Quality
Palladium is considered as a native metal even though
it is never 100% pure palladium. It normally occurs alloyed with platinum
ores and other elements of the platinum group in placer deposits.
Palladium, like all the platinum metals, occurs in volcanic rocks,
such as peridotite or norite. It is also found associated with nickel-copper
deposits. Palladium abundance in the Earth's crust is about 0.015
parts per million.
In industry palladium is often used with the addition
of other metals, including other PGMs.
The quality marks for palladium may be used on articles
composed of at least 95 per cent palladium or 90 per cent palladium
and 5 per cent platinum, iridium, ruthenium, rhodium, osmium or gold.
However, standard palladium purity is 99.95%.
Palladium forms useful alloys with many metals. When
added to small amounts of gold, the yellow color fades and alloys
containing 15 per cent palladium are quite white. Gold-palladium alloys,
with or without other elements, are used in jewelry as "white
gold". An alloy which contains 95 parts of palladium, 2 to 4
part of ruthenium and the remainder of rhodium, looks like platinum
but is only half as heavy.