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What are igneous rocks? Volcanic stone

By |2018-04-21T11:56:41-07:00June 26th, 2017|Geology|

Obsidian tools Igneous means "fiery", and igneous rocks are rocks that were made by heating them up in a fire. Usually that fire is the big fire inside the earth, under the earth's crust. Inside the earth, radioactivity creates very high temperatures of about 1000 degrees Celsius (that's about 1800 degrees Fahrenheit). Because [...]

Feldspar rock – a kind of igneous rock

By |2019-06-07T19:17:22-07:00June 25th, 2017|Geology|

A feldspar rock quarry in India Is feldspar rare? Feldspar is a very common igneous rock. More than half of the Earth's crust is made of feldspar. What are igneous rocks? All our geology articles What is feldspar made of? When molecules of aluminum, silica and oxygen get together with potassium, they combine [...]

Ancient Economy – Simple economic history

By |2018-04-19T11:10:59-07:00June 12th, 2017|Economy|

Ancient economy: a bone sickle - the flint teeth are missing now Trade or self-sufficiency? Even today experts don't really understand how economics works. Historians also disagree about how economics worked in antiquity and in the middle ages. Some historians think that long ago most people were self-sufficient. They ate and wore mostly [...]