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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 ...
Bluing, sometimes spelled as blueing, is a passivation process in which steel is partially protected against rust using a black oxide coating. It is named after the blue-black appearance of the resulting protective finish. Bluing involves an electrochemical conversion coating resulting from an oxidizing chemical reaction with iron on the ...
A sight or sighting device is any device used to assist in precise visual alignment (i.e. aiming) of weapons, surveying instruments, aircraft equipment, [ 1][ 2] optical illumination equipment or larger optical instruments with the intended target. Sights can be a simple set or system of physical markers that serve as visual references for ...
Perls Prussian blue. In histology, histopathology, and clinical pathology, Perls Prussian blue is a commonly used method to detect the presence of iron in tissue or cell samples. [ 1]: 235 [ 2][ 3][ 4] Perls Prussian Blue derives its name from the German pathologist Max Perls (1843–1881), who described the technique in 1867. [ 2]
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Direct reduction processes can be divided roughly into two categories: gas-based and coal-based. In both cases, the objective of the process is to remove the oxygen contained in various forms of iron ore (sized ore, concentrates, pellets, mill scale, furnace dust, etc.) in order to convert the ore to metallic iron, without melting it (below 1,200 °C (2,190 °F)).
The Pederson process is a process of refining aluminum that first separates iron by reducing it to metal, and reacting alumina with lime to produce calcium aluminate, which is then leached with sodium hydroxide. [1] It is more environmentally friendly than the more well-known Bayer process. [2] This is because instead of producing alumina slag ...
Bindi (decoration) Hindu woman in Kullu, Himachal Pradesh wearing a bindi. A bindi (from Sanskrit bindú meaning "point, drop, dot or small particle") [ 1][ 2] is a coloured dot or, in modern times, a sticker worn on the centre of the forehead, originally by Hindus, Jains and Buddhists from the Indian subcontinent .