Journal articles: 'Invisible gold'

1

Volkov, A. V., and A. A. Sidorov. "Invisible gold." Herald of the Russian Academy of Sciences 87, no. 1 (January 2017): 40–48. http://dx.doi.org/10.1134/s1019331617010051.

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2

Asadi, H. H., J. H. L. Voncken, and M. Hale. "Invisible gold at Zarshuran, Iran." Economic Geology 94, no. 8 (December 1, 1999): 1367–74. http://dx.doi.org/10.2113/gsecongeo.94.8.1367.

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3

Ciobanu, Cristiana L., Nigel J. Cook, Allan Pring, Joël Brugger, Leonid V. Danyushevsky, and Masaaki Shimizu. "‘Invisible gold’ in bismuth chalcogenides." Geochimica et Cosmochimica Acta 73, no. 7 (April 2009): 1970–99. http://dx.doi.org/10.1016/j.gca.2009.01.006.

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4

Large, Ross R., and Valeriy V. Maslennikov. "Invisible Gold Paragenesis and Geochemistry in Pyrite from Orogenic and Sediment-Hosted Gold Deposits." Minerals 10, no. 4 (April 9, 2020): 339. http://dx.doi.org/10.3390/min10040339.

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LA-ICPMS analysis of pyrite in ten gold deposits is used to determine the precise siting of invisible gold within pyrite, and thus the timing of gold introduction relative to the growth of pyrite and related orogenic events. A spectrum of invisible gold relationships in pyrite has been observed which suggests that, relative to orogenic pyrite growth, gold introduction in some deposits is early at the start of pyrite growth; in other deposits, it is late toward the end of pyrite growth and in a third case, it may be introduced at the intermediate stage of orogenic pyrite growth. In addition, we report a distinct chemical association of invisible gold in pyrite in the deposits studied. For example, in the Gold Quarry (Carlin type), Mt Olympus, Macraes and Konkera, the invisible gold is principally related to the arsenic content of pyrite. In contrast, in Kumtor and Geita Hill, the invisible gold is principally related to the tellurium content of pyrite. Other deposits (Golden Mile, Bendigo, Spanish Mountain, Witwatersrand Carbon Leader Reef (CLR)) exhibit both the Au-As and Au-Te association in pyrite. Some deposits of the Au-As association have late orogenic Au-As-rich rims on pyrite, which substantially increase the value of the ore. In contrast, deposits of the Au-Te association are not known to have Au-rich rims on pyrite but contain nano- to micro-inclusions of Au-Ag-(Pb-Bi) tellurides.

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MacKenzie, Doug, Dave Craw, and Craig Finnigan. "Lithologically controlled invisible gold, Yukon, Canada." Mineralium Deposita 50, no. 2 (June 12, 2014): 141–57. http://dx.doi.org/10.1007/s00126-014-0532-5.

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Bustos Rodriguez, H., D. Oyola Lozano, Y. A. Rojas Martínez, G. A. Pérez Alcázar, and A. G. Balogh. "Invisible gold in Colombian auriferous soils." Hyperfine Interactions 166, no. 1-4 (November 3, 2006): 605–11. http://dx.doi.org/10.1007/s10751-006-9327-0.

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7

Vikentyev, Ilya, Olga Vikent’eva, Eugenia Tyukova, Maximilian Nikolsky, Julia Ivanova, Nina Sidorova, Dmitry Tonkacheev, et al. "Noble Metal Speciations in Hydrothermal Sulphides." Minerals 11, no. 5 (May 3, 2021): 488. http://dx.doi.org/10.3390/min11050488.

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A significant part of the primary gold reserves in the world is contained in sulphide ores, many types of which are refractory in gold processing. The deposits of refractory sulphide ores will be the main potential source of gold production in the future. The refractory gold and silver in sulphide ores can be associated with micro- and nano-sized inclusions of Au and Ag minerals as well as isomorphous, adsorbed and other species of noble metals (NM) not thoroughly investigated. For gold and gold-bearing deposits of the Urals, distribution and forms of NM were studied in base metal sulphides by laser ablation-inductively coupled plasma mass spectrometry and by neutron activation analysis. Composition of arsenopyrite and As-pyrite, proper Au and Ag minerals were identified using electron probe microanalysis. The ratio of various forms of invisible gold—which includes nanoparticles and chemically bound gold—in sulphides is discussed. Observations were also performed on about 120 synthetic crystals of NM-doped sphalerite and greenockite. In VMS ores with increasing metamorphism, CAu and CAg in the major sulphides (sphalerite, chalcopyrite, pyrite) generally decrease. A portion of invisible gold also decreases —from ~65–85% to ~35–60% of the total Au. As a result of recrystallisation of ores, the invisible gold is enlarged and passes into the visible state as native gold, Au-Ag tellurides and sulphides. In the gold deposits of the Urals, the portion of invisible gold is usually <30% of the bulk Au.

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Spry, P. G., and S. E. Thieben. "The distribution and recovery of gold in the Golden Sunlight gold-silver telluride deposit, Montana, U.S.A." Mineralogical Magazine 64, no. 1 (February 2000): 31–42. http://dx.doi.org/10.1180/002646100549111.

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AbstractThe gold balance in an ore deposit where the ore is treated by cyanide is the sum of the ‘visible gold’ that is amenable to cyanidation and ‘visible gold’ and the ‘invisible gold’, which are not amenable to cyanidation. Petrographic analyses, electron and ion microprobe as well as scanning electron microscope studies of ore from the Golden Sunlight deposit, Montana, suggest that periods of relatively poor gold recoveries are primarily due to the presence of inclusions, <25 µm in size, of native gold, petzite, calaverite, buckhornite and krennerite. These are encapsulated in cyanide insoluble grains of pyrite, chalcopyrite and tennantite and are present in the tailings. This contribution probably accounts for 3–25% of the unrecoverable gold processed during the life of the mine. Minor amounts (6–7%) of ‘invisible gold’, as indicated by ion microprobe studies and the presence of up to 5% ‘visible gold’ in buckhornite, which is rare in nature, appears to account for the remainder of the gold budget.

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Li, Chang-Ping, Jun-Feng Shen, Sheng-Rong Li, Yuan Liu, and Fu-Xing Liu. "In–Situ LA-ICP-MS Trace Elements Analysis of Pyrite and the Physicochemical Conditions of Telluride Formation at the Baiyun Gold Deposit, North East China: Implications for Gold Distribution and Deposition." Minerals 9, no. 2 (February 22, 2019): 129. http://dx.doi.org/10.3390/min9020129.

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The Baiyun gold deposit is located in the northeastern North China Craton (NCC) where major ore types include Si-K altered rock and auriferous quartz veins. Sulfide minerals are dominated by pyrite, with minor amounts of chalcopyrite, sphalerite and galena. Combined petrological observations, backscattered electron image (BSE) and laser ablation analysis (LA-ICP-MS) have been conducted on pyrite to reveal its textural and compositional evolution. Three generations of pyrite can be identified—Py1, Py2 and Py3 from early to late. The coarse-grained, porous and euhedral to subhedral Py1 (mostly 200–500 μm) from the K-feldspar altered zone is the earliest. Compositionally, they are enriched in As (up to 11541 ppm) but depleted in Au (generally less than 10 ppm). The signal intensity of Au is higher than background values by two orders of magnitude and shows smooth spectra, indicating that invisible gold exists as homogeneously or nanoscale-inclusions in Py1. Anhedral to subhedral Py2 grains (generally ranging 500–1500 μm) coexist with other sulfides such as chalcopyrite, sphalerite and galena in the early silicification stage (gray quartz). They have many visible gold grains and contain little amounts of invisible Au. Notably, visible gold has an affinity with micro-fractures formed due to late deformation, implying that native gold may have resulted from mobilization of preexisting invisible gold in the structure of Py2 grains. Subsequently Py3 occurs as very fine-grained disseminations of euhedral crystals (0.05–1 mm) in late silicification stage (milky quartz) and coexists with tellurides (e.g. petzite, calaverite and hessite). They contain the highest level of invisible gold with positive correlations between Au-Ag-Te. In the depth profiles of Py3, the smooth Au spectra mirror those of Te with high intensities, revealing that gold occurred as homogeneously/nanoscale-inclusions and submicroscopic Au-bearing telluride inclusions in pyrite grains. The high Te and low As in Py3, combined with high Au content, imply that invisible gold can be efficiently scavenged by Te. Abundant tellurides (petzite, calaverite and hessite) have been recognized in auriferous quartz veins. Lack of symbiosis sulfides with the tellurium assemblages indicates crystallization under low fS2 and/or high fTe2 conditions and coincides with the result of thermodynamic calculations. High and markedly variable Co (from 0.24 to 2763 ppm, average 151.9 ppm) and Ni (from 1.16 to 4102 ppm, average 333.1 ppm) values suggest that ore-forming fluid may originate from a magmatically-derived hydrothermal system. Combined with previous geochronological data, the textural and compositional evolution of pyrite indicates that the Baiyun gold deposit has experienced a prolonged history of mineralization. In the late Triassic (220,230 Ma), the magmatic hydrothermal fluids, which had affinity with the post-collisional extensional tectonics on the NCC northern margin, caused initial gold enrichment. Then, as a result of deformation or the addition of new hydrothermal fluids, visible gold-rich Py2 was formed. The upwelling of mantle–derived magma brought in a lot of Te-rich ore-forming hydrothermal fluids during the peak of the destruction of the NCC (~120 Ma). Amount of visible/invisible gold and Au-Ag-Te mineral assemblages precipitated from these mineralized fluids when the physical and chemical conditions changed.

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10

Yang, Meizhi, Quan Wan, Xin Nie, Suxing Luo, Yuhong Fu, Ping Zeng, and Wenqi Luo. "Quantitative XPS characterization of “invisible gold” in Carlin-type gold ores through controlled acid erosion." Journal of Analytical Atomic Spectrometry 36, no. 9 (2021): 1900–1911. http://dx.doi.org/10.1039/d1ja00102g.

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Quantitative XPS analysis of “invisible gold” in Carlin-type gold ores was accomplished, which revealed Au concentration, percentages of Au+ and Au0, and Au NP size. An acid etching step was demonstrated to be the key to enhancing Au signal in XPS.

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Lee, Jong Ju, and Cheon Young Park. "The Recovery of Invisible Gold Using Filter Paper." Journal of the Korean Society of Mineral and Energy Resources Engineers 56, no. 4 (August 1, 2019): 315–25. http://dx.doi.org/10.32390/ksmer.2019.56.4.315.

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12

Reich, Martin, Stephen L. Chryssoulis, Artur Deditius, Carlos Palacios, Alejandro Zúñiga, Magdalena Weldt, and Macarena Alvear. "“Invisible” silver and gold in supergene digenite (Cu1.8S)." Geochimica et Cosmochimica Acta 74, no. 21 (November 2010): 6157–73. http://dx.doi.org/10.1016/j.gca.2010.07.026.

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13

Shimada, Nobutaka, Tomoki Nakamura, Yasuo Morinaga, and Yoshihito Shikama. "Invisible Gold from the Hishikari Epithermal Gold Deposit, Japan: Implication for Gold Distribution and Deposition." Resource Geology 55, no. 2 (June 2005): 91–100. http://dx.doi.org/10.1111/j.1751-3928.2005.tb00231.x.

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14

Sun, Si-Chen, Liang Zhang, Rong-Hua Li, Ting Wen, Hao Xu, Jiu-Yi Wang, Zhi-Qi Li, Fu Zhang, Xue-Jun Zhang, and Hu Guo. "Process and Mechanism of Gold Mineralization at the Zhengchong Gold Deposit, Jiangnan Orogenic Belt: Evidence from the Arsenopyrite and Chlorite Mineral Thermometers." Minerals 9, no. 2 (February 25, 2019): 133. http://dx.doi.org/10.3390/min9020133.

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The Zhengchong gold deposit, with a proven gold reserve of 19 t, is located in the central part of Jiangnan Orogenic Belt (JOB), South China. The orebodies are dominated by NNE- and NW- trending auriferous pyrite-arsenopyrite-quartz veins and disseminated pyrite-arsenopyrite-sericite-quartz alteration zone, structurally hosted in the Neoproterozoic epimetamorphic terranes. Three stages of hydrothermal alteration and mineralization have been defined at the Zhengchong deposit: (i) Quartz–auriferous arsenopyrite and pyrite; (ii) Quartz–polymetallic sulfides–native gold–minor chlorite; (iii) Barren quartz–calcite vein. Both invisible and native gold occurred at the deposit. Disseminated arsenopyrite and pyrite with invisible gold in them formed at an early stage in the alteration zones have generally undergone syn-mineralization plastic-brittle deformation. This resulted in the generation of hydrothermal quartz, chlorite and sulfides in pressure shadows around the arsenopyrite and the formation of fractures of the arsenopyrite. Meanwhile, the infiltration of the ore-forming fluid carrying Sb, Cu, Zn, As and Au resulted in the precipitation of polymetallic sulfides and free gold. The X-ray elements mapping of arsenopyrite and spot composition analysis of arsenopyrite and chlorite were carried out to constrain the ore-forming physicochemical conditions. The results show that the early arsenopyrite and invisible gold formed at 322–397 °C with lgf(S2) ranging from −10.5 to −6.7. The crack-seal structure of the ores indicates cyclic pressure fluctuations controlled by fault-valve behavior. The dramatic drop of pressure resulted in the phase separation of ore-forming fluids. During the phase separation, the escape of H2S gas caused the decomposition of the gold-hydrosulfide complex, which further resulted in the deposition of the native gold. With the weakening of the gold mineralization, the chlorite formed at 258–274 °C with lgf(O2) of −50.9 to −40.1, as constrained by the results from mineral thermometer.

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15

Palenik, Christopher S., Satoshi Utsunomiya, Martin Reich, Stephen E. Kesler, Lumin Wang, and Rodney C. Ewing. "“Invisible” gold revealed: Direct imaging of gold nanoparticles in a Carlin-type deposit." American Mineralogist 89, no. 10 (October 2004): 1359–66. http://dx.doi.org/10.2138/am-2004-1002.

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16

Mao, Shuihe. "Characterization of occurence and distribution of invisible gold in ore by EPMA." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 2 (August 12, 1990): 246–47. http://dx.doi.org/10.1017/s0424820100134831.

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Owing to the invisibility of ultramicron gold (invisible gold) in “Carlin type” gold ore, it is extremely difficult to investigate its occurrence and distribution by conventional determinative means.EPMA has been proved to be very powerful instrument for doing research on this subject because it has advantages of high space resolution, nondestructive,getting quantitative analysis results and observing various kinds of images continuously with same equipment etc.The unoxidized ore sample is selected from drill cuttings at a “Carl in type” gold mine in Southwest China with gold tenor of 31.02 g/t and weighs 2438g. The operating conditions of EPMA are: accelerating voltage 25kV, beam current 1×10-8 A, beam diameter about 1 μm. AuLα but not AuMα is preferably chosen as analysed x-ray line, because AuMα1 (5.840A) is overlapping with the 3rd order line of FeKα (5.812A) to some extent and iron is the main component of pyrite matrix. According to the expression of detection limit(CDL ), the calculated value of CDL under the circumstances is 0.038%.

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17

Mao, Shuihe. "Characterization of Occurrence and Distribution of Invisible Gold in Ore by EPMA." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 2 (August 12, 1990): 544–45. http://dx.doi.org/10.1017/s0424820100136325.

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Owing to the invisibility of ultramicron gold (invisible gold) in “Carl in type” gold ore, it is extremely difficult to investigate its occurrence and distribution by conventional determinative means.EPMA has been proved to be very powerful instrument for doing research on this subject because it has advantages of high space resolution, nondestructive,getting quantitative analysis results and observing various kinds of images continuously with same equipment etc.The unoxidized ore sample is selected from drill cuttings at a “Carlin type” gold mine in Southwest China with gold tenor of 31.02 g/t and weighs 2438g. The operating conditions of EPMA are: accelerating voltage 25kV, beam current 1×l0-8 A, beam diameter about 1 μm. AuLα but not AuMα is preferably chosen as analysed x-ray line, because AuMα 1 (5.840Å) is overlapping with the 3rd order line of FeKα (5.812Å) to some extent and iron is the main component of pyrite matrix. According to the expression of detection limit(CDL ), the calculated value of CDL under the circumstances is 0.038%.

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18

Wang, Yan, Shu Gong, Dashen Dong, Yunmeng Zhao, Lim Wei Yap, Qianqian Shi, Tiance An, Yunzhi Ling, George P. Simon, and Wenlong Cheng. "Self-assembled gold nanorime mesh conductors for invisible stretchable supercapacitors." Nanoscale 10, no. 34 (2018): 15948–55. http://dx.doi.org/10.1039/c8nr04256j.

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19

Morishita, Y., N. Shimada, and K. Shimada. "Invisible gold and arsenic in pyrite from the high-grade Hishikari gold deposit, Japan." Applied Surface Science 255, no. 4 (December 2008): 1451–54. http://dx.doi.org/10.1016/j.apsusc.2008.05.131.

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No, Sang-Gun, Maeng-Eon Park, Bong-Chul Yoo, and Seung-Han Lee. "Genesis of Carbonate Breccia Containing Invisible Gold in Taebaeksan Basin, South Korea." Minerals 10, no. 12 (December 3, 2020): 1087. http://dx.doi.org/10.3390/min10121087.

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The Yemi breccia developed and is distributed within the Paleozoic carbonate rock (Maggol Formation) in the central part of the Taebaeksan Basin, South Korea. Explanation for the genesis of the Yemi breccia has been controversial. We investigated the petrological and mineralogical properties of the breccia and the matrix materials at 60 outcrops. The Yemi breccia is divided into crackle, mosaic, and chaotic breccias based on morphology. In addition, these are divided into blackish, reddish, grayish, and white to pinkish matrix breccias according to the materials of the matrix. Quartz, calcite, pyrite, hematite (after pyrite), and minor epidote, chlorite, and opaque materials mainly comprise the matrix materials. The pyrite grains from the Yemi breccia can be divided into two types based on the mineral texture: diagenetic and hydrothermal. We analyzed the chemistry of pyrite and hematite (after pyrite) from the Yemi breccia with an electron probe X-ray microanalyzer (EPMA). Invisible gold was detected within the pyrite grains by EPMA and disseminated micron-sized isolated gold particles were discovered by backscattered electron (BSE) images. The texture of Au-bearing pyrite and gold particles in the Yemi breccia is especially well matched with pyrite and gold from the Shuiyindong Carlin-type hydrothermal gold deposits, China. Therefore, we suggest an important role of hydrothermal fluid in karstification within the Paleozoic carbonate rock.

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Malyutina, A. V., Yu O. Redin, A. S. Gibsher, and V. P. Mokrushnikov. "SPATIOTEMPORAL AND GENETIC RELATIONSHIPS OF GOLD ORE AND MERCURY-ANTIMONY MINERALIZATION AT THE HG-SB-GOLD-BEARINGCHAUVAI DEPOSIT (KIRGHIZIA): GEOLOGY, MINERALOGY OF ORES AND FEATURES OF HYDROTHERMAL-METASOMATIC PROCESSES." Geology and mineral resources of Siberia, no. 3 (2021): 61–82. http://dx.doi.org/10.20403/2078-0575-2021-3-61-82.

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The Chauvai Hg-Sb deposit is a striking example of combining two contrasting types of mineralization in space: mercury-antimony and gold ones. The article studies the spatial-temporal and genetic relationships of goldore and mercury-antimony mineralization based on a complex of both traditional geological and mineralogicalgeochemical methods, as well as modern instrumental methods for analyzing the mineral composition. Two types of ores with clear structural confinedness have been found at the deposit: a) mercury-antimonic (cinnabarantimonite) ores, associated with jasperoid breccias and manifested exclusively along the tectonic contact of limestone of the Alai section and terrigenous rocks of the Tolubai Formation, and b) gold- sulphide (arsenopyritepyritic) ores, localized in slightly modified carbonate-terrigenous rocks of the Tolubai Formation, overlying the plane of tectonic contact. Ore formation occurred during the following stages: in the late diagenetic, without interruption passing into the catagenetic-hydrothermal, characterized by the formation of gold mineralization, and then in the later hydrothermal-telethermal, characterized by the development of Hg-Sb mineralization. It is established that the main carrying agent of invisible gold (“invisible gold”) in ores is framboidal and idiomorphic pyrite and, especially, its high-arsenic varieties. A set of conducted studies has shown that the gold ore and mercury-antimony mineralization is broken in time and is genetically associated with various hydrothermalmetasomatic processes, and the Chauvai deposit can be classified as a Carlin-like type.

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22

Pokrovski, G. S., C. Escoda, M. Blanchard, D. Testemale, J. L. Hazemann, S. Gouy, M. A. Kokh, et al. "An arsenic-driven pump for invisible gold in hydrothermal systems." Geochemical Perspectives Letters 17 (April 2021): 39–44. http://dx.doi.org/10.7185/geochemlet.2112.

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23

Maddox, L. M., G. Michael Bancroft, M. J. Scaini, and J. W. Lorimer. "Invisible gold; comparison of Au deposition on pyrite and arsenopyrite." American Mineralogist 83, no. 11-12 Part 1 (December 1, 1998): 1240–45. http://dx.doi.org/10.2138/am-1998-11-1212.

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Lee, Jong-Ju, and Cheon-Young Park. "Observability of Invisible Gold using BSE Imagery and Gold Recovery by Microwave-Nitric Acid Leaching." Journal of the Korean Society of Mineral and Energy Resources Engineers 57, no. 1 (February 1, 2020): 1–11. http://dx.doi.org/10.32390/ksmer.2020.57.1.001.

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Ashley, P. M., C. J. Creagh, and C. G. Ryan. "Invisible gold in ore and mineral concentrates from the Hillgrove gold-antimony deposits, NSW, Australia." Mineralium Deposita 35, no. 4 (April 10, 2000): 285–301. http://dx.doi.org/10.1007/s001260050242.

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Pals, D. W., P. G. Spry, and S. Chryssoulis. "Invisible Gold and Tellurium in Arsenic-Rich Pyrite from theEmperor Gold Deposit, Fiji: Implications for Gold Distribution and Deposition." Economic Geology 98, no. 3 (May 1, 2003): 479–93. http://dx.doi.org/10.2113/gsecongeo.98.3.479.

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Schellewald, Barbara. "Gold, Licht und das Potenzial des Mosaiks." Zeitschrift für Kunstgeschichte 79, no. 4 (December 30, 2016): 461–80. http://dx.doi.org/10.1515/zkg-2016-0035.

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Abstract The article focuses on the complex interaction between gold and light in the very specific medium of mosaic in Late Antiquity and Byzantium. Studying the metaphoric qualities of light/gold and its qualitative distinctions in early Christian and Byzantine sources leads us to an understanding of the complex function of gold or golden tesserae in script and images. As gold is understood as light, mosaic seems to be a more or less perfect medium as it is not stable, but dependent on the changing light. The gold ground is transformed in every moment by light. Mosaic can thus be understood as the medium with the greatest capacity to bridge – virtually – the gap between the visible and the invisible divine light.

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Lee, Jong-Ju, Eun-Ji Myung, and Cheon-Young Park. "The Effective Recovery of Gold from the Invisible Gold Concentrate Using Microwave-nitric Acid Leaching Method." Journal of the mineralogical society of korea 32, no. 3 (September 30, 2019): 185–200. http://dx.doi.org/10.9727/jmsk.2019.32.3.185.

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Zhu, Geyunjian Harry, Mohammad Azharuddin, Rakibul Islam, Hassan Rahmoune, Suryyani Deb, Upasona Kanji, Jyotirmoy Das, et al. "Innate Immune Invisible Ultrasmall Gold Nanoparticles—Framework for Synthesis and Evaluation." ACS Applied Materials & Interfaces 13, no. 20 (May 12, 2021): 23410–22. http://dx.doi.org/10.1021/acsami.1c02834.

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Majzlan, Juraj, Martin Chovan, Peter Andráš, Matthew Newville, and Michael Wiedenbeck. "The nanoparticulate nature of invisible gold in arsenopyrite from Pezinok (Slovakia)." Neues Jahrbuch für Mineralogie - Abhandlungen 187, no. 1 (March 1, 2010): 1–9. http://dx.doi.org/10.1127/0077-7757/2010/0156.

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Nkuba, Bossissi, Lieven Bervoets, and Sara Geenen. "Invisible and ignored? Local perspectives on mercury in Congolese gold mining." Journal of Cleaner Production 221 (June 2019): 795–804. http://dx.doi.org/10.1016/j.jclepro.2019.01.174.

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Pals, D. W. "Invisible Gold and Tellurium in Arsenic-Rich Pyrite from the Emperor Gold Deposit, Fiji: Implications for Gold Distribution and Deposition." Economic Geology 98, no. 3 (May 1, 2003): 479–93. http://dx.doi.org/10.2113/98.3.479.

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Barker, S. L. L., K. A. Hickey, J. S. Cline, G. M. Dipple, M. R. Kilburn, J. R. Vaughan, and A. A. Longo. "UNCLOAKING INVISIBLE GOLD: USE OF NANOSIMS TO EVALUATE GOLD, TRACE ELEMENTS, AND SULFUR ISOTOPES IN PYRITE FROM CARLIN-TYPE GOLD DEPOSITS." Economic Geology 104, no. 7 (November 1, 2009): 897–904. http://dx.doi.org/10.2113/gsecongeo.104.7.897.

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Barker, S. L. L., K. A. Hickey, J. S. Cline, G. M. Dipple, M. R. Kilburn, J. R. Vaughan, and A. A. Longo. "UNCLOAKING INVISIBLE GOLD: USE OF NANOSIMS TO EVALUATE GOLD, TRACE ELEMENTS, AND SULFUR ISOTOPES IN PYRITE FROM CARLIN-TYPE GOLD DEPOSITS." Economic Geology 104, no. 7 (November 1, 2009): 897–904. http://dx.doi.org/10.2113/econgeo.104.7.897.

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Genkin, Alexander D., Nikolai S. Bortnikov, Louis J. Cabri, F. E. Wagner, Chris J. Stanley, Yurii G. Safonov, Greg McMahon, J. Friedl, Alexei L. Kerzin, and Gennady N. Gamyanin. "A multidisciplinary study of invisible gold in arsenopyrite from four mesothermal gold deposits in Siberia, Russian Federation." Economic Geology 93, no. 4 (July 1, 1998): 463–87. http://dx.doi.org/10.2113/gsecongeo.93.4.463.

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Silyanov, Sergey A., Anatoly M. Sazonov, Yelena A. Zvyagina, Andrey A. Savichev, and Boris M. Lobastov. "Gold in the Oxidized Ores of the Olympiada Deposit (Eastern Siberia, Russia)." Minerals 11, no. 2 (February 11, 2021): 190. http://dx.doi.org/10.3390/min11020190.

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Native gold and its satellite minerals were studied throughout the 300 m section of oxidized ores of the Olympiada deposit (Eastern Siberia, Russia). Three zones are identified in the studied section: Upper Zone ~60 g/t Au; Middle Zone ~3 g/t Au; Lower Zone ~20 g/t Au. Supergene and hypogene native gold have been found in these zones. Supergene gold crystals (~1 μm), their aggregates and their globules (100 nm to 1 μm) predominate in the Upper and less in Middle Zone. Relic hypogene gold particles (flattened, fracture and irregular morphology) are sporadically distributed throughout the section. Spongiform gold occurs in the Lower Zone at the boundary with the bedrock, as well as in the bedrock. This gold formed in the process of oxidation of aurostibite, leaching of impurities and its further dissolution. Hypogene gold is commonly isolated but for supergene gold typically associated with ferric (hydr)oxides. New formation of gold occurred due to oxidation of sulfide ores and release of “invisible” gold, as well as dissolution, mobilization and re-deposition of metallic hypogene gold. A model for the formation of oxidized ores with the participation of meteoric and low-temperature hydrothermal waters has been proposed.

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Larocque, A. C. L., J. A. Stimac, G. McMahon, J. A. Jackman, V. P. Chartrand, D. Hickmott, and E. Gauerke. "ION-MICROPROBE ANALYSIS OF FeTi OXIDES: OPTIMIZATION FORTHE DETERMINATION OF INVISIBLE GOLD." Economic Geology 97, no. 1 (January 1, 2002): 159–64. http://dx.doi.org/10.2113/gsecongeo.97.1.159.

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38

Sidorova, N. V., V. V. Aristov, A. V. Grigor’eva, and A. A. Sidorov. "“Invisible” Gold in Pyrite and Arsenopyrite from The Pavlik Deposit (Northeastern Russia)." Doklady Earth Sciences 495, no. 1 (November 2020): 821–26. http://dx.doi.org/10.1134/s1028334x20110136.

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39

Pokrovski, Gleb S., Maria A. Kokh, Olivier Proux, Jean-Louis Hazemann, Elena F. Bazarkina, Denis Testemale, Céline Escoda, et al. "The nature and partitioning of invisible gold in the pyrite-fluid system." Ore Geology Reviews 109 (June 2019): 545–63. http://dx.doi.org/10.1016/j.oregeorev.2019.04.024.

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40

Shapiro, B. I., E. S. Kol’tsova, A. G. Vitukhnovskii, D. A. Chubich, A. I. Tolmachev, and Yu L. Slominskii. "Interaction between gold nanoparticle plasmons and aggregates of polymethine dyes: “Invisible” nanoparticles." Nanotechnologies in Russia 6, no. 7-8 (August 2011): 456–62. http://dx.doi.org/10.1134/s1995078011040112.

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41

Wang, Jingjing, Guotao Duan, Yue Li, Guangqiang Liu, Zhengfei Dai, Hongwen Zhang, and Weiping Cai. "An Invisible Template Method toward Gold Regular Arrays of Nanoflowers by Electrodeposition." Langmuir 29, no. 11 (March 6, 2013): 3512–17. http://dx.doi.org/10.1021/la400433z.

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42

Kovalchuk, E. V., B. R. Tagirov, I. V. Vikentyev, D. A. Chareev, E. E. Tyukova, M. S. Nikolsky, S. E. Borisovsky, and N. S. Bortnikov. "“Invisible” Gold in Synthetic and Natural Arsenopyrite Crystals, Vorontsovka Deposit, Northern Urals." Geology of Ore Deposits 61, no. 5 (September 2019): 447–68. http://dx.doi.org/10.1134/s1075701519050039.

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Kovalchuk, E. V., B. R. Tagirov, I. V. Vikentyev, D. A. Chareev, E. E. Tyukova, M. S. Nickolsky, S. E. Borisovsky, and N. S. Bortnikov. "“Invisible” gold in synthetic and natural arsenopyrite crystals (Vorontsovka deposit, Northern Urals)." Геология рудных месторождений 61, no. 5 (November 18, 2019): 62–83. http://dx.doi.org/10.31857/s0016-777061562-83.

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In many types of hydrothermal ore deposits Au occurs in invisible state in most common minerals of the Fe-As-S system. It is supposed that the state of theinvisible Au may beeither non-structural (nano-sized inclusions of metal and its compounds) or chemically bound (isomorphous solid solution). Here we report results of investigation of the state and the concentration range ofinvisible Au in synthetic and natural arsenopyrites FeAsS (Vorontsovka deposit, North Urals, type Carlin). Conditions that favor the formation of Au-bearing arsenopyrite were identified. The synthesis experiments were carried out in Au-saturated system by means of salt flux method with a stationary temperature gradient. The temperature at the cold end of the ampole was 400500С. The chemical composition of arsenopyrite was determined by electron probe microanalysis. The composition of the synthesized arsenopyrite varied within [at.%]: Fe from 32.6 to34.4, As from 30.0 to 36.5, S from 29.4 to36.0. The Au content in arsenopyrite varied from the detection limit ( 45ppm) to 3wt.%. A strong negative correlation between the concentrations of Au and Fe was observed in the synthesized arsenopyrite grains. The slope of the correlation lines corresponds to the formation of the Au-bearing solid solution where Au isomorphically substitutes for Fe at the parameters of the synthesis experiments. In addition, there is a weaker positive correlation between Au and As: higher Au concentrations are characteristic of arsenic-rich compositions (As/S [at.%] 1) and those close to stoichiometric arsenopyrite, whereas in sulfur-rich arsenopyrite the concentration of Au is lower and does not exceed 0.25wt.%. The positive Au-As correlation appears not only on a local level within a single crystal of synthetic and natural arsenopyrite, but is valid on the Vorontsovka deposit scale: As-rich arsenopyrite formed at lower temperature and sulfur fugacity (t= 250370C, logfS2= 1217) contains more Au than the As-poor early arsenopyrite (t= 270400C, logfS2= 79). Comparison of these results with the literature data shows that the positive correlation between the concentrations of Au and As in arsenopyrite and the negative correlation between the concentrations of Au and Fe are the common features of ores of the Carlin-type deposits. We suggest that, in contrast to negative correlation Au-Fe, the positive correlation Au-As cannot be explained in terms of crystal chemistry, but can result from the effect of external factors among which are the difference in composition of ore-forming hydrothermal fluids and the sulfur fugacity.

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44

Li, Nan, Jun Deng, David Groves, and Ri Han. "Controls on the Distribution of Invisible and Visible Gold in the Orogenic Gold Deposits of the Yangshan Gold Belt, West Qinling Orogen, China." Minerals 9, no. 2 (February 4, 2019): 92. http://dx.doi.org/10.3390/min9020092.

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Six orogenic gold deposits constitute the Yangshan gold belt in the West Qinling Orogen. Gold is mostly invisible in solid solution or in the sulfide lattice, with minor visible gold associated with stibnite and in quartz-calcite veins. Detailed textural and trace-element analysis of sulfides in terms of a newly-erected paragenetic sequence for these deposits, together with previously published data, demonstrate that early magmatic-hydrothermal pyrite in granitic dike host-rocks has much higher Au contents than diagenetic pyrite in metasedimentary host rocks, but lower contents of As, Au, and Cu than ore-stage pyrite. Combined with sulfur isotope data, replacement textures in the gold ores indicate that the auriferous ore-fluids post-dated the granitic dikes and were not magmatic-hydrothermal in origin. There is a strong correlation between the relative activities of S and As and their total abundances in the ore fluid and the siting of gold in the Yangshan gold ores. Mass balance calculations indicate that there is no necessity to invoke remobilization processes to explain the occurrence of gold in the ores. The only exception is the Py1-2 replacement of Py1m, where fluid-mediated coupled dissolution-reprecipitation reactions may have occurred to exchange Au between the two pyrite phases.

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Morishita, Yuichi, Napoleon Q. Hammond, Kazunori Momii, Rimi Konagaya, Yuji Sano, Naoto Takahata, and Hirotomo Ueno. "Invisible Gold in Pyrite from Epithermal, Banded-Iron-Formation-Hosted, and Sedimentary Gold Deposits: Evidence of Hydrothermal Influence." Minerals 9, no. 7 (July 19, 2019): 447. http://dx.doi.org/10.3390/min9070447.

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“Invisible gold” in pyrite is defined as an Au solid solution of the pyrite lattice, sub-microscopic Au nanoparticles (NPs) in the pyrite, or other chemisorption complexes of Au. Because the relationship between the Au and As concentrations in pyrite could indicate the genesis of the deposit, the purpose of this study is to assess the micro-analytical characteristics of the Au–As relationship in pyrite from epithermal and hydrothermally affected sedimentary Au deposits by secondary ion mass spectrometry. The Au and As concentrations in pyrite vary from 0.04 to 30 ppm and from 1 to 1000 ppm, respectively, in the high-sulfidation Nansatsu-type epithermal deposits; these concentrations are both lower than those of the low-sulfidation epithermal Hishikari deposit. The Au concentrations in pyrrhotite and pyrite reach 6 and 0.3 ppm, respectively, in the Kalahari Goldridge banded-iron-formation-hosted gold deposit, and Au in pyrrhotite may sometimes exist as NPs, whereas As concentrations in pyrrhotite and pyrite are both low and lie in a narrow range from 6 to 22 ppm. Whether Au is present as NPs is important in ore dressing. The Au and As concentrations in pyrite from the Witwatersrand gold field range from 0.02 to 1.1 ppm and from 8 to 4000 ppm, respectively. The shape of the pyrite grains might prove to be an indicator of the hydrothermal influence on deposits of sedimentary origin, which implies the genesis of the deposits.

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Hazarika, Pranjit, Biswajit Mishra, Sakthi Saravanan Chinnasamy, and Heinz-Juergen Bernhardt. "Multi-stage growth and invisible gold distribution in pyrite from the Kundarkocha sediment-hosted gold deposit, eastern India." Ore Geology Reviews 55 (November 2013): 134–45. http://dx.doi.org/10.1016/j.oregeorev.2013.05.006.

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47

Domengie, Florian, Pierre Morin, and Daniel Bauza. "Finding the Invisible Contaminants in CMOS Image Sensor Pixels: The DCS Technique." EDFA Technical Articles 14, no. 4 (November 1, 2012): 4–11. http://dx.doi.org/10.31399/asm.edfa.2012-4.p004.

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Abstract This article discusses the basic principles of dark current spectroscopy (DCS), a measurement technique that can detect and identify low levels of metal contaminants in CMOS image sensors. An example is given in which DCS is used to determine the concentration of tungsten and gold contaminants in an image sensor and estimate the dark current generated by a single atom of each metal.

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48

Mexias, André S., Gilles Berger, Márcia E. B. Gomes, Milton L. L. Formoso, Norberto Dani, José C. Frantz, and Everton M. Bongiolo. "Geochemical modeling of gold precipitation conditions in the Bloco do Butiá Mine, Lavras do Sul/Brazil." Anais da Academia Brasileira de Ciências 77, no. 4 (December 2005): 717–28. http://dx.doi.org/10.1590/s0001-37652005000400010.

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A geochemical modeling of gold deposition was performed using the EQ3/EQ6 software package using conditions inferred from geological, petrographic, geochemical and fluid inclusion data from the Bloco do Butiá gold mine, Lavras do Sul, RS. Gold in the mine occurs only in the pyrite structure (invisible gold). The pyrite occurs associated with white mica (phengite) in the zone of phyllic alteration. The process of gold deposition showed to be related to temperature and pH decrease. The pH decrease was fundamental to gold deposition by destabilization of sulfur species [Au(HS)2- , HAu(HS)2(0) and Au(HS)0] dissolved in the aqueous solution, being Au(HS)0 the main gold transporting complex. The addition of KCl is hard to accept as cause of gold precipitation because no Cl- was detected in phengite. However, the geochemical mass balance calculation resulted in the gain of some potassium in the zone of phyllic alteration. The precipitation of pyrite (± auriferous) may have been strongly influenced by iron availability resulting from dissolution of ferrous chlorites by the fluids responsible for phengite deposition. The low salinity in quartz grain fluid inclusions from the propylitized wall rock also indicates the little importance of chlorine as gold transporting agent. Sulfur, and not chlorine, compounds must have dominated the gold transporting complexes in the Bloco do Butiá gold area.

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49

Larocque, A. C. L. "ION-MICROPROBE ANALYSIS OF FeTi OXIDES: OPTIMIZATION FOR THE DETERMINATION OF INVISIBLE GOLD." Economic Geology 97, no. 1 (January 1, 2002): 159–64. http://dx.doi.org/10.2113/97.1.159.

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50

Foglesong, D. S. "The Invisible Harry Gold: The Man Who Gave the Soviets the Atom Bomb." Journal of American History 98, no. 1 (June 1, 2011): 245–46. http://dx.doi.org/10.1093/jahist/jar162.

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Journal articles on the topic 'Invisible gold'

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