What Are Precious Metals?
Precious metals are elemental metals that have high economic
value. Metals are classified as precious
because of their use in currency, investment, jewelry, industry and rarity.
Historically, precious metals were important as currency but
are now regarded as investment and industrial commodities. However, the most widely known precious
metals have ISO 4217 currency codes:
Gold: XAU
Silver: XAG
Platinum: XPT
Palladium: XPD.
Precious metals are chemically less reactive than most
elements, usually ductile, have a high lustre, and high electrical
conductivity. For example, Silver is the
most electrically conductive and the most thermally conductive metal.
Rarity is a chief characteristic of precious metals. Rarity
relates to the relative abundance of the element in the Earth’s crust and the
relative difficulty of extracting it from ores.
Aluminium was considered a precious metal until modern mining techniques
made it easy to obtain.
The fifteen precious metals listed in descending order by
atomic number are: Beryllium (4), Gallium (31), Germanium (32), Ruthenium (44),
Rhodium (45), Palladium (46), Silver (47), Tellurium (53), Rhenium (75), Osmium
(76), Iridium (77), Platinum (78), Gold (79), Mercury (80), and Bismuth (81). The Platinum Group
includes Ruthenium, Rhodium, Palladium, Osmium, Iridium, and Platinum. The precious metals are shown outlined in red in the Periodic Table.
This table shows the relative abundance of the precious
metals in Earth’s crust in Parts per Billion:
Rhenium
|
0.7
|
Rhodium
|
1
|
Iridium
|
1
|
Ruthenium
|
1
|
Tellurium
|
1
|
Osmium
|
1.5
|
Gold
|
4
|
Platinum
|
5
|
Bismuth
|
8.5
|
Palladium
|
15
|
Indium
|
50
|
Silver
|
75
|
Mercury
|
85
|
Germanium
|
1500
|
Beryllium
|
2800
|
Gallium
|
19000
|
