The Building Blocks of Rocks

Mining and Exploration

Geology Handbook

Minerals – The Building Blocks of Our World

Minerals are the fundamental components of rocks, and understanding their properties and formation can help us appreciate the beauty and complexity of our planet. In this article, we will dive into the world of minerals, exploring their formation, classification, and the environments in which they can be found.

What Are Minerals and Why Are They Important?

Minerals are naturally occurring inorganic substances with a well-defined chemical composition and a specific crystalline structure. They are essential because they make up the building blocks of rocks, which in turn form the Earth’s crust. Studying minerals helps geologists understand the geological history and processes that shape the Earth over time.


The Formation of Minerals

Minerals can form in several ways, with the most common methods being crystallization from magma, precipitation from water, and metamorphism. Let’s take a closer look at these processes:

  1. Crystallization from magma: As magma cools, minerals start to crystallize and grow. This process is known as igneous crystallization, and it leads to the formation of igneous rocks like granite and basalt.

  2. Precipitation from water: Minerals can also form when dissolved substances in water reach saturation and begin to precipitate. This process typically occurs in sedimentary environments, leading to the formation of sedimentary rocks like limestone and gypsum.

  3. Metamorphism: When rocks are subjected to high temperatures, pressure, or chemically active fluids, they undergo changes in their mineral composition and structure. This process, called metamorphism, results in the formation of metamorphic rocks like marble and schist.

Classifying Minerals

Minerals are classified into several groups based on their chemical composition. The most common groups include:

  • Silicates: These minerals contain silicon and oxygen, making up about 90% of the Earth’s crust. Examples include quartz, feldspar, and mica.

  • Carbonates: Carbonate minerals are composed of carbonate ions (CO3) combined with metal ions like calcium, magnesium, or iron. Common examples are calcite and dolomite.

  • Oxides: Oxide minerals consist of metal ions bonded with oxygen. Examples include hematite (Fe2O3) and magnetite (Fe3O4).

  • Sulfides: Sulfide minerals are composed of metal ions bonded with sulfur. Examples are pyrite (FeS2) and galena (PbS).

  • Sulfates: Sulfate minerals contain the sulfate ion (SO4) combined with metal ions. Examples include gypsum (CaSO4·2H2O) and barite (BaSO4).

Where to Find Minerals

Minerals can be found in various environments across the Earth. Some common places to look for minerals include:

  • Igneous environments: Intrusive igneous rocks like granite and pegmatite are known for their mineral richness, hosting minerals like quartz, feldspar, and mica.
  • Sedimentary environments: Limestone and evaporite deposits can be rich in minerals such as calcite, gypsum, and halite.
  • Metamorphic environments: Minerals like garnet, kyanite, and staurolite can be found in metamorphic rocks formed under high temperature and pressure conditions.
  • Hydrothermal veins: Hot water circulating through the Earth’s crust can deposit minerals like gold, silver, and copper in veins and fractures.

Mining and Mineral Resources

Minerals are not only fascinating from a geological perspective, but they also hold significant economic value. Many minerals, such as gold, silver, and copper, are mined for their monetary worth, while others, like gypsum, limestone, and quartz, have various industrial applications.

Mining has been a vital part of human civilization for thousands of years, providing resources for tools, construction materials, and energy production. However, it’s essential to balance the benefits of mining with its environmental and social impacts. Responsible mining practices and reclamation efforts can help mitigate the potential negative consequences of extracting mineral resources.

Minerals in Everyday Life

It’s easy to overlook the importance of minerals in our daily lives, but they are present in numerous products we use every day. From the glass in our windows to the aluminium in our cars, the metals in our electronics, and the gypsum in our drywall, minerals play a crucial role in modern society.

As technology continues to advance, the demand for specific minerals, like rare earth elements and lithium, is on the rise. These minerals are essential components in the production of renewable energy technologies, such as solar panels and electric vehicle batteries.

Collecting Minerals as a Hobby

Mineral collecting is a popular hobby for those interested in geology and the beauty of natural formations. Collectors can search for minerals in the field, visit mineral shows, or purchase specimens from dealers. Collecting minerals can be a rewarding and educational experience, as it allows enthusiasts to connect with nature and learn about the geological processes that create these stunning formations.

To get started in mineral collecting, it’s essential to familiarize yourself with the basic tools and safety precautions required for field collecting. A good field guide, a rock hammer, and protective gear like goggles and gloves are indispensable for any aspiring mineral collector.

Mineral varieties can vary by small amounts of impurities. 

Amethyst is a purple variety of Quartz

Classification: Large Crystals or small crystals?


The individual crystal size of all rocks cooling from magma or lava is a direct result of how much time they have to grow. The longer a mineral has to grow, the larger the crystals will be. This means the speed at which molten rock solidifies directly determines the size of the crystals.

So for a given magma composition, there will be an extrusive and an intrusive version, Chemically identical to each other. Basalt is the extrusive (from lava flows) version of Gabbro. Rhyolite is the extrusive version of Granite.

And just to get confusing, some magmas may cool quickly at one point, but slowly at another (two stage cooling) which will result in some large crystals in a mostly small crystal rock. These rocks and their texture are classified as porphyritic.

A magma that has millions of years to cool deep in the earth will tend to form/grow large easily distinguishable crystals. A magma (or lava at the earth’s surface) which explodes into air or water and cools very quickly will only have very tiny crystals – so small you may need magnification to see them.

Fractional crystallization.

There are also rocks where some crystals form and sink to the bottom of the magma, then another, and another… forming layers. This is especially important to the formation of chromite deposits.


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