When magma is emplaced at depth or extruded onto the surface (then called lava), it starts to cool and mineral crystals can form.
When rocks get very hot, deep underground, they melt and become magma which is full of tiny parts called ions. As the magma cools down, those parts slow down and stick together to form crystals. And that's how new minerals are born.
Precipitation is the reverse process, in which ions in solution come together to form solid minerals.
Minerals like salt or calcite can form when water dries up or conditions change. And the dissolved stuff in the water turns back into solids.
The travertine terraces at Mammoth Hot Springs in Yellowstone Park are another example formed by calcite precipitation at the edges of the shallow spring-fed ponds.
Yellowstone's terraces and Great Salt Lake show how mineral deposits from naturally when water evaporates.
Some natural substances technically should not be considered minerals, but are included by excep
Such as water, mercury, and calcite.