Excerpt from Stuff Matters By Mark Miodownik
At some point humans made the discovery that would end the Stone Age and open the door to a seemingly unlimited supply
of the stuff. They discovered that a certain greenish rock, when put into a very hot fire and surrounded by red-hot embers,
turns into a shiny piece of metal. This greenish rock was malachite, and the metal was, of course, copper. It must have been
the most dazzling revelation. Suddenly the discoverers were surrounded not by dead inert rock but by mysterious stuff that
had an inner life. They would have been capable of performing this transformation with only a few particular types of rock,
such as malachite, because getting it to work reliably depends not just on identifying these rocks but also on carefully
controlling the chemical conditions of the fire. But they must have suspected that those rocks that didn't work, that remained
obstinately rock-like however hot the fire became, had hidden secrets. They were right. It's a process that works for many
minerals, although it would be thousands of years before an understanding of the chemistry required (controlling the
chemical reactions between the rock and the gases created in the fire) led to the next real breakthrough in smelting. In the
meantime, from around 5000 BC, early metal smiths used trial and error to hone the process of the production of copper. The
making of copper tools initiated a spectacular growth in human technology, being instrumental in the birth of other
technologies, cities, and the first great civilizations. The pyramids of Egypt are an example of what became possible once
there were plentiful copper tools. Each block of stone in each pyramid was extracted from amine and individually hand-
carved using copper chisels. It is estimated that ten thousand tons of copper ore were mined throughout ancient Egypt to
create the three hundred thousand chisels needed. It was an enormous achievement, without which the pyramids could not
have been built, however many slaves were used, since it is not practical to carve rock without metal tools. It is all the more
impressive given that copper is not the ideal material for cutting rock since it is not very hard. Sculpting a piece of limestone
with a copper chisel quickly blunts the chisel. It is estimated that the copper chisels would have needed to be sharpened
every few hammer blows in order for them to be useful. Which sentence shows that the human civilization has been positively affected by the discovery of copper A) in the meantime from around 5000 BC early metalsmith‘s use trial and error to hone in the process of the production of copper b)it is estimated that 10,000 tons of copper or for mine throughout ancient Egypt to create the 3000 chisels needed c) the making of cover tools initiated a spectacular grown and human technology being instrumental in the birth of technologies cities in the first great civilizations d)it is estimated that the copper chisels would have needed to be sharpened every few hammer blows in order to them to be useful