Why are minerals found in certain places on Earth? Different minerals tend to concentrate in certain places on Earth because of geological conditions and the chemical condition in each place. Also, minerals in some places are just easier to get to than others.
Minerals are naturally occurring elements or compounds. Some minerals are formed from a single element, such as gold, and some minerals are formed from a mix of elements, such as quartz, which is made of one atom of silicon and two atoms of oxygen.
Recently, China has become known for producing rare earth metals, which are found in abundance there. Australia is a producer or iron ore, gold, and lots of other minerals. Diamonds from Botswana and Angola are a large percentage of the world’s diamond market. So, why do these minerals gather in these areas? We have to look at a few things here. We need to look at how minerals form and how they get transported. We also need to look at how they come to the surface.
There are several different ways a mineral can form. The three main ways are from water, from magma, and through pressure. Minerals form from water when it evaporates. Water runs over surfaces, or through rocks, and it picks up elements as it goes. These elements are suspended in the water and carried along. When the water is heated and turns to steam, the water molecules spread out and they can’t carry the extra elements anymore. These elements get dropped and form minerals. The second way is from magma. When rock is heated enough, it becomes viscous and can flow. This magma contains a large number of elements that move. When the magma cools down, the elements crystalize and minerals are left. The third way is through immense heat or pressure. Pressure can crush together elements that wouldn’t normally join up and it can squash their structures into certain shapes. Diamonds are the best example of this. The pressure crushes carbon atoms together and gives them an incredibly strong structure. The pressure can also change one mineral into another. If there is enough pressure, limestone, for example, can be turned into marble.
So, why are elements found in certain places? The main reason is that all of these processes don’t happen in the same place. The Earth is not exactly the same all over. In fact, no planet is exactly the same all over. There are variations in the geology which cause different things to happen. On top of that, the surface of the Earth is constantly moving. Minerals that are formed in one place get carried to another place. The magma is moving with heat convection currents, carrying elements all over the planet. The tectonic plates are also appearing, growing, and then being pulled back into the Earth. Elements move.
One of the reasons why elements appear to be in certain places more than others is because they have been driven to the surface in those areas. If a tectonic plate is pushed upwards or pulled downwards, it can carry minerals close to the surface. A volcano forming can push them up to the surface as well. Sometimes, a place that used to be a sea might dry up, and the evaporating water will leave minerals on the surface. There are many ways that minerals can be carried to the surface, but this doesn’t happen everywhere. A lot of minerals will stay deep underground.
The diamonds in Botswana are a good example of this process happening. Diamonds need incredible pressure to form, which they find at about 200 km under the surface. The diamonds in Botswana are found in something called a kimberlite pipe. About 90 million years ago, magma from deep in the ground flowed upwards towards the surface. As it did, it passed through the area where the diamonds were formed and carried huge chunks of rock and diamond with it. The magma pushed all these diamonds up and out onto the surface, and some of them stayed in the kimberlite pipe. Diamond miners know that if they find diamonds on the surface, there are probably more trapped underground and if they can find the kimberlite pipe, they can find more diamonds. That is why diamonds mines are usually open pit mines. They are just digging down through the kimberlite pipe. And this is what I learned today.
Sources
https://australian.museum/learn/minerals/what-are-minerals/
https://en.wikipedia.org/wiki/Mineral
https://australian.museum/learn/minerals/what-are-minerals/how-do-minerals-form/
https://education.nationalgeographic.org/resource/mineral-deposits
https://www.amnh.org/exhibitions/permanent/gems-minerals/how-do-minerals-form
https://earthobservatory.nasa.gov/images/87062/botswanas-diamond-mines
Photo by Tom Fisk: https://www.pexels.com/photo/birds-eye-photography-of-mine-2101135/