Early History of Metal Use in Human Culture (L22) Flashcards
what were most metals used for?
ornamental purposes
What are the 4 stages of tool making by our ancestors?
- Oldowan tools - very simple, meant for cutting or chopping
- Acheulean tools - double edge, more refined appearance
- Mousterian tools - little more refined, maximized cutting surface
- Paleolithic tools - more sophisticated and use of a variety of materials
what were the preferred rocks for producing the tools made by our ancestors?
composed of silica, in the form of glass and quartz
what is the next widespread metal used by humans?
copper
What was an early metal that was discovered by stone age humans and what was it used for?
native gold - used for artistic objects of beauty as it was soft and mealleable
What were copper weapons used for?
for show of nobility than for use as tools
What were 3 major limitations of using copper as tools?
its brittleness and the softness of the metal (couldn’t hold a sharp edge for very long AND the availability of copper
what are 2 other metals that could have been used more or less?
silver, iron/nickel alloy
what was a major improvement to copper technology?
when it was discovered that copper could be annealed when heated
perimitted stronger tools to be made
how did copper become more available?
with the discovery that copper could be smelted from mineral compounds by heating
what are 2 reasons why smelting couldn’t have been a result of accidental “cooking” of metal ores in campfires?
the heat generated in a campfire is unlikely to have reached temperatures necessary to allow metals to seperate from the ore
the presence of large amounts of oxygen in a campfire would have readily oxidized any metal that was produced by melting
where is it likely that the first smelted ore was produced and why?
In a pottery kiln b/c high temp could be achieved in a kiln
how were metals smelted within a kiln?
the oxygen-starved conditions within a kiln would prevent the combination of pure metal with oxygen
also, the presence of fluxes would lower the melting point of minerals within the kiln and ultimately lowering the melting point of the metals
when do copper sulphides generally occur?
they occur with sulphides of other metals such as arsenic
what was the aresenic later replaced with and why?
Tin
tin lowers the melting point of copper making it easier for metal to be smelted
why is bronze moer useful for tools than copper?
it is harder than pure copper and the invention of brass casting made bronze more useful
What did smelted iron form rather than liquid droplets like other metals?
formed a spongy solid mass called “bloom”
how was purification of iron done?
accomplished by repeated heating and pounding of the bloom
what are 3 qualities of pure iron that are undesireable?
softer than bronze
too soft to hold a sharp edge
tends to oxidize (rust)
2 main advances in tech that iron has done?
steeling
tempering
what is tempering and what does it involve?
an effective method of altering the properties of steel
involves: the quenching (sudden cooling) of hot metal in water (to increase hardness) and reheating (to reduce brittleness)
What is Pig Iron?
melted iron being poured into moulds
why is it called pig iron?
b/c the molten iron was directed down a central trough with smaller offshoots that led to moulds and this reminded someone of piglets suckling on their mother
what did reheating the cast iron (pig iron) do?
drove off the excess carbon, making the product more elastic and malleable for final use
