 Metals sporadically occur in nature in pure
enough concentrations that they were recognized
and exploited in prehistoric times. Softer metals
like gold and copper can be worked by hammering
without heating.

It is surmised that ceramic production created
the technological foundation for the smelting of
metal.
 Copper ores come in two basic forms: sulphides
and oxides. Sulphide ores contain a metal
combined with sulphur. Early miners were
attracted to oxides because they were easily
recognizable, accessible, and easier to prepare for
smelting. Sulphide ores have to be roasted before
they are smelted.
 Early miners were limited to metal deposits occurring
on the surface.
 Once extracted, it was necessary to pound the ore
to separate the metal ore from the gangue – the
worthless host rock.
 The melting point of copper is 1100˚ Celsius.
 The earliest smelting used charcoal and blow pipes.
 The copper would be melted in the furnace and
collected after cooling in the form of prills, or round
droplets.
 These would then be melted in a crucible.
 Molten copper would be poured into an open mold
of stone.
 The earliest copper artifacts in the Middle East
were trinkets such as bracelets and beads.
 In northern Europe tools such as axes and awls
were made. These quickly replaced their stone and
bone counterparts.
 As metal demand increased, and higher
grade ores became exhausted, smelters
turned to slagging processes to increase
production and efficiency.
 Fluxes like sand and manganese were added
to enhance the separation of the silica rich
slag from the metal.
 It was discovered that adding arsenic or tin
to copper produced a metal that was harder.
The resulting metal is bronze.
 Tin is a rarer metal than copper, and trade
routes came into being to transport tin over
long distances.
 More complex tools
and weapons were
made during the
Late Bronze Age,
enabled by clay
molds and the lost
wax technique.
Iron Age Vietnamese
bronze drum made by
the lost wax technique.
 X-ray florescence: An object is bombarded with x-
rays. This excites the atoms and causes them to
fluoresce (glow). Differing atoms are excited at
different energy levels.
 One determine which elements are present, and
determine the quantities.
 A technique that reveals the types and configurations
of minerals and that make up a sample.
 A slice is made of a rock that is so fine that light can
penetrate the grains.
 It is examined under a petrographic microscope under
polarizing light.
 Iron melts at 1550˚ celsius, therefore
smelting required a shaft furnace.
Iron Collects at the bottom of the furnace as a bloom
Containing many
impurities, the bloom
required working by a
smith.