A precious metal is a rare, naturally occurring metallic chemical element of high economic value. Chemically, the precious metals tend to be less reactive than most elements. They are usually ductile and have a high lustre. Historically, precious metals were important as currency but are now regarded mainly as investment and industrial commodities.
Silver is a soft, white, lustrous transition metal, it possesses the highest electrical conductivity of any element, the highest thermal conductivity of any metal and is the most reflective metal on the planet. The metal occurs naturally in its pure, free form (native silver), as an alloy with gold and other metals, and in minerals such as argentite and chlorargyrite. Most silver is produced as a byproduct of copper, gold, lead, and zinc refining.
Gold is a bright yellow dense, soft, malleable and ductile metal. The properties remain when exposed to air or water. It is one of the least reactive chemical elements, and is solid under standard conditions. The metal occurs often in free elemental (native) form, as nuggets or grains, in rocks, in veins and in alluvial deposits. It occurs in a solid solution series with the native element silver (as electrum) and also naturally alloyed with copper and palladium.
Platinum group metals are genetically associated with mafic and ultramafic rocks. In Zimbabwe the main platinum reserve is found in the Great Dyke. It in exceptional characteristic of platinum is its catalytic activities, chemical inertness over a wide temperature range and high melting point. It is used as a catalyst to reduce the emission of carbon monoxide and hydrocarbons from light duty vehicle, catalyst in the manufacture of nitric acid.
Palladium is a member of the platinum group metals.