HISTORY - How we used Rocks & Minerals
We have made use of rocks and minerals from the very beginning of time. If you look at how we named the eras of human development, STONE AGE, COPPER AGE, BRONZE AGE and IRON AGE, it is obvious how important rocks and minerals have been to us all.
Very long ago, our ancestors used rocks for tools. This was known as the Stone Age. This period of human development lasted a long time - about 3 1/2 million years. This is also known as pre-historic times. This era ended about 4,000 to 6, 500 years ago when people learned how to make metal.
- Obsidian and flint were used for knives and spears
- River rocks were used to break other things
- Caves were used as places to live
- Rocks and boulders were used to sit on and to build fire pits
Depending on what part of the world people lived in, THE Stone Age was then followed by the Copper Age when people discovered how to smelt (melt using high heat) copper ore. In Britain, it was about 4,500 years ago and lasted for several centuries. This was not a long period because people quickly learned how to make other metals.
During this time, cities were being built and building stones were being used a lot.
The Copper Age was then followed by the Bronze Age about 6,000 years ago. Bronze is an alloy of copper. During this time, people learned how to mix minerals to produce metals like copper, bronze, lead and tin by smelting them.
Smelting ore is when you melt crushed rocks with minerals in them at very high temperatures. By adding other chemicals and minerals, the metals separate out and the metal can be poured off. Smelting is like melting with a purpose. The melted rock that is not metal is called slag.
The Bronze Age was then followed by the Iron Age which started about 3,000 years ago. During the Bronze Age they learned how to extract / make metal from rocks. During the Iron Age they learned how to make tools & implements (things they used) out of metal.
Iron is very strong and made very good and long lasting tools. Tools let people make things more easily.
These tools also meant that stone could be shaped more easily and many empires built buildings, structures and roads that still can be seen today. Since that time period, people have built many cities and used minerals extensively.
In MODERN TIMES, since about 1700 CE (or 400 years ago), we have been using rocks and minerals at an ever increasing rate as we build machines, cities and consume a great number of "things" in a lifetime. We use things made from rocks and minerals every day. If something doesn't come from a plant or an animal, it has to be mined.