Precious Metal Determinants
Rarity And High Economic Value
A metal is considered "precious" if it is rare and is of high economic value. Under these twofactors, nine metallic chemical elements qualify as precious metals. These are, in noparticular order: gold, palladium, silver, rhodium, iridium, ruthenium, platinum, osmium, andrhenium.
Safety Issues Concerning Precious Metals
The metallic chemical elements collectively known as precious metals are called as suchbecause of their extreme rarity and high economic value. Precious metals occur naturally orare by-products of the processing of other less rare metals.In order of increasing mass abundance (parts per billion), the precious metals are rhenium,rhodium, iridium, ruthenium, osmium, gold, platinum, palladium, and silver. These metals arenot radioactive and are mostly used for industrial purposes and for jewelry.Still, precious metals have some safety issues attached to them:
Rhenium:
Since rhenium is used in very small amounts, its toxicity is virtually unknown. The hazardousproperty of rhenium halide, for example, may be attributed either to rhenium itself or to theother elements that make up the compound. Another rhenium compound - potassiumperrhenate - is known to have a median lethal dose much like that of sodium chloride(commonly known as table salt).
Rhodium:
Although rhodium is inert (being a noble metal, as almost all the other precious metals are), itcan be reactive, especially if used as compounds. In its basic form, however, rhodium is notknown to cause any harm.
Iridium:
Iridium, when finely divided, can pose some hazards - it can ignite in air. Apart from this,accidental exposure to a radioisotope of iridium may cause poisoning by radiation, burns, andeven death.
Ruthenium:
Three conditions may be associated with exposure to ruthenium: it can stain the skin; it may
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