Very interesting question!

Just to bring us all on the same page, let's start with some information.

Minerals are made up of elements. Elements are the simple substances that cannot be broken down into any other substance. Elements are written as a combination of letters called the element symbol, and minerals are written as a formula symbol. As an example, salt, something you might put on your food, is a mineral. The mineral name used is halite. Salt is made from the elements sodium (Na) and chlorine (Cl), and written by the formula NaCl. Many minerals are made up of a bunch of elements, so their formulas are quite complex.

Almost every human-made item you can point to, from calcium carbonate in toothpaste to graphite in your pencil, is created from some basic minerals. Currently the International Mineralogical Association recognizes over 5,300 known mineral species. That's a lot of minerals!

Ok, so what is a mineral? Scientists have been refining the definition of a mineral for the past several hundred years. The broad-standing agreement is that minerals are naturally-occurring inorganic substances (meaning neither made by living organisms nor have ever been alive) with a definite and predictable chemical composition (think of salt's formula: NaCl) and physical properties (the mineral's hardness, shape, color, etc.). They are always crystalline (meaning solid; minerals cannot be a liquid or gas), but the crystals may be so tiny that they are only visible using a microscope.

Minerals are the chemical building blocks that rocks are made from, so minerals are the basic materials that form Earth. They are also the building blocks of us! Our skeletons and teeth are made from minerals through complex processes inside our bodies. The abundance and diversity of minerals is controlled by their chemistry (again think of the sodium (Na) and chlorine (Cl) in salt) and how they form.

Minerals form in two ways:
1) Minerals form from cooling magma, and
2) minerals form from the evaporation of water.
Magma is melted, or liquid, rock that is underground. As the magma moves closer to Earth's surface, it begins to cool. As it cools, the atoms inside the magma move close together and solidify to form crystals. Many valuable minerals such as diamonds, rubies, and emeralds form this way. In the other method, minerals form when water evaporates out of a mixture of elements. The mineral is the remaining chemical substances that were once dissolved inside the water. This is how salt forms. Salt water contains sodium (Na) and chlorine (Cl). When salt water evaporates, it leaves behind the Na and Cl atoms. The Na and Cl atoms then combine to form the mineral halite, or salt.

Because of the ways that minerals form, they are either found in shapeless lumps, which we call "massive," or they form into special shapes we recognize as crystals. Most minerals form within the spaces between other minerals, growing into rough and shapeless masses. However, if the minerals can form freely in a hole or cavity, the mineral takes the form of a crystal. So, minerals can be found everywhere, since they make up rocks, and all of Earth's surface is covered in rocks (even the bottom of the ocean).

Concentrated mineral deposits, which is typically what you think of when "looking" for minerals, are located wherever the geologic process occurs that forms the deposit. Since every mineral may have a different process that concentrates it,there are minerals to be found all over the world on every continent. It depends on what minerals you are seeking before you can narrow down where those minerals might form.