As a naturally occurring alloy containing primarily gold and silver, electrum is a precious mineral. This mineral also contains other metals like copper in traces. Today electrum is also being produced artificially. In ancient times, Greeks used to refer to electrum as ‘white gold’. Today, mineralogists consider it as ‘refined gold.’
The color of electrum varies from pale yellow to bright yellow and this actually depends on the amount of gold and silver present in the alloy. The gold content present in naturally occurring electrum varies immensely depending on the region where it is found. In the present day region of Asia Minor, the gold content found in naturally occurring electrum varies between 70 to 90%.
Historical reports suggest that electrum was used as early as 3 B.C. in the Old Kingdom of Egypt. The ancient Egyptians used it for coating the exterior pyramids. They also used electrum for making ancient drinking vessels and coins. Electrum is either pale yellow or yellowish-white in colour. The term “electrum” is the Latinized form of the Greek word “elektron.” Elektron implies a metallic substance that is primarily made of gold but it is alloyed with silver.
In ancient times, electrum was usually referred as white gold. However, electrum could be more precisely referred to as “pale gold.” In modern times, the term white gold is generally referred to as gold that is alloyed with either one or several other metals, including nickel, silver, platinum, and palladium. Electrum is odourless and it is not soluble in water. The density of electrum varies between 12.5 gm/cm3 to 15 gm/cm3.
Electrum was used extensively for coinage purposes from the third millennium B.C. In fact, it was more preferred than gold as refining techniques of gold were not known at that point of time. There are always variations in the gold and silver content as electrum is an alloy. So, it was quite difficult to determine the value of coins produced from electrum. This would adversely impact the foreign trading system of ancient times.
Pure silver coins were then introduced in the year 570 B.C. However, the new silver coins did not completely replace electrum. This is because electrum coins were much more valuable than pure silver coins as the latter contained significant amount of gold. However, electrum coins were completely stopped from circulation around 350 B.C.
While performing physical and chemical analysis of electrum in a testing laboratory, electrum would meet the standard tests used for metallic, native gold. However, the test also implicate that electrum contains significant amount of silver. One of the distinguishing factors of electrum is the pale golden color; this shade is significantly lighter than the typical shade of native gold. Electrum is a good conductor of electricity.
Electrum is found in many localities of Hungary. Here, the deposits of electrum are present in Eocene volcanic rocks. Electrum is also found in epithermal deposits of New Zealand. In general, the free gold that is discovered from most epithermal deposits is nothing but electrum. In other words, electrum is an important ore of gold. Today, electrum is usually obtained from the tertiary andesitic goldfields that are present in America, New Zealand, and Hungary. The rich silver ores of Mexico, Chile, Bolivia, and Peru also contain electrum in significant amounts.