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Sican tumi, or ceremonial knife, Peru, 850–1500 CE. Metallurgy in pre-Columbian America is the extraction, purification and alloying of metals and metal crafting by Indigenous peoples of the Americas prior to European contact in the late 15th century. Indigenous Americans had been using native metals from ancient times, with recent finds of ...
An orogenic gold deposit is a type of hydrothermal mineral deposit. More than 75% of the gold recovered by humans through history belongs to the class of orogenic gold deposits. [ 1] Rock structure is the primary control of orogenic gold mineralization at all scales, as it controls both the transport and deposition processes of the mineralized ...
Classification. Iron oxide copper gold (IOCG) deposits are considered to be metasomatic expressions of large crustal-scale alteration events driven by intrusive activity. The deposit type was first recognised by discovery and study of the supergiant Olympic Dam copper-gold-uranium deposit ( Olympic Dam mine ), and South American examples.
Hydrothermal mineral deposits are accumulations of valuable minerals which formed from hot waters circulating in Earth's crust through fractures. They eventually produce metallic -rich fluids concentrated in a selected volume of rock, which become supersaturated and then precipitate ore minerals. In some occurrences, minerals can be extracted ...
These metal sulfides, such as ferrous sulfide FeS, are often black or brown, leading to the dark color of sludge. Several groups of bacteria can use hydrogen sulfide as fuel, oxidizing it to elemental sulfur or to sulfate by using dissolved oxygen, metal oxides (e.g., iron oxyhydroxides and manganese oxides), or nitrate as electron acceptors. [105]
Fouling is the accumulation of unwanted material on solid surfaces. The fouling materials can consist of either living organisms ( biofouling, organic) or a non-living substance (inorganic). Fouling is usually distinguished from other surface-growth phenomena in that it occurs on a surface of a component, system, or plant performing a defined ...
Ore genesis. High-grade gold ore from the Harvard Mine, Jamestown, California, a wide quartz -gold vein in California's Mother Lode. Specimen is 3.2 cm (1.3 in) wide. Various theories of ore genesis explain how the various types of mineral deposits form within Earth's crust. Ore-genesis theories vary depending on the mineral or commodity ...
History of fluid mechanics. The history of fluid mechanics is a fundamental strand of the history of physics and engineering. The study of the movement of fluids (liquids and gases) and the forces that act upon them dates back to pre-history. The field has undergone a continuous evolution, driven by human dependence on water, meteorological ...