What Are Precious Metals?

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