Prospects, properties and formation of nanogold. Typification of ultrafine (nano) gold-bearing ores. Classification of forms of natural gold exposure presence with aggregation of free nanogold

The mineralogical and compositional characteristics of gold-bearing minerals and the occurrence of gold are not only of great significance to exploring the sources of ore-forming materials and their formation mechanisms but also helpful for designing reasonable beneficiations and smelting schemes and achieving remarkable economic benefits. This paper presents an integrated study on the crystal characteristics, elemental composition and distribution of pyrite (the main gold-bearing minerals), on the basis of electron probe microanalysis (EPMA), scanning electron microscopy (SEM), laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and nano-secondary ion mass spectrometry (NanoSIMS). The occurrence of gold in the Shuiyindong gold deposit and Ashawayi gold deposit has been studied by means of microscopy, SEM, and EPMA images, elemental correlations, S–Fe–As ternary diagrams, logAs–logAu diagrams and Au/As ratios. The gold in pyrite of the Shuiyindong deposit is in the form of nano gold inclusions and lattice gold. The gold in pyrite of the Ashawayi deposit dominantly exists in the form of nano gold inclusions or is present as micro-nano gold particles in the cracks or edges of pyrite, some of which can exist as lattice gold. The ore-forming hydrothermal solution of the Shuiyindong gold deposit is mainly underground hot brine, but it may be reformed by a deep magmatic hydrothermal solution or volcanic-subvolcanic hydrothermal solution. The ore-forming hydrothermal solution of the Ashawayi gold deposit is mainly derived from the metamorphic hydrothermal solution formed during the orogenic process, and the ore-forming process or post-mineralization process may be reformed by the leaching of underground hot brine. Finally, the characteristics of ore-forming fluids and evolution of the two types of deposits are determined via pyrite element surface scanning. This paper shows that micro-nanoscale study of gold-bearing pyrite is of great significance to understanding the gold mineralization process and is worth further study.

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Matter-mineral characteristics of technogene placers – potential sources of precious metals (on the example of the Nizhneselemdzhinsky gold-bearing node of Priamurye, Russia)

Georesursy ◽

10.18599/grs.2019.1.2-14 ◽

2019 ◽

Vol 21 (1) ◽

pp. 2-14 ◽

Cited By ~ 1

Author(s):

Inna V. Kuznetsova ◽

Petr P. Safronov ◽

Natalya V. Moiseenko

Keyword(s):

Precious Metal ◽

Native Gold ◽

Precious Metals ◽

High Standard ◽

Metallic Lead ◽

Additional Information ◽

Mineral Characteristics ◽

Nano Gold ◽

Spoil Heaps ◽

Gold Bearing

Over tens of years of mining and processing of ores and placers of gold in the world a huge amount of wastes originated in the form of spoil heaps and tailing dumps, in which the content of valuable components allow them to be considered a real additional resource of precious metals. The aim of the work was to establish the changes that took place in time in the spoil heaps of gold mining and to determine the prospects of the technogene placers as a potential source of the precious metal. The investigations were carried out with the use of the methods of the analytical raster electron microscopy and mineralogical and atomic-absorption analyses. On the example of the Nizhneselemdzhinsky gold-bearing node of Priamurye we have done the compatative analysis of the mineral and granulometric composition of the original and developed placers. It is shown that through the technogenesis the mineral composition of the deposits changes including the process of decomposition of the lead and iron minerals with a partial reduction to a native metal. In addition to the native gold in the technogene placers there have been found the following minerals with a high content of the precious metal: rutile, monazite, magnetite, metallic lead, galena, ilmenite, and zircon. The content of free gold in dumps is 190 mg/m3 in the average. The main amount of it (about 83%) consists of the fine gold (< 0.5 mm). We have studied the chemical composition of the native gold and associated rocks. It has been established that the gold has a multiphase composition. The phases are for the most part the gold amalgams and have two-, three-, and four-component compositions (Au-Hg, Au-Ag-Hg, Au-Hg-Pb, Au-Ag-Hg-Pb). About 30% of gold of the technogene placers have a high standard of fineness (~980‰). Almost all native gold is in close intergrowths with the rock-forming matrix of different composition: hydroalumosilicates, oxides, and hydroxides of Fe, Mn, and Pb, highly carbonaceous and carbon-bearing formations, and so on. Under the action of the physicochemical and biochemical process in the technogene placers different transformations of the native gold take place: purification at the expense of the silver evacuation; decomposition of the minerals-concentrators of gold; precipitation of micro- and nano-gold at the geochemical barriers with the formation of the so-called “new” gold (from nanoformations to micro- and macroforms). Through the operation of the technogene placers one should take into account the fact that the ore minerals in them have high concentrations of heavy metals and radioactive elements, and the gold has a complicated multiphase and multicomponent composition, and ¾ of it is amalgamated. The data obtained give the additional information for the elaboration of technologies for the development of the prospective gold-bearing technogene placers.

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Note on the spectral classification of carbon stars in the photographic infrared region

Symposium - International Astronomical Union ◽

10.1017/s0074180900053080 ◽

1966 ◽

Vol 24 ◽

pp. 21-23

Author(s):

Y. Fujita

Keyword(s):

Infrared Region ◽

Spectral Classification ◽

Carbon Stars

We have investigated the spectrograms (dispersion: 8Å/mm) in the photographic infrared region fromλ7500 toλ9000 of some carbon stars obtained by the coudé spectrograph of the 74-inch reflector attached to the Okayama Astrophysical Observatory. The names of the stars investigated are listed in Table 1.

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Fluids and hydrothermal alteration assemblages in a Devonian gold-bearing hot-spring system, Rhynie, Scotland

Transactions of the Royal Society of Edinburgh Earth Sciences ◽

10.1017/s0263593303000221 ◽

2003 ◽

Vol 94 (04) ◽

pp. 309 ◽

Cited By ~ 1

Keyword(s):

Hydrothermal Alteration ◽

Hot Spring ◽

Spring System ◽

Gold Bearing

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Diagnostic Value of Electron Microscopy in Soft Tissue Tumors

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100068096 ◽

1970 ◽

Vol 28 ◽

pp. 220-221

Author(s):

Gerald Fine ◽

Azorides R. Morales

Keyword(s):

Cardiac Myxoma ◽

Osteogenic Sarcoma ◽

Diagnostic Value ◽

Soft Tissue Tumors ◽

Amelanotic Melanoma ◽

Growth Patterns ◽

Light Microscopic Level ◽

Mesenchymal Tumors ◽

Good Agreement

For years the separation of carcinoma and sarcoma and the subclassification of sarcomas has been based on the appearance of the tumor cells and their microscopic growth pattern and information derived from certain histochemical and special stains. Although this method of study has produced good agreement among pathologists in the separation of carcinoma from sarcoma, it has given less uniform results in the subclassification of sarcomas. There remain examples of neoplasms of different histogenesis, the classification of which is questionable because of similar cytologic and growth patterns at the light microscopic level; i.e. amelanotic melanoma versus carcinoma and occasionally sarcoma, sarcomas with an epithelial pattern of growth simulating carcinoma, histologically similar mesenchymal tumors of different histogenesis (histiocytoma versus rhabdomyosarcoma, lytic osteogenic sarcoma versus rhabdomyosarcoma), and myxomatous mesenchymal tumors of diverse histogenesis (myxoid rhabdo and liposarcomas, cardiac myxoma, myxoid neurofibroma, etc.)

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Ultrastructure of mesotheliomas

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100110775 ◽

1984 ◽

Vol 42 ◽

pp. 98-101

Author(s):

Irving Dardick

Keyword(s):

Electron Microscopy ◽

Latent Period ◽

Spindle Cell ◽

Spindle Cell Sarcoma ◽

Metastatic Adenocarcinoma ◽

Cell Sarcoma ◽

Cytological Features ◽

Industrial Use ◽

Degree Of Differentiation

With the extensive industrial use of asbestos in this century and the long latent period (20-50 years) between exposure and tumor presentation, the incidence of malignant mesothelioma is now increasing. Thus, surgical pathologists are more frequently faced with the dilemma of differentiating mesothelioma from metastatic adenocarcinoma and spindle-cell sarcoma involving serosal surfaces. Electron microscopy is amodality useful in clarifying this problem.In utilizing ultrastructural features in the diagnosis of mesothelioma, it is essential to appreciate that the classification of this tumor reflects a variety of morphologic forms of differing biologic behavior (Table 1). Furthermore, with the variable histology and degree of differentiation in mesotheliomas it might be expected that the ultrastructure of such tumors also reflects a range of cytological features. Such is the case.

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Interpreting HVEM of muscle-cell impulse networks

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010012103x ◽

1992 ◽

Vol 50 (1) ◽

pp. 126-127

Author(s):

Paul DeCosta ◽

Kyugon Cho ◽

Stephen Shemlon ◽

Heesung Jun ◽

Stanley M. Dunn

Keyword(s):

Structural Analysis ◽

Muscle Cell ◽

Electron Micrographs ◽

Relative Size ◽

Automatic Classification ◽

Nerve Fibers ◽

Analysis Algorithm ◽

Structural Networks

Introduction: The analysis and interpretation of electron micrographs of cells and tissues, often requires the accurate extraction of structural networks, which either provide immediate 2D or 3D information, or from which the desired information can be inferred. The images of these structures contain lines and/or curves whose orientation, lengths, and intersections characterize the overall network.Some examples exist of studies that have been done in the analysis of networks of natural structures. In, Sebok and Roemer determine the complexity of nerve structures in an EM formed slide. Here the number of nodes that exist in the image describes how dense nerve fibers are in a particular region of the skin. Hildith proposes a network structural analysis algorithm for the automatic classification of chromosome spreads (type, relative size and orientation).

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Dual stain kit for the microscopic gram classification of ocular infection bacteria

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100147089 ◽

1993 ◽

Vol 51 ◽

pp. 248-249

Author(s):

Jacob S. Hanker ◽

Dale N. Holdren ◽

Kenneth L. Cohen ◽

Beverly L. Giammara

Keyword(s):

Contact Lenses ◽

Ocular Infection ◽

Gram Negative Bacteria ◽

Gram Negative ◽

Gram Staining ◽

Ocular Infections ◽

Different Types ◽

Culture Positive ◽

Increased Susceptibility

Keratitis and conjunctivitis (infections of the cornea or conjunctiva) are ocular infections caused by various bacteria, fungi, viruses or parasites; bacteria, however, are usually prominent. Systemic conditions such as alcoholism, diabetes, debilitating disease, AIDS and immunosuppressive therapy can lead to increased susceptibility but trauma and contact lens use are very important factors. Gram-negative bacteria are most frequently cultured in these situations and Pseudomonas aeruginosa is most usually isolated from culture-positive ulcers of patients using contact lenses. Smears for staining can be obtained with a special swab or spatula and Gram staining frequently guides choice of a therapeutic rinse prior to the report of the culture results upon which specific antibiotic therapy is based. In some cases staining of the direct smear may be diagnostic in situations where the culture will not grow. In these cases different types of stains occasionally assist in guiding therapy.

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