677



▶ metallurgy

introduction
Historians identify major periods in ancient history by the
primary materials people used to make tools. Th us, the
Stone Age, the longest period identifi ed this way, extended
back some two million years ago. It ended at various times
throughout the world, perhaps about 6000 b.c.e. in the Near
East and Asia, 4000 b.c.e. in Europe, and 2500 b.c.e. in the
Americas. What brought the Stone Age to an end was the
widespread adoption of metal rather than stone for making
tools and weapons. Th e fi rst “metal age” was the Copper Age,
when tools made of copper began to be used along with those
made of stone. While copper was malleable and easy to work
and copper tools did not easily break, its usefulness was lim-
ited because it was not very hard.
A major advance in human civilization was the develop-
ment of bronze, an alloy of copper and tin. Th e combination
produced a much harder metal, allowing people to forge tools
that were more durable and could do more work. So impor-
tant was this development that historians refer to the period
running from about the fourth or third millennium b.c.e. to
roughly 1200 b.c.e. as the Bronze Age. Th ese dates, though,
are very approximate and diff ered widely depending on the
region of the world. Bronze did not even reach the Americas,
for example, until roughly 900 b.c.e. For this reason, histo-
rians oft en specify a region of the world in referring to the
Bronze Age, such as the Nordic Bronze Age or the Central Eu-
ropean Bronze Age.

Th e Bronze Age came to an end with the emergence of

iron as the favored metal, primarily because iron ore was

more plentiful and iron was cheaper to mine and refi ne. Ac-

cordingly, historians refer to the Iron Age, which followed

on the heels of the Bronze Age cultures that preceded it and

lasted through the remainder of ancient times. A further re-

fi nement of iron was the development of steel, which hard-

ened iron and enabled metalsmiths to make highly durable

tools. It is believed that the ancient Africans were the fi rst

to form hard carbon steel in the world’s fi rst blast furnaces,

which could reach extremely high temperatures.

Th e discovery of these metals required ancient peoples to

develop the science of metallurgy, referring to technologies for

extracting metals from ores, purifying them, combining them

with other metals to form alloys, and fashioning them into

useful objects. To create metal objects, the ancients learned

many forms of casting, or the process of pouring molten metal

into molds, where it would cool and harden. Th e mold was re-

moved, oft en by breaking it, leaving behind the metal object.

Another way of working metal, especially soft metal, was

hammering it into shape; annealing was a process to reduce

of the brittleness of hammered metal by heating it. Soft met-

als such as gold and silver were easily worked into primarily

decorative objects such as jewelry; they could also be used to

decorate objects made of iron and other materials, enhancing

their value and aesthetic appeal. Some historians have theo-

rized that ancient cultures discovered primitive batteries that

used electric current to deposit thin layers of metals on the

surface of other metals in a process called electroplating.

M