How and Where Do Minerals Form?

Did you know that there are more than 5,000 different kinds of minerals on Earth?

Long, green crystal
vivid green, lumpy mineral
Yellow orange cube mineral in white chunky mineral
blue green smooth faceted mineral
Dark orange nubby mineral


Some form deep underground, while some form on the surface. Some form in just seconds, while others take thousands or millions of years to form. One thing all minerals have in common is that they come from nature. Minerals can form anywhere. 

Explore these five types of environments: Igneous, pegmatitic, metamorphic, hydrothermal, and weathering. How do they produce Earth's amazing variety of minerals?

Igneous Environments

Igneous rocks, and the minerals they contain, form when magma cools and hardens. They can form on or near Earth's surface, or deeper in Earth's crust.

Pegmatitic Environments

Pegmatites are a special kind of igneous rock characterized by large— occasionally enormous—interlocking crystals. They form where abundant water and certain chemical elements are present in a crystal.


Metamorphic rocks had previous “lives.” The minerals in the original rock formed under one set of conditions. Then, after being subjected to different degrees of heat, pressure, and abundance of water, they transformed into different minerals.

Hydrothermal Environments

Hydrothermal minerals form when water, heated by magma, circulates through cracks in rock. The water transports dissolved minerals, which crystallize into minerals in the cracks and small cavities as the water cools.

Weathering Environments

Rocks are changed when they are exposed to air, water, and ice at Earth's surface. Weathering is often accompanied by erosion—the transportation of weathered materials by flowing water, wind, ice, and gravity. 

Image Credits:

elbaite var watermelon, malachite with azurite, fluorite-calcite, fluorite, grossular w calcite and diopside (no credit), microcline with smoky quartz and topaz, microcline var. amazonite, elbaite (red), staurolite in muschovite schist, siderite with quartz, andradite with galena, diopside, dioptase, Denis Finnin/© AMNH; augite, orthoclase, quartz, chalcopyrite, sodalite, muscovite with microcline quartz, elbaite (green), fluorapatite with zinnwaldite, calcite with quartz var. amethyst, fluorite, epidote, fluorapophyllite, malachite, adamite, wulfenite, limonite, halite, Matt Shanley/© AMNH