The
word “electrum” has invaded modern language. We see it pop up in
such diverse places as the Star Wars universe, numerous fantasy
games, and occasionally in a scientific context. Given the awareness
of the word it might be surprising that there is just a vague
understanding of what the material behind the word actually is. Is it
a new metal all its own? No, not actually. The earliest refined
examples of the material come from preserved ancient
coins from Miletus dated between 610 and 560 BC. The material
itself came from the Pactolus River which was controlled by the
kingdom of Lydia. The people of Lydia are thought to have been early
to capitalize on the profits
of being merchants and moving from agriculture to urban culture and
from barter to coin economy.
Electrum
is an alloy. It naturally occurs in the riverbed of the Pactolus
River (which natively carries between 70 and 90 percent gold) and
other areas of the world. Modern sources include the tertiary andesitic gold fields in the Americas, Hungary, and New Zealand. The coins of the region have been
tested to be an average of 53 percent gold, so the state was adding
silver and copper to the official alloy. There are some variations
among different professions as to what electrum is in a modern sense.
It has been called “white gold” by some or “nickel silver” by
others. Modern standards consider alloys of the material to be
electrum if they possess 20% or more silver
along with gold, copper, platinum, nickel, or zinc depending on the
source referred to. Since the Greek root word also applies to Amber,
many times ancient Electrum was more brassy colored than gold largely
in part to the addition of copper for coloration, durability, and
wear. In appearance the material maintains a metallic luster, and
has the malleability of gold.
Before
it was used for coins it also found use as a decorative
element. Ancient Egyptians used it to plate their pyramidions or
capstone of their pyramids and obelisks. It found use in jewelry and
as part of writing instruments and eating
utensils that were subjected to high wear. The gold blended with
silver prevented tarnishing making white-gold versions of electrum
highly sought after for both religious icons and personal adornment.
Gold and silver alone were considered too soft to be used pure.
Copper and lead were both easily incorporated into metal alloys with
gold and silver. While it does occur naturally, both in Turkey and in
the Americas, ancient people found it easy enough to make the alloy
artificially. One should note that modern white-gold
is palladium, nickel, and silver making it and modern electrum very
different creations.
When
looking at modern electrum most people see a gold-bearing
ore with at least 20% silver by weight. The pale golden color can
sometimes have a greenish tinge if copper is present. The streak made
by an electrum nugget will match the color of the metal. Both
hardness and density varies based on the silver content. Similar to
lead, nuggets of the material can be cut with a knife and they are
easily formed into other shapes. While electrum can be enjoyed on its
own and comes from many places that have a high silver concentration
often times it is used as a gold ore and processed to separate the
metals contained in it. At least one expert estimates that a good
percentage of “native gold” found as free nuggets from epithermal deposits is actually electrum.
