A metallurgical assay is a compositional analysis of an ore, metal, or alloy, usually performed in order to test for purity or quality.
A 19th-century assay laboratory in Tombstone Courthouse State Historic Park, Arizona.
A model of a late 19th-century Canadian (Yukon) seal used to certify the quality of assayed gold.
Colorado assay office – circa 1870 A.D.
1916 photograph of an assayer performing an electrolysis test on a gold sample at the United States Assay Office in New York.
Precious metals are rare, naturally occurring metallic chemical elements of high economic value. Precious metals, particularly the noble metals, are more corrosion resistant and less chemically 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 raw materials. Gold, silver, platinum, and palladium each have an ISO 4217 currency code.
Gold nugget
1,000 oz silver bar
500 g silver bullion bar produced by Johnson Matthey
1 oz Vienna Philharmonic gold coin