Gold telluride

Gold telluride iodide, AuTczI, was the first example of a gold chalco-genide halide, and was found in 1969 (305). Systematic investigations confirmed the existence of at least six compounds four telluride halides and two selenide halides (see Table IV). No sulfide halides have been reported. 

Gold telluride Thermal treatment AuTe2 —> Au + 2 Te Cyanide leaching... 

Occurrence. It is found in close association with sulphur and selenium. Tellurium is often found as gold telluride (calaverite), occasionally observed as free element. 

The pure form of tellurium burns with a blue flame and forms tellurium dioxide (TeO ). It is brittle and is a poor conductor of electricity. It reacts with the halogens of group 17, but not with many metals. When it reacts with gold, it forms gold telluride. Tellurium is insoluble in water but readily reacts with nitric acid to produce tellurous acid. If inhaled, it produces a garlic-like odor on one s breath. 

Gold is relatively inert in comparison to the other two coinage metals of GroupIB copper and silver. It also is chemically more inert than most other metals in the Periodic Table. It does not combine with oxygen, sulfur or selenium even at elevated temperatures. However, it reacts with tellurium in molten state forming gold telluride. 

Krennente is another tellunde of gold and silver with a similar composition to sylvanite. but crystallizing in the orthorhombic system. Calaverite is a gold telluride with only a small silver content,... 

Gold is a heavy yellow-colored element (symbol Au atomic no. 79). Its symbol derives from the Latin word aurum. It is usually found as the metallic element but can occur as salts such gold telluride (sylvanite). 

In 1798 Martin Klaproth, who had earlier discovered and named uranium, isolated the same silvery white metal from the same problematical ore. Klaproth, however, recognized that he and Muller had isolated a new element for which he suggested the name tellurium, meaning earth. He properly acknowledged the prior work of the Baron, who is consequently listed as its discoverer. Later it was found that tellurium does occasionally exist as the free element but more often than not exists as the gold telluride. Oddly, workers who process this ore and the metal derived from it acquire a garUc-Hke odor to their breath, a condition referred to (rather honestly but certainly not flatteringly) as tellurium breath. 

Monolayers can be transferred onto many different substrates. Most LB depositions have been perfonned onto hydrophilic substrates, where monolayers are transferred when pulling tire substrate out from tire subphase. Transparent hydrophilic substrates such as glass [18,19] or quartz [20] allow spectra to be recorded in transmission mode. Examples of otlier hydrophilic substrates are aluminium [21, 22, 23 and 24], cliromium [9, 25] or tin [26], all in their oxidized state. The substrate most often used today is silicon wafer. Gold does not establish an oxide layer and is tlierefore used chiefly for reflection studies. Also used are silver [27], gallium arsenide [27, 28] or cadmium telluride wafer [28] following special treatment. 

Tellurium is occasionally found native, but is more often found as the telluride of gold (calaverite), and combined with other metals. It is recovered commercially from the anode muds that are produced during the electrolytic refining of blister copper. The U.S., Canada, Peru, and Japan are the largest Free World producers of the element. 

Sanskrit Jval Anglo-Saxon gold L. aurum, gold) Known and highly valued from earliest times, gold is found in nature as the free metal and in tellurides it is very widely distributed and is almost always associated with quartz or pyrite. 

Tellurides, on the other hand, are readily floatable in the presence of small quantities of collector, and it is believed that tellurides are naturally hydrophobic. Tellurides from Minnesota (USA) were floated using dithiophosphate collectors, with over 9% gold recovery. 

The flotation of elemental gold, electrum and tellurides is usually very efficient, except when these minerals are floated from base metal, massive sulphides. 

Gold mineralization occurs as telluride phases lining fractures within quartz and associated with pyrite where it occurs both rimming pyrite and as inclusions ... 

German mining inspector Franz Joseph von Reichenstein Brittle metalloid poor conductor of electricity combines with gold to form telluride combined with other metals, it makes them easier to machine. 

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