scholarly journals Prediction of hydrothermal copper, gold, silver and lead-zinc in northwestern Yunnan using weight of evidence model

2005 ◽  
Vol 8 (3) ◽  
pp. 230-234 ◽  
Author(s):  
Jacob Kporfor ◽  
Chen Jiagou
Keyword(s):  
Weight Of Evidence ◽  
Gold Silver ◽  
Copper Gold ◽  
Lead Zinc ◽  
Evidence Model ◽  
Northwestern Yunnan

Part I. Friction of metals - Influence of oxide films on metallic friction

1952 ◽  
Vol 212 (1111) ◽  
pp. 450-452 ◽  
Keyword(s):  
Surface Damage ◽  
Metallic Contact ◽  
Degree Of Protection ◽  
Number Of Factors ◽  
Gold Silver ◽  
Zinc Cadmium ◽  
Natural Oxide ◽  
Lead Zinc ◽  
Relative Hardness ◽  
Metallic Friction

The mechanism of metallic friction, in air, has been investigated for loads ranging from 0.003 to 10000 g. The metals studied include platinum, gold, silver, copper, tin, lead, zinc, cadmium, magnesium, aluminium and chromium. The earlier work of Whitehead has been extended and simultaneous measurements made of the frictional force and the electrical resistance between the sliding surfaces. The results show that with most metals the natural oxide layer is sufficient to prevent metallic contact at very small loads. The degree of protection depends on a number of factors, such as the surface roughness, the thickness of the oxide film and in particular on the relative hardness of the oxide and the metal substrate. When sliding occurs solely on the oxide layers the friction is not necessarily less than that observed when appreciable metallic contact occurs. The surface damage is, however, greatly diminished on account of the reduced metallic interaction.

scholarly journals Металлогения Конгинской зоны Омолонского террейна (Северо-Восток Азии)

2021 ◽  
pp. 3-16
Author(s):  
A. N. Glukhov ◽  
◽  
V. V. Priymenko ◽  
M. I. Fomina ◽  
V. V. Akinin ◽  
...  
Keyword(s):  
Porphyry Copper ◽  
Gold Silver ◽  
Copper Gold ◽  
Polymetallic Mineralization ◽  
Polymetallic Ore ◽  
Copper Ores

The article presents new data on geology, mineralogy, and geochemistry of porphyry-copper, gold-silver, and silver-polymetallic ore occurrences in the Kongin magmatic zone of the Omolon terrane and granitoids, associated with it. It has been demonstrated that petrology and the age of granitoids are similar to those in the OCVB Penzhina segment. Mineralization of the Kongin zone is very close to that of the OCVB, differing in relatively high Mo in porphyry-copper ores and prevalence of silver-polymetallic mineralization over gold-silver.

Mapping Susceptibility Landslide by Using the Weight-of-evidence Model: A Case Study in Merek Valley, Iran

2007 ◽  
Vol 7 (22) ◽  
pp. 3342-3355 ◽  
Author(s):  
M.H. Rezaei Mog ◽  
M. Khayyam ◽  
M. Ahmadi ◽  
M. Farajzadeh
Keyword(s):  
Weight Of Evidence ◽  
Evidence Model

Socioeconomic Development in Balochistan

2020 ◽  
pp. 26-43
Author(s):  
Naveeda Erum ◽  
Naima Saeed ◽  
Tansif Ur Rehman
Keyword(s):  
Socioeconomic Development ◽  
Work Force ◽  
Factors Affecting ◽  
Agrarian Society ◽  
The World ◽  
Copper Gold ◽  
The Status ◽  
Lead Zinc ◽  
The Government ◽  
Juniper Forests

Balochistan has witnessed rapid social change since the 1970s. These changes were augmented by the national and international political situation. The traditional, tribal, and largely pastoral nomadic society of Balochistan gradually transformed into a modernizing agrarian society. On 1st July 1970, when ‘One Unit' was dissolved, Balochistan gained the status of a province and the bureaucratic expansion required educated work force. Thus, the Government of Pakistan expanded educational facilities in Balochistan, but this expansion continued at a very slow pace. Unfortunately, Balochistan is still the most backward province in terms of socioeconomic development in Pakistan. Though, it is the largest province in Pakistan, almost 44% of Pakistan's total area. It also possesses one of the largest blocks of juniper forests in the world. Along with it, Balochistan is rich in biodiversity and possess natural resources in abundance, like copper, gold, lead, zinc, iron, coal, and marble. This article focuses on the various factors affecting the socioeconomic development in Balochistan.

scholarly journals Synthesis of Medium-Sized Heterocycles by Transition-Metal-Catalyzed Intramolecular Cyclization

Molecules ◽  
2020 ◽  
Vol 25 (14) ◽  
pp. 3147 ◽  
Author(s):  
Mickael Choury ◽  
Alexandra Basilio Lopes ◽  
Gaëlle Blond ◽  
Mihaela Gulea
Keyword(s):  
Transition Metal ◽  
Intramolecular Cyclization ◽  
Biologically Active ◽  
Conformational Constraints ◽  
Synthesis Strategy ◽  
Gold Silver ◽  
Copper Gold ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed ◽  
Active Natural

Medium-sized heterocycles (with 8 to 11 atoms) constitute important structural components of several biologically active natural compounds and represent promising scaffolds in medicinal chemistry. However, they are under-represented in the screening of chemical libraries as a consequence of being difficult to access. In particular, methods involving intramolecular bond formation are challenging due to unfavorable enthalpic and entropic factors, such as transannular interactions and conformational constraints. The present review focuses on the synthesis of medium-sized heterocycles by transition-metal-catalyzed intramolecular cyclization, which despite its drawbacks remains a straightforward and attractive synthesis strategy. The obtained heterocycles differ in their nature, number of heteroatoms, and ring size. The methods are classified according to the metal used (palladium, copper, gold, silver), then subdivided according to the type of bond formed, namely carbon–carbon or carbon–heteroatom.

Mineral deposits of Latin America and the Caribbean. Preface

2020 ◽  
Vol 72 (3) ◽  
pp. P250820
Author(s):  
Joaquín A. Proenza ◽  
Lisard Torró ◽  
Carl E. Nelson
Keyword(s):  
Latin America ◽  
Iron Oxide ◽  
Dominican Republic ◽  
Iron Ore ◽  
Mineral Exploration ◽  
Mineral Deposits ◽  
Special Issue ◽  
Gold Silver ◽  
Copper Gold ◽  
The Caribbean

The region that encompasses Latin America and the Caribbean is a preferential destination for mining and mineral exploration, according to the Mineral Commodity Summaries 2020 of the US Geological Survey (https://www.usgs.gov/centers/nmic/). The region contains important resources of copper, gold, silver, nickel, cobalt, iron, niobium, aluminum, zinc, lead, tin, lithium, chromium, and other metals. For example, Chile is the world’s largest copper producer and the second largest lithium producer. Brazil is the world’s leading niobium producer, the second largest producer of iron ore, and the third-ranked producer of tantalum. Cuba contains some of the largest reserves of nickel and cobalt in the world, associated with lateritic Ni-Co deposits. Mexico is traditionally the largest silver producer and contains the two largest mines in this commodity and, along with Peru, Chile, Bolivia and Argentina, accounts for more than half of the total amount of global silver production. The region also hosts several world-class gold mines (e.g., Pueblo Viejo in the Dominican Republic, Paracotu in Brazil, Veladero in Argentina, and Yanacocha in Peru). Also, Bolivia and Brazil are among the world’s leading producers of tin. The region hosts a variety of deposit types, among which the most outstanding are porphyry copper and epithermal precious metal, bauxite and lateritic nickel, lateritic iron ore from banded iron-formation, iron-oxide-copper-gold (IOCG), sulfide skarn, volcanogenic massive sulfide (VMS), Mississippi Valley type (MVT), primary and weathering-related Nb-bearing minerals associated with alkaline–carbonatite complexes, tin–antimony polymetallic veins, and ophiolitic chromite. This special issue on Mineral Deposits of Latin America and the Caribbean in the Boletín de la Sociedad Geológica Mexicana contains nineteen papers. Contributions describe mineral deposits from Mexico, Panama, Cuba, Dominican Republic, Colombia, Venezuela, Ecuador, Chile, and Argentina. This volume of papers covers four mineral systems (mafic-ultramafic orthomagmatic mineral systems, porphyry-skarn-epithermal mineral systems, iron oxide copper-gold mineral systems, and surficial mineral systems). This special issue also includes papers on industrial minerals, techniques for ore discovery (predictive modelling of mineral exploration using GIS), regional metallogeny and mining history.

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