Minerals are the building blocks of rocks, and like rocks they can be formed in a wide range of geologic settings. Minerals can be formed during igneous processes when magma cools. Minerals can also be formed in metamorphic environments, where pre-existing rocks are taken to high temperatures and pressures. Minerals are formed in sedimentary settings when they precipitate out from water, or when water evaporates leaving minerals behind (like salt deposits). Finally, minerals are even formed by living organisms. For instance, your tooth enamel is made from a type of mineral called apatite.

The diverse ways in which minerals form goes to show how complicated the Earth system is. Furthermore, minerals can be recycled into new rock types. For example, quartz is a mineral found in igneous rocks like granite. It can be weathered away from igneous rocks and carried by rivers into sedimentary basins. From there, a sedimentary rock can form from the quartz (and other minerals). In this way, minerals can be much older than the actual rock that they are found in.

Minerals can form many ways, but minerals often form from gases, liquids, and solids. For gases minerals can form from in a gas with vapor in it, which is the way snowflakes form. Yes, the ice that makes up snowflakes is a mineral!

A mineral like salt can form from the drying up of a liquid with other material dissolved in it, or it can form by that liquid crystallizing. An example of a liquid crystallizing might be when ice crystals form on a freezing lake. Crystallization is also the way that minerals can form in magma chambers bellow volcanoes.

A new mineral can form by transforming from another mineral. That might happen because the atoms in a mineral need to rearrange because of a change in temperature or pressure. An example of a mineral changing like this is when the mineral that is used in pencil lead, called graphite, changes to diamond at high pressures. There are a couple other ways for minerals to form, but these are the main ones.

If we could zoom in to view the atoms in a mineral we would see that minerals need to have a regular structure of their atoms, which then gets repeated. So liquid water is not a mineral because the atoms aren't regularly arranged, but ice is a mineral.

Minerals generally form in two main ways:
1. When magma (hot melted elements inside the earth's crust) or lava (hot melted elements on the earths surface, like a volcano eruption) cools down. If its magma, when it cools it will turn into minerals inside the earths crust, if its lava, when it cools down it will turn into minerals on the earths surface.

2. Crystallization of materials dissolved in water. When the minerals become too concentrated to be dissolved anymore, the elements inside them combine and crystalize to make crystals.

Minerals are formed in different ways. Did you know that lots of minerals are formed by the actions of living things? There are many, many more minerals on Earth now than there were before there was life on Earth.

There's a mineralogist [a person who studies minerals] named Bob Hazen who has a mineral named after him. It's called Hazenite. He says it's made from the poop of bacteria! You can read about it here:
Hazenite

Rocks are made of many minerals. Minerals are crystals with a specific composition. For example, the mineral calcite is a crystal of calcium carbonate. My favorite mineral is mica. The black specks in granite rock are black mica. I think life started between sheets of black mica. You can see that on my website:
Professor Helen Hansma and mica

I don't have any good links for how minerals are formed. The links talk about volcanic lava, but that's not how most minerals are formed. I'm giving you this link:
minerals evolultion