Initial exploration results of the Collins epithermal Au‐base metal prospect, Aceh, Indonesia

2021 ◽  
Author(s):  
Thomas Mulja ◽  
Shane Ebert ◽  
Lee A. Groat
Keyword(s):  
Base Metal ◽  
Initial Exploration ◽  
Epithermal Au

scholarly journals Selenium-Rich Ag–Au Mineralization at the Kremnica Au–Ag Epithermal Deposit, Slovak Republic

Minerals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 572 ◽  
Author(s):  
Martin Števko ◽  
Jiří Sejkora ◽  
Zdeněk Dolníček ◽  
Pavel Škácha
Keyword(s):  
Base Metal ◽  
Slovak Republic ◽  
Epithermal Deposit ◽  
Ore Minerals ◽  
Ore Mineralization ◽  
Ore Mineralogy ◽  
Chemical Trends ◽  
New Phase ◽  
Epithermal Au ◽  
Ore District

Selenium-rich Au–Ag mineralization has been discovered in the Kremnica ore district, central Slovakia. The mineralization is hosted by a single quartz–dolomite vein hosted by Neogene propyllitized andesites of the Kremnica stratovolcano. Ore mineralogy and crystal chemistry of individual ore minerals have been studied here. The early base-metal ore mineralization composed of pyrite, sphalerite, and chalcopyrite lacks selenium, whereas the superimposed Au–Ag paragenesis is Se-enriched. The Au–Ag alloys, uytenbogaardtite, minerals of the galena–clausthalite series, acanthite–naumannite series, diaphorite, miargyrite, pyrargyrite–proustite, polybasite group, minerals of the tetrahedrite group and andorite branch (andorite IV, andorite VI, Ag-excess fizélyite), freieslebenite, and rare Pb–Sb sulphosalts (scaiinite, robinsonite, plagionite) have been identified here. Besides selenides, the most Se-enriched phases are miargyrite, proustite–pyrargyrite, and polybasite–pearceite, whose Se contents are among the highest reported worldwide. In addition, one new phase has been found, corresponding to a Se-analogue of pearceite containing 2.08–3.54 apfu Se. The style of mineralization, paragenetic situation, and chemical trends observed in individual minerals are comparable to those of Au–Ag low-sulphidation epithermal Au–Ag mineralizations of the Kremnica and neighboring Štiavnica and Hodruša-Hámre ore districts. However, the pronounced enrichment in selenium is a specific feature of the studied vein only.

Cenozoic Strike-Slip Tectonics and Structural Controls of Porphyry Cu-Mo and Epithermal Deposits During Geodynamic Evolution of the Southernmost Lesser Caucasus, Tethyan Metallogenic Belt

2019 ◽  
Vol 114 (7) ◽  
pp. 1301-1337 ◽  
Author(s):  
Samvel Hovakimyan ◽  
Robert Moritz ◽  
Rodrik Tayan ◽  
Rafael Melkonyan ◽  
Marianna Harutyunyan
Keyword(s):  
Base Metal ◽  
Strike Slip ◽  
Early Miocene ◽  
Tectonic Plate ◽  
Porphyry Cu ◽  
Metallogenic Belt ◽  
Late Neogene ◽  
Lesser Caucasus ◽  
Dextral Strike Slip ◽  
Epithermal Au

Abstract The Zangezur-Ordubad mining district of the southernmost Lesser Caucasus is located in the central segment of the Tethyan metallogenic belt and consists of porphyry Cu-Mo and epithermal Au and base metal systems hosted by the composite Cenozoic Meghri-Ordubad pluton. Ore-hosting structures and magmatic intrusions are predominantly confined to a central N-S–oriented corridor 40 km long and 10 to 12 km wide, located between two regional NNW-oriented right-lateral faults, the Khustup-Giratagh and Salvard-Ordubad faults. The anatomy and kinematics of the main fault network are consistent with dextral strike-slip tectonics controlled by the NNW-oriented Khustup-Giratagh and Salvard-Ordubad faults. Dextral strike-slip tectonics was initiated during the Eocene, concomitantly with final subduction of the Neotethys, and controlled the emplacement of the Agarak, Hanqasar, Aygedzor, and Dastakert porphyry Cu-Mo and Tey-Lichkvaz and Terterasar epithermal Au and base metal deposits. The Eocene structures were repeatedly reactivated during subsequent Neogene evolution in transition to a postsubduction geodynamic setting. Ore-bearing structures at the Oligocene world-class Kadjaran porphyry Cu-Mo deposit were also controlled by dextral strike-slip tectonics, as well as porphyry mineralization and its epithermal overprint hosted by an early Miocene intrusion at Lichk. Eocene to early Miocene dextral strike-slip tectonics took place during NE- to NNE-oriented compression related to Paleogene Eurasia-Arabia convergence and subsequent Neogene postcollision evolution. Paleostress reconstruction indicates major reorganization of tectonic plate kinematics since the early Miocene, resulting in N-S– to NW-oriented compression. Early Miocene epithermal overprint at the Kadjaran porphyry deposit and left-lateral reactivation of faults and mineralized structures are linked to this late Neogene tectonic plate reorganization.

scholarly journals Selenium-Rich Ag-Au Mineralization at the Kremnica Au-Ag Epithermal Deposit, Slovak Republic

2018 ◽  
Author(s):  
Martin Števko ◽  
Jiří Sejkora ◽  
Zdeněk Dolníček ◽  
Pavel Škácha
Keyword(s):  
Base Metal ◽  
Slovak Republic ◽  
Epithermal Deposit ◽  
Ore Minerals ◽  
Ore Mineralization ◽  
Ore Mineralogy ◽  
Chemical Trends ◽  
New Phase ◽  
Epithermal Au ◽  
Ore District

Selenium-rich Au-Ag mineralization has been discovered in the Kremnica ore district, central Slovakia. The mineralization is hosted by a single quartz-dolomite vein hosted by Neogene propyllitized andesites of the Kremnica stratovolcano. Ore mineralogy and crystal chemistry of individual ore minerals have been studied here. The early base-metal ore mineralization composed of pyrite, sphalerite and chalcopyrite lacks selenium, whereas the superimposed Au-Ag paragenesis is Se-enriched. The Au-Ag alloys, uytenbogaardtite, minerals of the galena-clausthalite series, acanthite-naumannite series, diaphorite, miargyrite, pyrargyrite-proustite, polybasite group, minerals of the tetrahedrite group and andorite branch (andorite IV, andorite VI, Ag-excess fizélyite), freislebenite, and rare Pb-Sb sulphosalts (scaiinite, robinsonite, plagionite) have been identified here. Besides selenides, the most Se-enriched phases are miargyrite, proustite-pyrargyrite, and polybasite-pearceite, whose Se contents are among the highest reported worldwide. In addition, one new phase has been found, corresponding to a Se-analogue of pearceite containing 2.08 - 3.54 apfu Se. The style of mineralization, paragenetic situation, and chemical trends observed in individual minerals are comparable to those of Au-Ag low-sulphidation epithermal Au-Ag mineralizations of the Kremnica and neighboring Štiavnica and Hodruša-Hámre Ore Districts, however, the pronounced enrichment in selenium is a specific feature of the studied vein only.

Revisiting the passivation of stainless steels and other passive CRAs

2018 ◽  
Vol 106 (1) ◽  
pp. 107 ◽  
Author(s):  
Jean- Louis Crolet
Keyword(s):  
Electrical Conductivity ◽  
Metal Ions ◽  
Base Metal ◽  
Stainless Steels ◽  
Electronic Conductivity ◽  
Transport Processes ◽  
General Knowledge ◽  
Inorganic Polymers ◽  
Faraday Cage

All that was said so far about passivity and passivation was indeed based on electrochemical prejudgments, and all based on unverified postulates. However, due the authors’ fame and for lack of anything better, the great many contradictions were carefully ignored. However, when resuming from raw experimental facts and the present general knowledge, it now appears that passivation always begins by the precipitation of a metallic hydroxide gel. Therefore, all the protectiveness mechanisms already known for porous corrosion layers apply, so that this outstanding protectiveness is indeed governed by the chemistry of transport processes throughout the entrapped water. For Al type passivation, the base metal ions only have deep and complete electronic shells, which precludes any electronic conductivity. Then protectiveness can only arise from gel thickening and densification. For Fe type passivation, an incomplete shell of superficial 3d electrons allows an early metallic or semimetallic conductivity in the gel skeleton, at the onset of the very first perfectly ordered inorganic polymers (- MII-O-MIII-O-)n. Then all depends on the acquisition, maintenance or loss of a sufficient electrical conductivity in this Faraday cage. But for both types of passive layers, all the known features can be explained by the chemistry of transport processes, with neither exception nor contradiction.

Aplikasi metode tahanan jenis dalam studi geologi karst Gua Seropan di Gunung Kidul, Yogyakarta

2017 ◽  
Vol 12 (2) ◽  
pp. 105-116
Author(s):  
Pulung A. Pranantya ◽  
Nurlia Sadikin
Keyword(s):  
Fresh Water ◽  
Ground Surface ◽  
Water Source ◽  
Raw Water ◽  
Limited Information ◽  
Resistivity Method ◽  
Central Java ◽  
Underground River ◽  
Initial Exploration

In terms of geology, most areas in south of the Gunungkidul District in Central Java consist of the Wonosari formation limestone. The land is generally very dry and source of raw water is also difficult to reach. Findings on the existence of underground river in caves, however, indicate the potential amount of water within the area, especially in the eastern part of the Gunungkidul District. Although limited information available, some fishermen have discovered that Seropan cave contains fresh water source. This cave is situated at 65 m below the cliff. Initial exploration, which done using a multichannel resistivity method, confirmed the availability of freshwater in the cave and underground river. The isopach of cave depth is found in ranges of 80 200 m below the ground surface. The water of Seropan cave can be utilized by implementing pipeline or by drilling at the suggested point based on the interpretation results, i.e. 110o2223.6388 EL 8o42.874 SL. [DY1][PP2][DY1]Perbaiki grammarIn terms of geology, most areas in south of Gunungkidul District in Central Java consist of the Wonosari formation limestone. The land is generally very dry and source of raw water is also difficult to reach. Findings on the exixtence of underground river in caves, however, indicate potential amount of water within the area especially in eastern part of Gunungkidul District. Although limited information available, some fishermans has discovered that Seropan cave contain fresh water source. This cave is situated at 65 m below the cliff. Initial exploration, which done using multichannel resistivity method, confirmed the availability of freshwater in the cave and underground river. The iso pach of cave depth is found in ranges of 80 200 m below the ground surface. The water of Seropan cave can be utilized by implementing pipeline or by drilling at the suggested point based on the interpretation results i.e. 110o2223.6388 EL 8o42.874 SL.[PP2]Sudah diperbaiki

Brahmi legends on Umayyad Fulus: Interrogating local minting practices and numismatic transculturation in Gandhara (ca. 750 CE)

Afghanistan ◽  
2019 ◽  
Vol 2 (1) ◽  
pp. 153-165
Author(s):  
Waleed Ziad
Keyword(s):  
Base Metal ◽  
Late Antiquity ◽  
Eighth Century ◽  
Political Authority ◽  
Unusual Feature ◽  
Complex Relationship ◽  
Contact Zones ◽  
Confessional Identity ◽  
Derivatives Of

This paper concerns a historically significant find of copper derivatives of Umayyad post-reform fulus from Gandhara, probably minted in the mid-eighth century under Turk Shahi sovereignty (c. 667–875). The coins share an unusual feature: two Brahmi aksharas on an Umayyad AE prototype, inversely oriented to a partially-corrupted Arabic legend. These base metal coins represent perhaps the only known caliphal imitative varieties issued by moneyers beyond the eastern limits of Umayyad and Abbasid sovereignty. They have the potential to inform our understanding of the complex relationship between political authority, confessional identity, and coin typology in late antiquity – particularly within early “Hindu”– “Muslim” contact zones. Moreover, they provide invaluable clues into the circulatory regimes of Umayyad coinage.

Peculiarities of electrode and base metal melting in electroslag welding

2019 ◽  
Vol 2019 (3) ◽  
pp. 12-17
Author(s):  
I.I. Lychko ◽  
◽  
K.A. Yushchenko ◽  
S.A. Suprun ◽  
S.M. Kozulin ◽  
...  
Keyword(s):  
Base Metal ◽  
Electroslag Welding ◽  
Metal Melting
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