Khanh Thien gold-ore-magmatic cluster (North Vietnam)

New data on the gold mineralization related of the Late Paleozoic alkaline complexes of North Vietnam are presented. Two types of gold mineralization associated with syenites and granosyenites have been identified: gold only and gold-polymetallic. Geochemical characteristics are given for both types and the first data on the sulfur isotopic composition of ore minerals.

Fluid Inclusion Study of Epithermal Quartz Veins from the Kyaukmyet Prospect, Monywa Copper-Gold Ore Field, Central Myanmar

The Kyaukmyet prospect is located near the main ore bodies of the Kyisintaung and Sabetaung high-sulfidation Cu-Au deposits, Monywa copper-gold ore field, central Myanmar. Lithologic units in the research area are of mainly rhyolite lava, lapilli tuff and silicified sandstone, mudstone and siltstone units of Magyigon Formation which hosted to be polymetallic mineralization. Our field study recorded that epithermal quartz veins are hosted largely in rhyolite lava and lapilli tuff units. Those quartz veins show crustiform, banded (colloform), lattice bladed texture and comb quartz. The main objectives of the present research in which fluid inclusion studies were considered to conduct the nature, characteristics and hydrothermal fluids evolution from the epithermal quartz veins. In this research, there are three main types of fluid inclusions are classified according to their phase relationship (1) two-phase liquid-rich inclusions, (2) the coexisting liquid-rich and vapor-rich inclusions, and (3) only vapor-rich inclusions. Microthermometric measurements of fluid inclusions yielded homogenization temperatures (Th) of 148–282 °C and final ice-melting temperature (Tm) of -0.2°C to -1.4°C . The value of (Tm) are equal to the salinities reaching up 0.35 to 2.07 wt % NaCl equiv. respectively. Estimation formation temperature of the quartz veins provide 190°C and 210°C and paleo-depth of formation are estimated to be between 130m and 210m. Petrography of fluid inclusion and microthermometric data suggest that fluid boiling as well as mixing processes were likely to be happened during the hydrothermal fluid evolution at the Kyaukmyet prospect. According to the characteristics of many parameters including petrography of fluid inclusion, microthermometric data, paleo-depth, evidence of quartz vein textures and types of hydrothermal alteration from the Kyaukmyet prospect allows to interpret these data to be the low-sulfidation epithermal system.

THE MECHANISMS OF THE DISTRIBUTION OF HYDROTHERMAL-METASOMATIC GOLD- BEARING FORMATIONS (EAST OF THE SIBERIAN PLATFORM)

Hydrothermal-metasomatic formations with Au content from 0.5 to 3.0 g/t, sometimes up to 24-32 g/t, were found in the east of the Siberian platform in the brecciated zones. They form, along ancient faults activated in the Mesozoic, extended narrow formations in terrigenous-carbonate and sandy layers of PZ-MZ age. The comparison of metasomatites with gold-ore metasomatites of the Kuranakh and Tabornoye deposits makes it possible for the first time to predict ore sources formed as a result of hydrothermal-metasomatic processes. Perhaps these sources represent a huge metallogenic potential.

Effects of Small-Scale Gold Mining (SGM) to Mercury and Nutrient Contents in Soil in Kokap Subdistrict, Kulonprogo, Yogyakarta

Gold processing in Dusun Sangon, Kalirejo Village, Kokap Sub district, Kulonprogo Regency, SpecialRegion of Yogyakarta Province uses amalgamation method. Mercury use in gold processing has apotential impact on environmental damage and health of organism. Therefore, management onmercury-contaminated soil is needed to reduce environmental impacts. However, beforeperforming soil management, it is important to conduct research on initial condition of researchlocation, including research on the soil’s nutrient quality and mercury content. Testing wasconducted in the laboratory. Mercury (Hg) content testing used mercury analyzer testing method.pH testing used ISRIC 6th 2002 method. Organic carbon testing used SNI 13-4720-1998 testingmethod. Total nitrogen testing used SNI 2803-2010 testing method. C/N Ratio testing used SNI 13-4720-1998; SNI 2803-2010 testing methods. Results show that mercury contents in residualsamples of gold ore and soil samples were 4.81 mg/kg and 88.63 mg/kg respectively, which wereincluded in TC-B and TC-A in the aforementioned order. Meanwhile, mercury content in gold oreSamples 1 and 2 were 0.28 ppm and 0.14181 ppm respectively. Soil nutrient content parameters ofOrganic C, Total N, and C/N ratio were found to be very low. These results might be influenced byprocessing activities in gold ore mining.

The Separation of Carbonaceous Matter from Refractory Gold Ore Using Multi-Stage Flotation: A Case Study

As a pre-treatment method of refractory gold ore, carbonaceous matter (C-matter) flotation was investigated with multi-stage flotation by rougher, scavenger, and cleaner stages. Different dosages of kerosene and MIBC (4-Methyl-2-pentanol) were applied and the optimum dosage was selected by testing in each flotation stage. With the combination of each stage, four circuit designs were suggested, which were a single-stage rougher flotation (R), rougher-scavenger flotation (R+S), rougher-scavenger-scavenger cleaner flotation (R+S+SC), and rougher-rougher cleaner-scavenger-scavenger cleaner flotations (R+S+RC+SC). The results indicated that the scavenger flotation increased C-matter recovery but reduced C-matter grade compared with single-stage rougher flotation. Cleaning of the scavenger flotation concentrate improved C-matter grade significantly, but reduced recovery slightly. Cleaning of the rougher flotation concentrate achieved overall improved selectivity in flotation. A combination of rougher-scavenger flotation followed by cleaning of both concentrates (R+S+RC+SC) resulted in 73% C-matter recovery and a combined cleaner concentrate grade of 4%; the final tailings C-matter grade was 0.9%, where the C-matter remaining in the tailings was locked, and fine grained. The results demonstrate the need for the multi-stage flotation of C-matter from refractory gold ore to achieve selective separation and suggested the potential of C-matter flotation as the pre-treatment for efficient gold production.

Stratigraphic-lithological factors of the location of gold mineralization in the central part of the Bukantau Mountains in Uzbekistan

The leading role in the placement of gold mineralization in the Bukantau mountains belongs to structural and lithological factors. For gold-ore and gold-silver occurrences, sandy-shale strata of the flyschoid and olistostrome formations are favorable, then, rocks of the volcanogenic-dolomite-siliceous formation and then the carbonate formation (Okzhetpes type). The leading types of near-ore hydrothermal alteration of the host rocks in the studied deposits are silicification and, to a lesser extent, carbonatization and sericitization. They are accompanied by chloritization, biotitization, argillization, etc. Gold ore deposits and ore occurrences of sulfide-disseminated ores are confined mainly to the deposits of the Karashakh suite of the Middle Carboniferous (C2b + m1 kr). Moreover, gold-sulfide mineralization in the rocks of the Karashakh Formation is unevenly distributed.