Hypogene Alteration And Mineralization In The Dos Pobres Porphyry Cu Au Mo Deposit Safford District Arizona

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Hypogene Alteration And Mineralization In The Dos Pobres Porphyry Cu Au Mo Deposit Safford District Arizona

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Author : Daniel Russin
language : en
Publisher:
Release Date : 2008

Hypogene Alteration And Mineralization In The Dos Pobres Porphyry Cu Au Mo Deposit Safford District Arizona written by Daniel Russin and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with Copper ores categories.

Dos Pobres is unusual among Arizona porphyry deposits in that it is relatively gold- and bornite-rich, and magnetite-bearing and is intimately associated with relatively mafic (quartz monzodiorite-low silica granodiorite) porphyry dikes. Conversely, it has considerably less pyrite and acid alteration than most other Arizona porphyry deposits. These features are like those in many other Au-rich porphyry systems, and they have also stimulated comparisons with andesite-hosted iron-oxide (-Cu-Au) (IOCG) systems such as Candelaria.

Distribution And Styles Of Hypogene Alteration And Mineralization In The Miami Inspiration Porphyry Cu Mo Deposit Globe Miami District Arizona

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Author : Nathan T. Swaim
language : en
Publisher:
Release Date : 2020

Distribution And Styles Of Hypogene Alteration And Mineralization In The Miami Inspiration Porphyry Cu Mo Deposit Globe Miami District Arizona written by Nathan T. Swaim and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with Copper ores categories.

The Miami-Inspiration porphyry Cu-Mo deposit is associated with a Late Cretaceous/Early Paleocene pluton in the southwestern North American porphyry Cu province. Hypogene Cu and Mo mineralization in the Miami-Inspiration deposit is related to porphyritic intrusions of the Schultze Granite (67-61 Ma) and is manifested as vein- and veinlet-hosted and disseminated sulfides in the Schultze Granite and the ~1.7 Ga Pinal Schist. The deposit has been rotated and extended by several generations of mid-Tertiary normal faults which have tilted originally shallower forms of alteration toward the northeast while deeper forms are exposed in the southwest portions of the deposit. Map patterns show that pervasive sulfide-poor potassic alteration (K-feldspar-quartz-biotite ± pyrite) in the southwest and center of the deposit is in contact with sulfide-bearing potassic (K-feldspar-quartz-biotite-chalcopyrite-pyrite) and transitional potassic-sericitic alteration (stable K-feldspar-sericite-chalcopyrite-pyrite) to the north and northeast. Early dark micaceous veins are present in strongly localized pockets in barren potassic alteration, and gray-green sericite veins are present in the sulfide-bearing potassic zone. Sericitic alteration (quartz-sericite-pyrite) postdates and overprints potassic and transitional potassic-sericitic alteration, as sericite pervasively replaces hydrothermal K-feldspar. Propylitic alteration (chlorite-magnetite-epidote-actinolite-calcite) is observed in the northeastern portions of the deposit, while coarse muscovite (“greisen”) alteration (muscovite-quartz-K-feldspar ± pyrite ± chalcopyrite) overprints potassic and barren potassic alteration and mineralization in the southwestern parts of the system. Copper mineralization (chalcopyrite and minor bornite) is mostly concentrated in the sulfide-bearing potassic, transitional potassic-sericitic, and sericitic alteration zones. Vein-hosted molybdenum mineralization in quartz + molybdenite veins and veinlets is common where potassic alteration is overprinted by sericitic alteration. These interpreted alteration and mineralization patterns are similar to other quartz monzodioritic-granitic porphyry Cu-Mo systems in the Globe-Miami district and the southwestern porphyry province.

Evolution Of La Caridad Porphyry Copper Deposit Sonora And Geochronology Of Porphyry Copper Deposits In Northwest Mexico

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Author :
language : en
Publisher:
Release Date : 2005

Evolution Of La Caridad Porphyry Copper Deposit Sonora And Geochronology Of Porphyry Copper Deposits In Northwest Mexico written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with categories.

In order to improve our understanding of poorly studied Mexican Porphyry Copper Deposits in the SW regional metallogenetic province, a detailed study of the hydrothermal fluid evolution of La Caridad porphyry copper-molybdenum deposit, and its connection to a high sulfidation epithermal deposit, was performed using oxygen, hydrogen and sulfur stable isotopes combined with fluid inclusion studies. In addition, U-Pb and Re-Os geochronology from La Caridad, Milpillas and El Arco porphyry deposits were performed to constrain the timing of mineralization and magmatism in northwest Mexico. Uranium-lead zircon ages from La Caridad suggest a short period of magmatism, between 55.5 and 53.0 Ma. Re-Os molybdenite ages from potassic and phyllic hydrothermal veins yielded identical ages within error, 53.6" 0.3 Ma and 53.8" 0.3 Ma, respectively. Four stages of hypogene alteration and mineralization are recognized at La Caridad porphyry copper deposit. The isotopic composition of the water in equilibrium with hydrothermal alteration minerals is consistent with highly evaporated lacustrine waters mixed with magmatic waters or vapor separated from magmatic fluids, however, sulfur isotopes and fluid inclusions data support the lacustrine-magmatic water hypotesis. Milpillas porphyry copper deposit in the Cananea Mining District, yielded a crystallization age of 63.9" 1.3 Ma. Two Re-Os molybdenite ages yielded an identical age of 63.1" 0.4 Ma, Suggesting a restricted period of mineralization. Re-Os data indicate that mineralization in Cananea District, spanned 4̃ m.y. in three discrete pulses at 5̃9 Ma, 6̃1 Ma and 6̃3Ma. El Arco porphyry copper deposit, Baja California, Mexico, yielded a Middle Jurassic crystallization age (U-Pb) of 164.7" 6.7 Ma and a Re-Os mineralization age of 164.1" 0.4 Ma and not 1̃00 Ma as previously determinated. Porphyry copper deposits in Mexico range in age from 164 Ma to 54 Ma and the mineralization in Sonora state ocurred in two different periods, but magmatism overlaps in space and time.

The Geology And Geochemistry Of The Haquira East Porphyry Copper Deposit Of Southern Peru

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Author : Federico Cernuschi Rodilosso
language : en
Publisher:
Release Date : 2015

The Geology And Geochemistry Of The Haquira East Porphyry Copper Deposit Of Southern Peru written by Federico Cernuschi Rodilosso and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with Copper ores categories.

This dissertation is informally divided into three major sections. In the first section (Chapter 2) I use data from field mapping, isotopic geochronology, whole rock geochemistry and trace element concentrations in zircons to examine the petrology, geochemistry and ages of the Haquira East porphyry copper deposit of southern Peru. In the second section (Chapters 3 - 6) I investigate the timing, temperature, zonation and lifespan of the magmatic-hydrothermal alteration and Cu-Mo mineralization by applying field mapping, whole rock geochemistry, petrography, geothermometry, spectral, X-ray and cathodoluminiscense imaging of rock samples. The timescales of the magmatic-hydrothermal system was constrained by isotopic dating, diffusion of titanium in quartz and the novel approach of oxygen diffusion via [delta]18O of quartz analyzed by secondary ion mass spectrometry. These data are also used construct cross-sections and 3D models. In the final section (Chapter 7) I describe the production and evaluation of a calibration for portable X-ray spectrometers that could potentially be applied to further investigate porphyry copper deposits. Haquira East is a moderate grade porphyry copper-molybdenum-gold deposit (688 Mt ore at 0.59 wt. % Cu, containing 4.7 Mt Cu, 37,000 t Mo and 0.9 M oz Au) in the Eocene-Oligocene Andahuaylas-Yauri porphyry belt of southern Peru. Based on a Re/Os age of molybdenite, the copper and molybdenum mineralization and hydrothermal alteration at Haquira East formed at ~33.85 Ma. These ores are associated with dominantly granodioritic intrusions that range from 34.5 to 33.5 Ma in age and represent some of the youngest intrusions of the Andahuaylas-Yauri batholith between 40 and 32 Ma. In this study, new U-Pb zircon ages of these intrusions ages were determined via laser ablation inductively coupled mass spectroscopy (LA-ICP-MS) and sensitive high resolution ion microprobe in reverse geometry (SHRIMP-RG). At Haquira East, the regional Eocene-Oligocene shortening of the Incaic orogeny resulted in the folding of Jurassic-Cretaceous meta-sedimentary rock into the northwest-trending and northeast-overturned Tocone syncline that is associated with northwest-striking and southwest-dipping thrust faults. The magmatism was synchronous with the deformation and began with the ~34.5 Ma andesitic to dacitic Lahuani sills and was followed by the ~34.2 to 33.5 Ma Haquira granodiorite stock and the slightly younger, narrow and subvertical Haquira porphyry dikes of similar composition. Several sets of Haquira porphyry dikes were emplaced synchronously with the porphyry copper and molybdenum mineralization, veining and K-silicate hydrothermal alteration. At the waning stages of the magmatism (~33.5), the dacitic Pararani porphyry dikes were emplaced along a north-south strike and closely followed in time with D veins, sericitic halos and sericitically-altered hydrothermal breccias. Whole-rock trace element modeling indicates that the Haquira East magmas originated in a garnet-bearing basaltic-andesite to andesite zone of melt-assimilation-storage-hybridization (MASH) in the lower crust below ~25 km depth. Andesite melts from the MASH zone were injected into an inferred granodiorite magma chamber at ~10km depth beneath Haquira East, where the oxidized and water-rich magma fractionated hornblende and small amounts of plagioclase, together with traces of titanite, apatite, zircon and magnetite. Intrusions sourced in this chamber have enrichments in Sr/Y (>60) and V/Sc (>12), depletions in the light rare earth elements (REE) and high mid-REE/heavy-REE ratios inherited from melts derived from the MASH zone where garnet is residual. Similarly, the intrusions that were emplaced closely in time with the mineralization have high Eu[subscript N]/Eu[subscript N]* (0.4 to 0.8) and Ce[subscript N]/Ce[subscript N]* (200 to 5000) in zircon compared to older intrusions (LA-ICP-MS, and SHRIMP-RG) further evidencing the high oxidation state and water content of the magma. New core logging observations, ICP-MS whole rock geochemical data and short wave infrared spectroscopy data document the sequence and spatial distribution of veins, hydrothermal alteration zones and Cu-Mo-bearing sulfide ore zones and are summarized in cross-sections and three-dimensional models. From oldest to youngest, the sequence of veins consists of biotite veins/micro-breccias, aplite dikes, deep quartz (DQ) veins, actinolite veins with plagioclase halos and epidote veins, early dark micaceous (EDM) halos with bornite-chalcopyrite, Cu-sulfide±quartz veinlets with chalcopyrite and/or bornite, banded molybdenite-quartz (BMQ) veins, B-type quartz-bornite-chalcopyrite veins, D-type pyrite-quartz-sericite veins with sericitic halos, and fractures with green and white intermediate argillic halos containing mixtures of illite-smectite-chlorite-kaolinite ± pyrite. The areas with the highest density of EDM halos constitute the high-grade copper ore. Scanning electron microscopy imaging (QEMSCAN) have been used to identifiy mineralogy, textures and zoning of hydrothermal alteration zones. The EDM halos are formed by hydrothermal biotite, muscovite, K-feldspar, with rare quartz and corundum replacing magmatic plagioclase and hornblende and carry up to 10-15 volume % disseminated bornite and chalcopyrite. Later BMQ veins host the high-grade molybdenum ore, whereas late B veins contribute both copper and molybdenum to the ores. The copper ore shell forms a continuous high-grade ore zone (>0.5 wt. %) in the Haquira stock, but is lower grade where it projects into the relatively non-reactive meta-sedimentary, mostly quartzite, wall rock, likely as a result of a limited supply of iron to enable copper-iron sulfide precipitation. In contrast, molybdenite mineralization forms a roughly symmetric shell overlapping both the stock and quartzite with an axis of symmetry located along the southwest flank of the Haquira granodiorite stock. The abundance of EDM halos, lack of A veins and the dearth of unmixed fluid inclusion assemblages in quartz veins and prescense of two phase (liquid + vapor) fluid inclusions (P>1.5 kbar) suggest that Haquira East was emplaced at significant depths. The emplacement depth of Haquira is estimated at ~10 km, at greater depth than shallower and outcropping Acojasa intrusion to the south, emplaced at ~ 8 km according to hornblende barometry (~2.0 ± 0.5 kb). The veining, hydrothermal alteration and mineralization formed at this depth magmatic hydrothermal fluid was released from an inferred magmatic cupola, hydro-fractured the wall rock and depressurized from ~3 kb at lithostatic pressure to >1.2 kb at close to hydrostatic pressure without unmixing into a vapor and brine phase. The temperature evolution of the magmatic-hydrothermal system was estimated by mineral phase equilibria and the application of different geothermometers. For TitaniQ geothermometry, Ti-in-quartz of veins and dikes was measured by electron microprobe (EMP) and LA-ICP-MS (1 ppm to > 100 ppm) on samples that were previously imaged by secondary electron microscope cathodoluminescense, Temperatures were also estimated through Ti-in-zircon (2 ppm to 13 ppm, via SHRIMP-RG), Ti-in-biotite (~1.0 to 2.3wt.%, via EMP) and the [delta]34S compositions of pyrite-anhydrite and chalcopyrite-anhydrite pairs (-1.4 [per mil] to -0.1[per mil] and 7.5 [per mil] to 10.2 [per mil] respectively). Porphyry dikes, aplites and DQ veins formed first between ~720oC and 650oC. Copper was introduced later in EDM halos at ~500oC and was followed by molybdenite in BMQ veins at ~650oC during a thermal reversal. A second stage of copper and molybdenum was introduced in B veins at ~550°C. Late D veins with pyrite and sericite formed first at ~450oC and later at ~350oC.

Genesis Of The El Salvador Porphyry Copper Deposit Chile And Distribution Of Epithermal Alteration At Lassen Peak California

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Author : Robert George Lee
language : en
Publisher:
Release Date : 2009

Genesis Of The El Salvador Porphyry Copper Deposit Chile And Distribution Of Epithermal Alteration At Lassen Peak California written by Robert George Lee and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with Copper ores categories.

The El Salvador porphyry copper deposit in the Indio Muerto district of northern Chile has been geologically investigated for more than 60 years and provides one of the best bases for understanding similar environments of ore formation elsewhere in the world. Fourteen new zircon U/Pb isotopic ages obtained via in situ SHRIMP-RG analysis are here coupled with previous geological studies to allow refinement of the timing of Eocene porphyry magma emplacement responsible for copper and molybdenum mineralization that occurs in several ore bodies within the district. The earliest intrusions are rhyolites that crop out throughout the district, but are more abundant in the north. In contrast, the later granodiorite porphyries were emplaced only in the central and southern parts of the district. Two age periods of mineralization have been documented using zircon U/Pb geochronology. The low grade and small copper deposit at Old Camp in the northern district is associated with a quartz porphyry intrusion that yielded an age of 43.6 ± 0.5 Ma, whereas the main copper molybdenum deposit at Turquoise Gulch is associated with emplacement of the granodioritic L porphyry plug that yielded an age of 42.0 ± 0.5 Ma. The final intrusion is a series of latite porphyry dikes, which post-date ores and yielded a U/Pb zircon age of 41.6 ± 0.5 Ma. Inherited Eocene zircons with ages from ~45 Ma to ~47 Ma are found within younger porphyry intrusions and likely formed via magmatic recycling of older intrusions. Therefore, the zircon U/Pb ages suggest magmatism spanned approximately 5 million years from 47 to 42 Ma, with hydrothermal copper-molybdenum ores dominantly forming during the final stages of porphyry emplacement. Geochemical analyses by XRF, ICP-MS, electron microprobe and laser-ablation ICP-MS define a wide range of major, minor and trace element contents for the Eocene porphyry intrusions within the district. The early rhyolite and quartz porphyry intrusions have rare earth contents with strong negative europium anomalies and relatively low Sr/Y and Sm/Yb ratios consistent formation via fractional crystallization of plagioclase-rich mineral assemblages from more mafic parental melts. The granodiorite porphyries have no europium anomalies and a wide range of Sr/Y and Sm/Yb ratios that support an origin via fractional crystallization of garnet, hornblende ± titanite, and minor plagioclase from an andesitic parental melt. The granodiorite intrusions at M Gulch - Copper Hill are ~1 m.y. older than and have less evolved trace element ratios than the younger granodiorite intrusions associated with the main mineralization event. The evolving Eocene intrusions are the result of lower to middle crust melts ascending to mix with silica-rich differentiated melts derived from fractional crystallization of older andesitic magmas. Progressive decrease of Eu/Eu* ratios in the zircons with decreasing age gives direct evidence in support of the hypothesis that the main ore mineralization is directly related to the evolution of the upper crustal magma reservoir to progressively more oxidized conditions. A second goal of this study was to document the mineralogy and zonation of altered wall rock at Lassen National Volcanic Park in northern California, in order to understand the pressure, temperature, fluid composition, and epithermal processes along the southern flank of Lassen Peak. Extensive epithermal wall rock alteration occurs along the southern flank of the Cascadia volcano and includes both active and fossil geothermal systems. Geologic mapping coupled with mineral identification using a portable infrared spectrometer and X-ray diffraction outline several hydrothermal systems within the park. Currently active, steam-heated acid sulfate alteration is characterized by kaolinite, alunite, opal, and cristobalite with accessory iron sulfates. The active hydrothermal zones are proximal to thermal pools and fumaroles at Sulphur Works, Pilot Pinnacle, Little Hot Springs Valley, and Bumpass Hell. At least three fossil systems occur within andesite lavas and flow breccias of the eroded Pleistocene Brokeoff Volcano. Intermediate argillic alteration occurs at higher elevations on the flanks of the eroded volcano and is characterized by mixed layer illite-smectite, quartz, pyrite, and albite. Propylitic alteration occurs within the eroded lower elevations of Little Hot Springs Valley and is characterized by chlorite, calcite, quartz, pyrite, illite, albite, and rare epidote. Also present to a lesser extent is an advanced argillic alteration defined by pyrophyllite, dickite, alunite, kaolinite, and quartz formed at Pilot Pinnacle.

Stable Isotope Investigation Of A Hydrothermal Alteration System

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Author : Lihua Zhang
language : en
Publisher:
Release Date : 2000

Stable Isotope Investigation Of A Hydrothermal Alteration System written by Lihua Zhang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2000 with Copper ores categories.

Typical porphyry-type Cu-Mo mineralization predates and underlies the well-known Main Stage polymetallic veins of the Butte district, Montana. This thesis presents the first systematic study of the isotopic characteristics of the pre-Main Stage K-silicate and sericitic wallrock alteration related to the porphyry Cu-Mo stage. Oxygen and hydrogen isotopic compositions were obtained from hydrous and other silicate minerals of sixty-two samples from the unaltered host rock and ores: four Butte Quartz Monzonite; seven samples from K-silicate alteration; twenty samples of K-silicate alteration affected by late argillic alteration; and twenty-seven samples of gray-sericite alteration. These data support current porphyry Cu-Mo models that the associated hydrothermal fluids that produced pre-Main Stage K-silicate and gray sericite were dominantly magmatic in origin. Butte differs from other porphyry Cu-Mo districts because the widespread Main Stage or younger argillic alteration dominated by meteoric water ([delta]D = -100 to -120%) has partly to totally reset the hydrogen isotopic compositions of hornblende (D = -45 to -l26%) and biotite ([delta]D -61 to -l35%) in the fresh Butte Quartz Monzonite host rock, biotite (D = -47 to -131%o) of the early high temperature K-silicate alteration assemblages, and locally reset the [delta]D values ( -25 to -1 l7%o) of sericite (muscovite) of gray-sericite alteration assemblages. The effect of argillic alteration on these minerals was to produce D-depleted isotopic composition ([delta]D = -80 to -140%). Sulfur isotope analyses have been applied to sulfides and anhydrite from forty-seven samples selected from deep drill cores. These include sulfate-sulfide assemblages in veinlets associated with K-silicate alteration selvages and slightly younger quartz-pyrite veinlets associated with gray-sericite alteration selvages. The K-silicate and gray-sericite sulfide values (34S = +0.4 to +4.7 %) presented here are similar to those of Main Stage sulfides reported previously and suggest a conventional "magmatic" value ([delta]345 about 2 %o) for Butte sulfide-sulfur in the hydrothermal fluid. However, the anhydrite from the K-silicate alteration yields a much heavier 634S value (+ 12.9 %o), therefore, total sulfur (& 4Szs %) of the early K-silicate assemblage was likely as heavy as 10 per mil, suggesting a possible crustal component to this relatively oxidized system.

Physiochemical Characteristics During Potassic Alteration Of The Porphyry Copper Deposit At Ajo Arizona

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Author : Veronica Feliciano UyTana
language : en
Publisher:
Release Date : 1983

Physiochemical Characteristics During Potassic Alteration Of The Porphyry Copper Deposit At Ajo Arizona written by Veronica Feliciano UyTana and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1983 with Copper ores categories.

Potassium metasomatism is a widespread alteration type in porphyry copper deposits and is often spatially associated with hypogene sulfide ore formation. At Ajo, potassic alteration composes the dominant alteration type and is spatially, and to some extent, temporally, associated with chalcopyrite and bornite mineralization. Physiochemical conditions prevailing during potassic alteration thus describe a significant portion of the hydrothermal ore-forming process. Studies of fractures, fluid inclusions in quartz, and structural and compositional characteristics of K-feldspar, all in the potassic alteration zone at Ajo, indicate that: fracturing was strongest during potassic alteration and sulfide deposition, pressure were at approximately 650 bars, temperatures started a a minimum of 580°C, continued through 470°C, log aK+/aH+ changed from 2.6 at 580°C to 3.2 at 470°C, log aNa/aH+ changed from 2.7 at 580°C to 3.8 at 470°C, and the ratio aK+/aNa+ radically decreased from 0.8 to 0.3 in this temperature range.

Hydrothermal Alteration And Mineralization Of The Iron Oxide Cu Au Santo Domingo Sur Deposit Atacama Region Northern Chile

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Author : Giancarlo A. Daroch
language : en
Publisher:
Release Date : 2011

Hydrothermal Alteration And Mineralization Of The Iron Oxide Cu Au Santo Domingo Sur Deposit Atacama Region Northern Chile written by Giancarlo A. Daroch and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with Hydrothermal alteration categories.

SDS hydrothermal system resembles others IOCG deposits along the CIB belt and elsewhere, where mineralization took place under relatively oxidizing conditions, under generally sulfur-poor conditions, and likely between 350 and 250°C. Iron oxide minerals exhibit episodic changes between hematite and magnetite dominance, presumably due to a change in temperature or oxygen fugacity. Mineralization is located at a similar stratigraphic level to deposits in the Candelaria-Punta del Cobre district. The stratabound nature of the SDS orebody contrasts with other strongly discordant orebodies, such as Mantoverde and certain deposits in the Candelaria-Punta del Cobre district. In addition, similarities between Chilean manto type Cu ( -Ag) and Santo Domingo Sur deposit are suggested, consistent with the hypothesis that of stratabound Cu ( -Ag) deposits are lower temperature analogues of IOCG systems in the CIB.

Recueil Documentation Sur Mario Sironi

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Author :
language : en
Publisher:
Release Date :

Recueil Documentation Sur Mario Sironi written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on with categories.

Economic Geology

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Author :
language : en
Publisher:
Release Date : 2005

Economic Geology written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with categories.