Chemical Properties of Precious Metals

The table below lists some key chemical properties of the four precious metals. The information has been sourced from the website Environmental Chemistry and further chemical information on each metal can be found by clicking the link in the first row of the table.

The symbols Au, Ag, Pt and Pd are commonly used in the industry as shorthand references and form the basis of the currency codes for the precious metals.

A review of the table shows that gold and silver are very similar to each other. Platinum and palladium are likewise similar. Generally, compared to platinum and palladium, gold and silver have a lower melting and boiling point, are better conductors, softer, more reflective, and more abundant.

Property Gold Silver Platinum Palladium
Latin Name Aurum Argentum Platinum Palladium
Symbol Au Ag Pt Pd
Atomic Number 79 47 78 46
Atomic Mass 196.9665 107.8682 195.08 106.42
Melting Point (°C) 1064.58 961 1772 1552
Boiling Point (°C) 2807 2163 3827 2964
Density (gram per cubic centimeter) 19.32 10.50 21.45 12.02
Melting Point (°F) 1948.24 1762 3222 2826
Boiling Point (°F) 5058 3925 6921 5367
Density (punds per cubic inch) 0.697 0.379 0.883 0.434
Electrical Conductivity (106/cm Ω) 0.452 0.630 0.0966 0.095
Thermal Conductivity (W/cmK) 3.170 4.290 0.716 0.718
Hardness (vickers MNm-2) 216 251 549 461
Optical Reflectivity 95% 97% 73% 72%
Abundance in Earth's crust (parts per billion) 11 70 1 0.6
Abundance in seawater (parts per trillion) 10 2.4 0.27 0.068

The amount of gold extracted from the Earth's crust is around 5.5 billion ounces. Some esimate the amount of gold in the the Earth's oceans at around 25 billion ounces. However, there is no need to worry about the price of gold declining from a sudden surge in supply - at current prices it is not economic to extract gold from seawater. For example, below one part per million the Perth Mint struggles to recover gold economically from its waste water.