process of karstification to waterproof surface is completely finished (eg sources in the Valley Zharnica), and sometimes still is not finished.

Sr, V * Zn) in the wines produced at home in the Tikveš area with the application of the methods of ICP-AES and (ETAAS) are shown. The paper also presents the correlations made on the basis the presence of certain trace elements in the soil on which the specified variety of grape wine is grown and the same elements in the wine which is produced from that type of grape. The correlations basically point to the fact that there is no great correlation between the presence of the determined trace elements in the soil and wine produced at home. Namely, these correlations for the determined geochemical pairs are the following: Al soil /Al vine (0.04); As soil /As vine (0.11); Ba soil /Ba vine (0.23); Ca soil /Ca vine (0.02); Cd soil /Cd vine (-0.06); Co soil /Co vine (-0.26); Cr soil /Cr vine (-0.04); Cu soil /Cu vine (0.04); Mg soil /Mg vine (-0.30); Mn soil /Mn vine (-0.40); Na soil /Na vine (0.11); Ni soil /Ni vine (0.03); Pb soil /Pb vine (0.27); The lack of significant correlations between the given geochemical pairs is a result of a few moments such as: (1) the presence of trace elements in the soil is determined up to the depthof 30 'B. (2) trace elements in soils are present mainly in the silicate matrix from which the elements are not easily excreted into aqueous solutions. (3) the root system of the grape vine is at a much greater depth of 30 'm.

A rarely occurring complete tetrahedrite-tennantite solid solution has been reported from the Schendleck area (Lower Austria). The fahlores from this region (“Schendleck-type ” fahlore) represents an unique type, exhibiting a strong inhomogeneity and a wide range of the Sb/(Sb+As) ratio (from 5 to 95 % tetrahedrite-content). The presence of the Schendleck-type fahlore indicates that the complete fahlore solid solution between the nearly pure Sb-endmember and the nearly pure As-endmember exists in nature. Zusammenfassung Das seltene Vorkommen einer kompletten Fahlerz-Mischkristallreihe (Tetraedrit-Tennantit) wird aus dem Bereich Schendleck (Niederösterreich) dokumentiert. Die einzigartigen Fahlerze dieses Gebietes („Schendleck-Typ “ Fahlerze) zeigen starke Inhomogenitäten und einen weiten Bereich des Sb/(Sb+As) Verhältnisses (von 5 bis 95 % Tetraedrit-Gehalt). Das Auftreten dieses Schendleck-Typ Fahlerzes weist darauf hin, dass die komplette Fahlerz-Mischkristallreihe zwischen dem na...

The Wa-Lawra greenstone belt is located in northwest Ghana and is largely dominated by Birimian metavolcanics, volcaniclastics, and metasediments with some intrusive suites. These rocks are capped by mineralized laterites in most localities, especially in the Kunche area. Previously, regolith materials such as laterites and soils from mixed sources were used to identify pathfinder elements of gold in the belt. However, in-situ (residual) laterites will better represent their underlying formations than transported laterites because transported laterites may contain extraneous sources of element enrichment caused by pollution, which is unrelated to gold mineralization. Therefore, in this study, petrographic studies of residual laterites and statistical analyses of trace element geochemical data of the residual laterites were performed to identify the pathfinder elements of gold in the Wa-Lawra greenstone belt. Six fresh residual laterite samples were used for the petrographic studies,...

The distribution of Re in ores of the Mikheevskoe Mo-Cu deposit in the South Urals is studied. It is established that the grade of Re in the ores usually does not exceed 0.5 g/t. A positive correlation between concentrations of Re and Mo (correlation coefficient 0.94), and Re and Cu (correlation coefficient 0.52) is found. EMPA of individual flakes of molybdenite showed that a Re content higher than the detection limit has been measured in most flakes studied, as a rule as high as 0.4-0.5 wt %, but occasionally reaching 1.34 wt %. Re within flakes of molybdenite is irregularly distributed. Patchy, linear, and concentric zoned patterns of zones with elevated Re content (usually 0.5-1 wt % Re, sometimes higher) are found against the lower con tent (up to 0.2 wt % Re) that is regularly distributed within the flake. Later hydrothermal processes and mechanical deformation of flakes result in epigenetic Re redistribution in molybdenite that leads to homogenization of molyb denite composition and smoothing of primary pattern, or removal of Re from molybdenite.

The Bereznyakovskoe ore field is situated in the Birgil'da-Tomino ore district of the East Ural volcanic zone. The ore field comprises several centers of hydrothermal mineralization, including the Central Bereznyakovskoe and Southeastern Bereznyakovskoe deposits, which are characterized in this paper. The disseminated and stringer-disseminated orebodies at these deposits are hosted in Upper Devonian-Lower Carboniferous dacitic-andesitic tuff and are accompanied by quartz-sericite hydrothermal alteration. Three ore stages are recognized: early ore (pyrite); main ore (telluride-base-metal, with enargite, fahlore-telluride, and gold telluride substages); and late ore (galena-sphalerite). The early and the main ore stages covered temperature intervals of 320-380 to 180 ° C and 280-300 to 170 ° C, respectively; the ore precipitated from fluids with a predominance of NaCl. The mineral zoning of the ore field is expressed in the following change of prevalent mineral assemblages from the Central Bereznyakovskoe deposit toward the Southeastern Bereznyakovskoe deposit: enargite, tennantite, native tellurium, tellurides, and selenides → tennantite-tetrahedrite, tellurides, and sulfoselenides (galenoclausthalite) → tetrahedrite, tellurides, native gold, galena, and sphalerite. The established trend of mineral assemblages was controlled by a decrease in , and and an increase in pH of mineral-forming fluids from early to late assemblages and from the Central Bereznyakovskoe deposit toward the Southeastern Bereznyakovskoe deposit. Thus, the Central Bereznyakovskoe deposit was located in the center of an epithermal high-sulfidation ore-forming system. As follows from widespread enargite and digenite, a high Au/Ag ratio, and Au-Cu specialization of this deposit, it is rather deeply eroded. The ore mineralization at the Southeastern Bereznyakovskoe deposit fits the intermediate-or low-sulfidation type and is distinguished by development of tennantite, a low Au/Ag ratio, and enrichment in base metals against a lowered copper content. In general, the Bereznyakovskoe ore field is a hydrothermal system with a wide spectrum of epithermal mineralization styles.

Light-blue barite from Jebel Ouichane in Morocco forms blade-like tabular crystals (up to ca. 10 cm) with superb transparency and lustre and represents one of the most spectacular gem-quality worldwide. The barite is hosted by iron-ore-bearing skarns, developed within Jurassic-Cretaceous limestones, and occurs in close spatial association with calcite. The crystals have their cores enriched in Sr and contain abundant monophase (liquid) fluid inclusions of primary and pseudosecondary origin. The barite probably precipitated slowly at a relatively low supersaturation and under the control of a surface reaction precipitation mechanism. However, there were some episodes during its formation with a fast growth rate and the coupled dissolution and recrystallization processes. A combination of fluid inclusion data and stable δ18O value for barite (+ 6.71‰ VSMOW) suggests that low-salinity barite-forming solutions resulted from the mixing of strongly-diluted meteoric waters (enriched in lig...

Homogenization temperatures and salinity data are presented for fluid inclusions from hydrothermal gangue minerals (quartz and fluorite) associated with porphyry wolframite-molybdenite-arsenopyrite-sphaleritebismuth-chalcopyrite-cassiterite mineralization within the Fire Tower ore zone, Mt Pleasant, New Brunswick. The data indicate that ore mineral precipitation occurred within a temperature range of 260 ° to 490 °C from moderate to high salinity (10-42wt% NaC1 equivalent) aqueous fluids. Two stages of hydrothermal activity characterized by high (>30 wt% NaC1 equivalent) salinity fluids are recognized; one which occurred at relatively high temperature (350°-490 °C); and one which took place at lower temperature (180°-250°C). The high salinity, high temperature stage is interpreted to be the result of resurgent boiling. Dilution of these early fluids by convecting meteoric water resulted in low to moderate salinity fluids, which dominate the inclusion population. The low temperature, high salinity fluid inclusions are interpreted to represent late residual fluids derived from boiling which occurred as a result of a change in the pressure regime from dominantly lithostatic to hydrostatic conditions.

The distribution of Re in ores of the Mikheevskoe Mo-Cu deposit in the South Urals is studied. It is established that the grade of Re in the ores usually does not exceed 0.5 g/t. A positive correlation between concentrations of Re and Mo (correlation coefficient 0.94), and Re and Cu (correlation coefficient 0.52) is found. EMPA of individual flakes of molybdenite showed that a Re content higher than the detection limit has been measured in most flakes studied, as a rule as high as 0.4-0.5 wt %, but occasionally reaching 1.34 wt %. Re within flakes of molybdenite is irregularly distributed. Patchy, linear, and concentric zoned patterns of zones with elevated Re content (usually 0.5-1 wt % Re, sometimes higher) are found against the lower con tent (up to 0.2 wt % Re) that is regularly distributed within the flake. Later hydrothermal processes and mechanical deformation of flakes result in epigenetic Re redistribution in molybdenite that leads to homogenization of molyb denite composition and smoothing of primary pattern, or removal of Re from molybdenite.

In the Republic of Congo, Banded iron formations (BIFs) occur in two areas: the Chaillu Massif and the Ivindo Basement Complex, which are segments of the Archean Congo craton outcropping in the northwestern and southwestern parts of the country. They show interesting potential with significant mineral resources reaching 2 Bt and grades up to 60% Fe. BIFs consist mostly of oxide-rich facies (hematite/magnetite), but carbonate-rich facies are also highlighted. They are found across the country within the similar geological sequences composed of amphibolites, gneisses and greenschists. The Post-Archean Australian Shale (PAAS)-normalized patterns of BIFs show enrichment in elements such as SiO

The Koru deposit is a typical intermediate sulfidation base-metal ( Au) example of volcanicvolcaniclastic hosted mineralization in the Biga Peninsula and northwestern Turkey. Ore deposition was controlled by collisional and post-collisional tectonics related to the closure of the Tethys Ocean. Galena, baryte and quartz are main minerals, accompanied by minor amounts of sphalerite, pyrite, chalcopyrite, covellite and marcasite. The homogenization temperature of fluid inclusions indicates two distinct fluid pulses, one at a temperature commensurate with epithermal mineralization and boiling/near boiling conditions at c. 350 ºC, the second approximately 150-200 ºC lower. Salinity in both instances was from 11.0 to 0.2 wt. % NaCl. The δD and δ 18 O values of water in equilibrium with early quartz and fluid inclusions, plot close to the magmatic water box indicating the source of the high temperature fluid was magmatic. δD and δ 18 O values from early and late baryte trend towards the meteoric water line (MWL), but this is not due to mixing with meteoric water and indicates equilibration with alteration assemblages. LA-ICP-MS analyses of fluid inclusions reveal high Cu-Zn-Pb concentrations in the fluids, despite their low salinity, transported as chloride complexes. The range of temperatures within the early quartz and sphalerite samples can be 2 explained by pressure variations during vein and fracture opening from near lithostatic to hydrostatic pressure.

The distribution of Re in ores of the Mikheevskoe Mo-Cu deposit in the South Urals is studied. It is established that the grade of Re in the ores usually does not exceed 0.5 g/t. A positive correlation between concentrations of Re and Mo (correlation coefficient 0.94), and Re and Cu (correlation coefficient 0.52) is found. EMPA of individual flakes of molybdenite showed that a Re content higher than the detection limit has been measured in most flakes studied, as a rule as high as 0.4-0.5 wt %, but occasionally reaching 1.34 wt %. Re within flakes of molybdenite is irregularly distributed. Patchy, linear, and concentric zoned patterns of zones with elevated Re content (usually 0.5-1 wt % Re, sometimes higher) are found against the lower con tent (up to 0.2 wt % Re) that is regularly distributed within the flake. Later hydrothermal processes and mechanical deformation of flakes result in epigenetic Re redistribution in molybdenite that leads to homogenization of molyb denite composition and smoothing of primary pattern, or removal of Re from molybdenite.

The authors’ aim was determination of estimated gold resources on the basis of the geological data analysis. The following methods were used for calculation of resources: parameters of ore bodies at gold occurrences, data of geochemical anomalies, geological evidence indicating existence of ore bodies in the depth. The territory of Georgia includes part of the Alpine-Himalayan mountain-fold belt, which is a result of interaction of the Scythian and South Caucasus microplates geologically developed in the marginal area of the Eurasian continent. Four gold bearing complexes are found on the territory of Georgia: 1) Activated in Middle Jurassic south Caucasus microcontinent slope and slope root zones, which are built by Palaeozoic Middle-Early Jurassic marginal sea flischoid-terrigenous sediments (potential in Middle Jurassic deposits in granite stocks Lukhra and in carbonaceous suite Arshira, Lasilli, on Svaneti ridge; 2) The Greater Caucasus southern slope suture zone (“main thrusts”...

Automated Scanning Electron Microscopy (ASEM) systems are applied in the mining industry to quantify the mineralogy of the ore feed and products. With society pushing towards sustainable mining, this quantification should be comprehensive and include trace minerals since they are often either deleterious or potential by-products. Systems like QEMSCAN ® offer a mode for trace mineral analysis (TMS mode); However, it is unsuitable when all phases require analysis. Here, we investigate the potential of detecting micron-sized trace minerals in fieldscan mode using the QEMSCAN ® system with analytical settings in line with the mining industry. For quality comparison, analysis was performed at a mining company and a research institution. This novel approach was done in full collaboration with both parties. Results show that the resolution of trace minerals at or below the scan resolution is difficult and not always reliable due to mixed X-ray signals. However, by modification of the species identification protocol (SIP), quantification is achievable, although verification by SEM-EDS is recommended. As an add-on to routine quantitative analysis focused on major ore minerals, this method can produce quantitative data and information on mineral association for trace minerals of precious and critical metals which may be potential by-products in a mining operation.

Introduction and aims 1 A classification scheme for ore deposits 2 What makes a viable mineral deposit? 4 Some useful definitions and compilations 6 Natural resources, sustainability, and environmental responsibility 11 Summary and further reading 15 PART 1 IGNEOUS PROCESSES 1 IGNEOUS ORE-FORMING PROCESSES 19 1.1 Introduction 19 1.2 Magmas and metallogeny 20 1.3 Why are some magmas more fertile than others? The "inheritance factor" 28 1.4 Partial melting and crystal fractionation as ore-forming processes 37 1.5 Liquid immiscibility as an ore-forming process 54 1.6 A more detailed consideration of mineralization processes in mafic magmas 57 1.7 A model for mineralization in layered mafic intrusions 71 Summary and further reading 74 2 MAGMATIC-HYDROTHERMAL ORE-FORMING PROCESSES 75 2.1 Introduction 75 2.2 Some physical and chemical properties of water 76 2.3 Formation of a magmatic aqueous phase 79 2.4 The composition and characteristics of magmatichydrothermal solutions 85 2.5 A note on pegmatites and their significance to granite-related ore-forming processes 93 2.6 Fluid-melt trace element partitioning 96 2.7 Water content and depth of emplacement of granitesrelationships to ore-forming processes 101 2.8 Models for the formation of porphyry-type Cu, Mo, and W deposits 106 2.9 Fluid flow in and around granite plutons 108 2.10 Skarn deposits 113 2.11 Near-surface magmatichydrothermal processes-the "epithermal" family of Au-Ag-(Cu) deposits 117 2.12 The role of hydrothermal fluids in mineralized mafic rocks 122 Summary and further reading 125 PART 2 HYDROTHERMAL PROCESSES 3 HYDROTHERMAL ORE-FORMING PROCESSES 129 3.1 Introduction 129 3.2 Other fluids in the Earth's crust and their origins 130 Contents 4 SURFICIAL AND SUPERGENE ORE-FORMING PROCESSES 219 4.1 Introduction 219 4.2 Principles of chemical weathering 220 4.3 Lateritic deposits 223 4.4 Clay deposits 233 4.5 Calcrete-hosted deposits 235 4.6 Supergene enrichment of Cu and other metals in near surface deposits Summary and further reading 5 SEDIMENTARY ORE-FORMING PROCESSES 5.1 Introduction 5.2 Clastic sedimentation and heavy mineral concentration-placer deposits 5.3 Chemical sedimentation-banded iron-formations, phosphorites, and evaporites 5.4 Fossil fuels-oil/gas formation and coalification Summary and further reading PART 4 GLOBAL TECTONICS AND METALLOGENY 6 ORE DEPOSITS IN A GLOBAL TECTONIC CONTEXT 6.1 Introduction 6.2 Patterns in the distribution of mineral deposits 6.3 Continental growth rates 6.4 Crustal evolution and metallogenesis 6.5 Metallogeny through time 6.6 Plate tectonics and ore depositsa summary Summary and further reading References Index vi CONTENTS Preface to break the monotony. The staff at Blackwell managed to combine being really nice people with a truly professional attitude, and Ian Francis, Delia Sandford, Rosie Hayden, and Cee Pike were all a pleasure to work with. Dave Coles drafted all the diagrams and I am extremely grateful for his forebearance in dealing amiably with a list of figures that seemingly did not end. Several people took time to read through the manuscript for me and in so doing greatly improved both the style and content. They include John Taylor (copyediting), Judith Kinnaird and Dave Waters (Introduction), Grant Cawthorn (Chapter 1), Philip Candela (Chapter 2), Franco Pirajno (Chapter 3), Michael Meyer (Chapter 4), John Parnell and Harold Reading (Chapter 5), and Mark Barley, Kevin Burke, and John Dewey (Chapter 6). The deficiencies that remain, though, are entirely my own. A particularly debt of gratitude is owed to David Rickard, who undertook the onerous task of reviewing the entire manuscript; his lucid comments helped to eliminate a number of flaws and omissions. Financial support for this project came from BHP Billiton in London and the Geological Society of South Africa Trust. My colleagues at Wits were extremely supportive during my long absences, and I am very grateful to Spike

The Rahaba layered intrusion in the Southern Eastern Desert of Egypt is mainly composed of pyroxene hornblende-,
and hornblende gabbros. It hosts thick Fe–Ti oxide ore layers that are composed of titanomagnetite
with subordinate ilmenite and magnetite. To understand the petrogenesis of the Fe–Ti rich gabbroic rocks, the
nature of their parent high-Fe primitive mantle melts and condition of Fe–Ti oxide layer formation, we obtained
new mineral chemistry and whole-rock major and trace element compositions. The geochemical characteristics
of the gabbroic rocks resemble those of picro-basalts, suggesting generation from picritic basaltic-like melts of
tholeiitic affinity. Their high-Fe-Ti-Mg nature (TiO2, ~1.91 wt%; MgO, ~11.0 wt%; Fe2O3, ~14 wt%) probably
indicates elevated mantle potential temperatures due to upwelling of hot asthenospheric mantle. Rare earth
elements (REEs) of clinopyroxene show flat patterns with depletion in LREEs, similar to those of the host gabbros
and picritic basaltic lava, suggesting a mantle origin for their parental melts. Moreover, clinopyroxene compositions
show differentiation trends similar to low-pressure igneous intrusions, and reveal a rift-related origin.
Chemistry of plagioclase (An45–62), clinopyroxene (Wo38.4–45.3, En39.9–43, Fs14–19.3; Mg#: 0.71–0.92) and olivine
(Fo56–80) shows wide compositional ranges due to variable degrees of crystal fractionation. The calculated
equilibrium temperature for the Rahaba Fe-Ti-rich gabbros is mainly 820–1000 ◦C, at pressure below 5 kbar,
reflecting depth of rock solidification of <15 Km. These rocks show both subduction-like and rift-related
geochemical signatures comparable to other post-collisional layered intrusions in the Arabian-Nubian Shield.
The low average Ce/Pb (8.3) and high Ba/Nb (391) ratios together with the enriched large-ion lithophile elements
(Cs, Ba, K and Sr) and depleted high-field strength elements (Th, Nb, Ta and Zr) reflect the contribution
from a preceding subduction event. The lineament map, structural lineament and lineament density map reveal
main WNW-ESE and NW-SE structural trends of the Najd System in the Rahaba area. The Rahaba Fe–Ti rich
gabbroic intrusion was likely formed by initial impact of a mantle plume head with Fe-rich streaks at the base of
metasomatized lithospheric mantle during an extensional phase associated with activity of the Najd-related
strike-slip faults, at the end of the East African Orogeny. The resultant mantle-derived melt compositions and
Najd-related structures possibly controlled the distribution of Fe–Ti ore deposits during this Orogeny. The
Rahaba gabbroic intrusion was emplaced during post-collisional extension after slab break-off and lithospheric
delamination following collision of accreted island-arcs with the Saharan Metacraton.

Rare metals (Nb, Ta, Y, Zr, Sn, U, W and REE) are economically important and new supplies need to be found. In order to understand Neoproterozoic rare metal granites of the Arabian-Nubian Shield (ANS), six samples from five rare-metal mineralized alkali feldspar granites, syenogranites and granodiorite from the Central and SE Desert of Egypt were studied for zircon U-Pb ages and O-isotopic compositions as well as whole-rock Sr-and Nd-and alkali feldspar Pb-isotopic compositions. These are transitional between I-type and A-type granites, mostly high-K calc-alkaline, peraluminous granites with gullwingshaped REE patterns and strongly negative Eu anomalies. Four granites gave mantle-like zircon δ 18 O V-SMOW between 4.2 and 5.96‰ and yielded ages of 628-633 Ma. This is about when subduction-related magmatism began to be replaced by collisionrelated magmatism. Igla Ahmr granites are older, formed at 691.7-678.9 Ma with δ 18 O V-SMOW c. 5.95‰. All have positive initial ε Nd values (+3.3 to +6.9) typical for mantle and juvenile crust. Pb isotopic compositions are unusually radiogenic compared with unmineralized ANS granitic rocks. The data indicate similar magmatic sources for ANS mineralized and unmineralized granites. Exploration for other rare-metal mineralized granites in the ANS should focus on bodies with similar characteristics.

Based on results of study of the regional position, chemical composition of ores, fluid inclusions, and age relationships between mineralization and igneous rocks, we propose a geological and genetic model for the formation of gold mineralization of the Zaderzhninskoe deposit. Mineralization is located in the tectonic node of the intersection of two regional structures in the supraintrusive zone of a latent granitoid pluton among the terrigenous rocks of the Verkhoyansk complex, which are regionally metamorphosed to the greenschist facies. The sequential deposition of three types of mineralization-Au-quartz (including early low-gold Au-As and late productive Au-Pb-Zn mineralization), Au-rare-metal, and Au-silver-has been established. The Au-Bi (Te) assemblage contains native bismuth, bismuthinite, hedleyite, Bi sulfotellurides, gustavite group minerals, and secondary minerals-Bi oxides and Bi tellurites with low-grade gold. Hg-containing electrum and kustelite, Ag-Sb and Ag-Pb-Sb sulfosalts, stutzite, Te-Pb-containing canfieldite, freibergite, and Au and Ag sulfides are indicator minerals of the Au-Ag (Sb) assemblage. Ore formation occurred at temperatures from 90 to 340 ºC, with the participation of lowly and moderately concentrated solutions with CO 2 ± CH 4 ± N 2 gas phase. A decrease in temperature from Au-quartz mineralization (200-220 ºC) to the late epithermal one (160 ºC) and a slight increase in the concentration of solutions (up to 10 wt.% NaCl equiv.) have been established. The deposit resulted from the intricate multistage geodynamic evolution of the South Verkhoyansk region. Ore-forming processes are associated with the evolution of magmatic objects. Dating of igneous rocks yields the following ages: diorites-130-137 Ma (Rb-Sr), spessartites-126 ± 3 Ma (Rb-Sr), and kersantites-115 ± 1.7 Ma (Ar/Ar). Early concordant Au-quartz (Au-As) mineralization of the deposit is comparable with metamorphic-related Au-quartz veins of the Yur-Bular type, and its age is taken as >137 Ma. The time of formation of Au-quartz (Au-Pb-Zn) mineralization is estimated at 123.5 ± 1.6 Ma (Ar/Ar) and is coeval with the time of intrusion of the Early Cretaceous granitoids of the South Verkhoyansk region. The imposed low-temperature mineralization undoubtedly has a younger age. Its formation was followed by the successive deposition of Au-rare-metal mineralization at the final stage of formation of granitoid plutons (~120 Ma) and Au-Ag mineralization in the period 100 ± 5 Ma, i.e., the time of formation of late-stage granodiorite-granite intrusions.

An unusual hydrothermal alteration scheme was presented for chevkinite-(Ce) from the White Tundra pegmatite (2656 ± 5 Ma), Keivy massif, Kola Peninsula. Pb-CO2-rich fluids initially removed REE and Y from the chevkinite-(Ce), with enrichment in Pb and U. PbO abundances reaching 17.35 wt%. Continued alteration resulted in the altered chevkinite-(Ce) being progressively transformed to a Pb-Ti-Fe-Si phase, which proved, upon EBSD analysis, to be almost totally amorphous. Pb enrichment was accompanied by a loss of LREE, especially La, relative to HREE, and the development of strong positive Ce anomalies. A notably U-rich aeschynite-(Y), with UO2 values ≤7.67 wt%, crystallized along with the chevkinite-(Ce). Aeschynite-(Y) with a lower UO2 value (3.91 wt%) and bastnäsite-(Ce) formed during alteration. The formation of bastnäsite-(Ce) rather than cerussite, which might have been expected in a high Pb-CO2 environment, is ascribed to the fluids being acidic.

The Keivy alkali granite-nepheline syenite complex, Kola Peninsula, NW Russia, contains numerous associated Zr-REE-Y-Nb occurrences and deposits, formed by a complex sequence of magmatic, late-magmatic, and post-magmatic (including pegmatitic, hydrothermal, and metasomatic) processes. The REE-rich lithologies have abundant (some of economic importance) and diverse britholite group minerals. The REE and actinides distribution in host rocks indicates that the emanating fluids were alkaline, with significant amounts of F and CO2. From chemical studies (REE and F variations) of the britholites the possible fluid compositions in different lithologies are proposed. Fluorbritholite-(Y) and britholite-(Y) from products of alkali granite (mineralized granite, pegmatite, quartzolite) formed under relatively high F activity in fluids with low CO2/H2O ratio. The highest F and moderate CO2 contents are characteristic of fluid from a mineralized nepheline syenite, resulting in crystallization of ...

, spine1 systems have been explained on the basis of the molecular field theory, after taking into account superexchange, double exchange, Dzyaloshinsky-Moriya exchange as well as biquadratic exchange. From the Anderson-Kanamori theory of superexchange, the transfer integrals and from the molecular orbital model, the admixture and the covalent-mixing parameters as well as the electron spin transfer coefficients have been estimated.

The results of extensive experimental and theorettcal studies of magnetic properties for CuCr2X 4 (X = S, Se) spinel compounds are summarized. They concern the magnetometric, neutron and X-ray diffracuon, X-ray photoelectron spectra and nuclear magnetic resonance studies, made in the different ranges of temperature. All the experimental data were interpreted wlthiu the framework of an tonic model (however, the chemical bonds between anions and cations have there the mixed mine-covalent character, the ionic contribution ~s predominant). This work demonstrates the temperature dependence of the valence of the Cr and Cu ions m CuCr,Se 4 compound. It has been proved that the Lotgering and the Goodenough models, assuming a valence stability of these ions, fail. Evidence for the temperature dependence of the valence for these cations has been presented also in the case of the Znl_,Cu,Cr2Se ~ solid solutions. These systems may be classified as "tnter-atomic" intermediate valent to be d~stinguished from valence fluctuating "intra-atom]c" mixed vaient systems.

Zircon grains are reasonably ubiquitous in river banks and beach placers as detrital minerals, including along the ~1700 km long Indian east coast, from Odisha state to the state of Kerala. Zircons from beach placers and river banks located along the eastern part of Odisha, India, were studied using LA-ICP-MS in order to delineate their geochemical characteristics. Hf (mean = 11270 ppm) and Y (mean = 1064 ppm) were the two most abundant trace elements found within zircon grains as compared to other trace elements. The abundance of uranium was observed to be 2–4 times larger than that of thorium. Zircon overgrowths formed in equilibrium with a partial melt and were similar to magmatic zircon in terms of the high Y, Hf and P content, steep heavy-enriched REE pattern, positive Ce anomaly and negative Eu anomaly. The average low Th/U ratio of the studied zircon grains distinguished them from the magmatic ones. The REE present in zircon grains was restricted to high-grade metamorphic eve...

The Ren gold prospect, Elko County, Nevada, is in the northern part of the Carlin trend, two kilometers northwest of the recently-discovered, high-grade Purple Vein deposit. The Ren area is underlain mainly by Paleozoic sedimentary rocks, consisting of limestone, calcareous siltstone, and mudstone of the eastern (carbonate) assemblage, overlain in thrust contact by chert, quartzite, and mudstone of the western (siliceous) assemblage. Cretaceous (?) granodiorite porphyry and hornblende porphyry dikes have intruded the sedimentary rocks along north-striking faults. Three stages of mineralization include a pre-or syntectonic base metal-barite assemblage, a middle stage of Agand Sb-rich jasperoid, and a late Au-rich stage responsible for the potentially economic mineralization at the prospect. The latter two stages of alteration and mineralization were focused along steep eastdipping faults and dikes, and the nearly flat-lying contact between lower massive limestone and laminated calcareous siltstone. Mineralization is present between 380 and 500 m below the surface. Alteration includes decalcification and weak silicification in siltstone, and formation of massive jasperoid in the upper part of the limestone unit. Alteration of dikes is mainly sericite-quartz-pyrite, with late pyrite-quartz-kaolinite. The element suite characteristic of Au-stage mineralization includes Au, As, and Hg with minor Ag and Hg; Ag and Sb are most enriched in the earlier jasperoid event. Haloes of As and Hg extend at least 80 m above the Au mineralization, but no anomalies are present at the surface. Gold anomalies are more widespread, and extend to shallower depths, but are less coherent.

Within these trials were treated results of 288 lithogeochemistry and 362 soil samples. Gold, silver and arsenic were the elements selected for the geochemical interpretation in the Surfer software package. Gold anomalies in lithogeochemical samples ranged from 0.31 up to 19 ppm Au while in the soil samples concentrations ranged 1-5 ppm Au. Silver anomaly values, in soil samples, were within the range 0.34 ÷ 19 ppm Ag and for arsenic values were 4÷2001 ppm As. Mercury, antimony and thallium were enclosed within this geochemical study, but however they were not taken into consideration for the Surfer helped interpretation. The 3D model displays the hypsometric difference in the distribution of gold of 170 m, from level 730 m up to level 900 m. Lithogeochemitry map of gold shows linear orientation of anomalous concentrations probably due to deposition of gold along the fault structures of northwest direction.

The productive ore mineralization within the Kozuf metallogenic area, mainly, has been related to the Alpine metallogenic epoch while spatial and temporal has been spread during the Cretaceous stage and Pliocene period. During the Cretaceous metallogeny were formed several iron and nickel deposits related to the redeposited lateritic crusts developed over the Jurassic ultrabasic rocks (dunite, harzburgite, lherzolite). The most important lateritic crust mineralizations were determined in the Rzanovo ore deposit (40 Mt so 1.1% Ni), as well as occurrences at Studena Voda, Gradiste, Rakle and Nikodin. During the late Alpine metallogenic epoch in the Kozuf area were formed polymetallic Cu-Au-Sb-As-Tl-Pb-Zn mineralizations in Alshar and Dudica deposits, related to the Pliocene magmatism (6.0-1.8 Ma) and ring-radial structures related to that particular volcanism. Carlin-type gold (> 1 g/t Au), was determined in parts of the Alshar deposit.

Calculated ore-bearing coefficient in the Vrshnik ore body was 0.78%, meaning that within the ore body boundaries only 22% of mass is not mineralized somehow, which is highly compatible with remaining three ore bodies within the Buchim porphyry copper mine. The calculated value of variation coefficient (V) has shown value of 70% that is in the range of 43-100%, which displays that this ore body belongs to the third group of deposits with uneven mineralization. An average copper, gold and silver concentrations were determined as 0.305% Cu, 0.18g/t Au and 0.91 g/t Ag, respectively. Minimal economic content (MEC) within the Vršnik ore body, as represent of this kind of mineralization, was determined as 0.160% Cu. In similar manner was calculated the lowest copper boundary (cutoff grade), which have shown value of 0.138% Cu and thus allowing certain decrease of contents in exploited ore. Also, there were calculated so called copper monometal values, which included influence of the present gold and silver in the ore. Calculated copper monometal was set at relatively fair 0.399% Cu that represents solid mainstay for exploitation of copper in these low percentage ores. Calculated ore reserves in this particular ore body were 13 577 267 t of ore with 0.305% Cu, 0.18 g/t Au and 0.91 g/t Ag and increased mine life for additional 6 years.

The Kirazlıyayla deposit is one of Pb-Zn (±Cu) deposits associated with andesitic volcanism cutting through the metamophics of Karakaya complex. It is a structurally controlled, vein-stockwork style, mesothermal ore deposit. Replacement, brecciation, vein/veinlets, carries, sea-island, and dissemination textures were identified. Pyrite, sphalerite, chalcopyrite, galena, tennantite, and covellite constitute the ore mineral paragenesis. Quartz, calcite and dolomite with kaolinite account for the gangue minerals. Supergene stage is insignificant. The Kirazlıyayla mineralization is a Zn-Pb (±Cu) mineralization hosted by tectonically controlled andesitic volcanism within the Karakaya metamorphics and has common features with the other occurrences in the western Anatolia.

The Dobroe deposit with 10 t gold reserves is one of the gold mines located within the Yenisei Ridge Orogenic Belt. The ore-forming conditions of orogenic gold deposits are have recently been widely discussed. A comprehensive study of fluid inclusions revealed that the Dobroe gold deposit was formed by water–carbon dioxide and carbon dioxide–hydrocarbon fluids within a temperature range of 180 to 360 °C, a pressure range of 0.8 to 1.3 kbar, and a salinity range of 1.5 to 15.0 wt.% (NaCl-equiv.). Gas chromatography–mass spectrometry showed that ore-forming fluids consisted of H2O, CO2, hydrocarbons, nitrogenated, sulfonated, and chlorinated compounds. The distribution patterns of δ13C in fluid inclusions (−11.3‰–−3.6‰) and δ34S in sulfides (1.9‰–17‰) of the Dobroe deposit indicate a crustal source for ore-bearing fluids.

Oxyvanite has been identified as an accessory mineral in Cr-V bearing quartz-diopside meta morphic rocks of the Slyudyanka Complex in the southern Baikal region, Russia. The new mineral was named after constituents of its ideal formula (oxygen and vanadium). Quartz, Cr-V bearing tremolite and micas, calcite, clinopyroxenes of the diopside-kosmochlor-natalyite series, Cr bearing goldmanite, eskolaite-karelianite dravite-vanadiumdravite, V bearing titanite, ilmenite, and rutile, berdesinskiite, schreyerite, plagioclase, scapolite, barite, zircon, and unnamed U-Ti-VCr phases are associated minerals. Oxyvanite occurs as anhedral grains up to 0.1-0.15 mm in size, without visible cleavage and parting. The new mineral is brittle, with conchoidal fracture. Observed by the naked eye, the mineral is black, with black streak and resinous luster. The microhardness (VHN) is 1064-1266 kg/mm 2 (load 30 g), and the mean value is 1180 kg/mm 2. The Mohs hardness is about 7.0-7.5. The calculated density is 4.66(2) g/cm 3. The color of oxyvanite is pale cream in reflected light, without internal reflections. The measured reflectance in air is as follows (

Ba-Ti-V(Cr) oxides along with Ti-V(Cr) oxides in one of the samples. One of these oxides turned out to be the rare mineral ankangite Ba(Ti,V,Cr) 8 O 16 (the first finding in Russia), while another, a new mineral species from the derbylite group with the ideal formula V 8 Ti 6 [Ba(Si 2 O)]O 28 , described in this study. The name batisivite was given after the major cations in the ideal formula (Ba, Ti, Si, V). MODE OF OCCURRENCE AND PHYSICAL PROPERTIES The Cr-V-bearing metamorphic rocks of the Slyudyanka Complex have been characterized many times,

The K/Ar age of ignimbrite is 2.8-3.0 Ma; the age of granodiorite porphyry is 2.5 ± 0.2 Ma (Borsuk, 1979) or 2.7 Ma (Ar-Ar method) (Lipman et al., 1993; Gazis et al., 1995). Large xenoliths of marmorized and skarnified limestone, dolomite, mudstone, and siltstone were found on the eroded surface of the volcanic edifice close to the crest of a small ridge between the Lakargi and Vorlan peaks. The size of carbonate xenoliths ranges from a few meters to a few tens of meters; mud stone and siltstone xenoliths reach a few meters across (Gazeev et al., 2006). Carbonate xenoliths have been studied in more detail. Marble cores and skarn enve lopes are distinguished. These xenoliths were repeat edly described in connection with new minerals found therein: calcioolivine γ Ca 2 SiO 4 (Zadov et al., 2008), lakargiite CaZrO 3 (Galuskin et al., 2008), chegemite Ca 7 (SiO 4) 3 (OH) 2 (Galuskin et al., 2009), kumtyubeite Ca 5 (SiO 4) 2 F 2 (Galuskina et al., 2009), bitikleite

The Eastern Black Sea Region of Turkey contains over 400 massive (Kuroko-type) and vein-type Cu-Pb-Zn deposits. The Inler Yaylasi lead-zinc deposits are typical examples of the vein type and have been economically mined for 15 years. Three ore veins were identified along E-W-trending fault zones, hosted by extensively altered, Upper Cretaceous volcano-sedimentary rocks. A Tertiary granitoid intrusion occurs near the area of mineralization. The ore veins contain sphalerite, galena, and minor amounts of pyrite, chalcopyrite, fahlore, chalcocite, and covellite as ore minerals, with quartz and calcite as gangue minerals. Fluid-inclusion studies show that the salt composition, salinity, and temperature of the hydrothermal fluids changed during various mineralization episodes. The temperature and salinity of the fluid were high (average temperature of 312.9°C and average salinity of 7.0% NaCl equiv.), and the fluid contained CaCl 2 , MgCl 2 , and NaCl during an early episode of mineralization characterized by quartz crystallization. During the sulfide crystallization, temperature and salinity were lower (average temperature of 272.0°C and average salinity of 4.0% NaCl equiv.), and the salts were mainly MgCl 2 , NaCl, and FeCl 2. During subsequent mineralization episodes, temperature and salinity were still lower (average temperature 138.5 °C and average salinity 2.6% NaCl equiv.), and the salt content was dominated by NaCl, Na 2 CO 3 , NaHCO 3 , Na 2 SO 4 , and KCl. Oxygen-and hydrogen-isotope results (δ 18 O; +4.2 to +6.7 ‰ VSMOW and δ D;-83.0 to-59.0 ‰ VSMOW) suggest that magmatic water dominated the ore fluid. It is possible, however, that small amounts of meteoric water and/or formation water of meteoric origin were also involved. This isotopic composition may also be the result of interaction of meteoric water with magmatic rocks, as has been suggested for other deposits in the eastern Black Sea region. The decrease in temperature and salinity of the fluid and the increase in δ 18 O values of the water from 1725 to 1803 m levels also supports the hypothesis that these deposits formed where upwelling hot fluids met cold surfical fluids.

A new mineral, hilarionite, ideally (SO 4)(AsO 4)(OH) ⋅ 6H 2 O, has been found in the Hilar ion Mine, Agios Konstantinos, Kamariza, Lavrion district, Attiki Prefecture, Greece. It was formed in the oxidation zone of a sulfide rich orebody in association with goethite, gypsum, bukovskyite, jarosite, melan terite, chalcanthite, allophane, and azurite. Hilarionite occurs as light green (typically with an olive or grayish tint) to light yellowish green spherulites (up to 1 mm in size) and bunches of prismatic to acicular "individu als" up to 0.5 mm long that are in fact near parallel or divergent aggregates of very thin, curved fibers up to 0.3 mm long and usually lesser than 2 μm thick. The luster is silky to vitreous. The Mohs' hardness is ca. 2. Hilarionite is ductile, its "individuals" are flexible and inelastic; fracture is uneven or splintery. D(meas) = 2.40(5), D(calc) = 2.486 g/cm 3. IR spectrum shows the presence of arsenate and sulfate groups and H 2 O mol ecules in significant amounts. The Mössbauer spectrum indicates the presence of Fe 3+ at two six fold coor dinated sites and the absence of Fe 2+. Hilarionite is optically biaxial (+), α = 1.575(2), γ = 1.64(2), 2V is large. The chemical composition (electron microprobe, average of 7 point analyses; H 2 O determined by modified Penfield method) is as follows, wt %: 0.03 MnO, 0.18 CuO, 0.17 ZnO, 33.83 Fe 2 O 3 , 0.22 P 2 O 5 , 18.92 As 2 O 5 , 22.19 SO 3 , 26.3 H 2 O, total is 101.82%. The empirical formula calculated on the basis of 15 O is: Cu 0.01 Zn 0.01) Σ1.92 [(SO 4) 1.24 (AsO 4) 0.74 (PO 4) 0.01 ] Σ1.99 (OH) 1.01 ⋅ 6.03H 2 O. The X ray powder diffraction data show close structural relationship of hilarionite and ka kite, (AsO 4) 2 ⋅ 7H 2 O. Hilarionite is mono clinic, space group C2/m, Cm or C2, a = 18.53(4), b = 17.43(3), c = 7.56(1) Å, β = 94.06(15)°, V = 2436(3) Å 3 , Z = 8. The strongest reflections in the X ray powder diffraction pattern (d, Å-I[hkl]) are

The K/Ar age of ignimbrite is 2.8-3.0 Ma; the age of granodiorite porphyry is 2.5 ± 0.2 Ma (Borsuk, 1979) or 2.7 Ma (Ar-Ar method) (Lipman et al., 1993; Gazis et al., 1995). Large xenoliths of marmorized and skarnified limestone, dolomite, mudstone, and siltstone were found on the eroded surface of the volcanic edifice close to the crest of a small ridge between the Lakargi and Vorlan peaks. The size of carbonate xenoliths ranges from a few meters to a few tens of meters; mud stone and siltstone xenoliths reach a few meters across (Gazeev et al., 2006). Carbonate xenoliths have been studied in more detail. Marble cores and skarn enve lopes are distinguished. These xenoliths were repeat edly described in connection with new minerals found therein: calcioolivine γ Ca 2 SiO 4 (Zadov et al., 2008), lakargiite CaZrO 3 (Galuskin et al., 2008), chegemite Ca 7 (SiO 4) 3 (OH) 2 (Galuskin et al., 2009), kumtyubeite Ca 5 (SiO 4) 2 F 2 (Galuskina et al., 2009), bitikleite

The In-Abeggui gold deposit is located in the Eastern part of the Laouni terrane (Hoggar, South Algeria). Our studies lead us to distinguish two shape kinds of gold mineralization i/big quartz-tourmaline veins hosted in gabbro-diorite massif; ii/ stockwerk and veins hosted in microgranite-aplite dikes. These felsic rocks are the latest and crosscut all the structures. All is incorporated in the frame of a Neoproterozoic volcano-sedimentary basin. The mineralization is characterized by intensive hydrothermal alteration where microgranite-aplite transformed in quartz-muscovite association (greisen). Mineral association encountered in this deposit is : quartz-tourmaline-muscovite-rutile-topazwolframite-molybdenite-pyrite-arsenopyrite-pyrrhotite-chalcopyrite-bismuthinite-native bismuthgalena-sphalerite-native gold-calcite-dolomite and iron oxides. Yet, In Abeggui is a gold deposit by it characterized by the presence of topaz ± molybdenite ± wolframite linked to greisens stage; as well a...

Incommensurately modulated twin structure of nyerereite Na 1.64 K 0.36 Ca(CO 3) 2 has been first determined in the (3+1)D symmetry group Cmcm(α00)00s with modulation vector q = 0.383a*. Unit-cell values are a = 5.062(1), b = 8.790(1), c = 12.744(1) Å. Three orthorhombic components are related by threefold rotation about [001]. Discontinuous crenel functions are used to describe occupation modulation of Ca and some CO 3 groups. Strong displacive modulation of the oxygen atoms in vertexes of such CO 3 groups is described using x-harmonics in crenel intervals. The Na, K atoms occupy mixed sites whose occupation modulation is described by two ways using either complementary harmonic functions or crenels. The nyerereite structure has been compared both with commensurately modulated structure of K-free Na 2 Ca(CO 3) 2 and with widely known incommensurately modulated structure of γ-Na 2 CO 3 .

The Ntem Complex represents the northwestern margin of Congo Craton in southern Cameroon. It consists mainly of charnockites, TTG suites, potassic grantitoids, minor supracrustal and mafic rocks. The latter include gabbronorite enclave or sill, gabbro and dolerite dykes. The metagabbro are basaltic to andesitic in composition and show geochemical features of low-La Archean tholeiitic basalts, and LREE-depleted (La N /Sm N < 1) akin to modern N-MORB. The doleritic dykes show high TiO 2 /P 2 O 5 (7.50-11.47) and (La/Yb) N ratios, and low Nb\ \Ta values similar to modern intraplate continental basalts and intermediate-La Archean tholeiitic basalt, least affected by contamination from granitic continental crust. The partial melting of low-to high-K mafic rocks of oceanic and continental arc affinity generated the charnockites and low−/medium-pressure TTGs. The potassic granites were formed by partial melting of charnockite or TTG, and inherited many geochemical features of their sources. New LA-ICP-MS U\ \Pb zircon dates suggest that the charnockites and TTG suites formed at 3155-2850 Ma. The gabbro intrusion was dated at 2866 ± 6 Ma. Migmatisation of TTG-gneiss was coeval whit the regional high-grade metamorphism event at 2843 ± 7 Ma. The potassic granites were probably crystallized at~2758 Ma. The garnet-whole rock Sm\ \Nd age of 2744 ± 31 Ma may represent the age of the second anatexis event coeval with D2 deformation. Literature data indicate the disruption or open isotopic systems in the Ntem Complex around 2500-2600 Ma.