If you are sitting at your desk, reading this on your phone or computer, look around you. What objects do you see? Beyond your electronic device, you may also have a pencil, your clothes, a wall or windows. Your electronic device is full of metal circuits, and your pencil contains the mineral graphite. Your clothes might contain polyester, a plastic fabric derived from oil. The walls may have plasterboard derived from the mineral gypsum, and the windows are constructed using sand and limestone. The common link between all of these items is the source of raw material used to create them: mineral resources.
- Here, we’ll learn all about mineral resources.
- First, we’ll see what mineral resources are.
- Then, we’ll describe the main types of mineral resources.
- We’ll continue with the sources of mineral resources.
- We’ll also see some examples of mineral resources.
- We’ll finish analysing the importance of mineral resources for human society development.
Mineral Resources Definition
A mineral is a naturally sourced, solid chemical compound with a crystalline structure.
A resource is goods or materials that are valuable and useful. Combine the two definitions together, and we have a mineral resource.
Mineral resources and eras of human technological advancement are intrinsically linked. Early human civilizations are divided into the Stone Age, the Bronze Age and the Iron Age. You may have also heard our current information technology era described as the silicon age.
Mineral Resource: A concentration of inorganic, naturally occurring, typically solid, non-renewable material with a practical use.
Minerals have a defined chemical composition, for example gypsum is also known as calcium sulfate dihydrate, or CaSO4·2H2O. Minerals are also categorized based on their unique physical properties, such as:
- Colour
- Density
- Lustre
- Streak
- Cleavage
- Hardness.
While the definition is straightforward, it doesn't exactly fit for all mineral resources.
- Most glaringly, oil is clearly categorized as a mineral resource, yet it is a liquid, and it comes from organic sources (decaying and buried organic matter).
- Limestone is also formed from organic sources (e.g. corals, bivalves, molluscs), and this arguably makes it renewable as well.
- Granite, for example, is essentially renewable, since new plutons are being formed below the Earth's crust every day.
Yet, at over millions of years to form new limestone or granite, the rate of renewal often outdates us so drastically that it cannot be truly considered renewable.
A mineral reserve is a mineral resource whose mining is economically viable. A mineral resource may be abundant, but mining the mineral it may cost more than its selling price. In this article, most mineral resources are assumed to also be a mineral reserve, but keep it mind this isn't always so.
Mineral Resources Types
Mineral resources are classified into distinct categories (Fig 1.). The first two major types of mineral resources, metallic and non-metallic, are based on the metal content of the mineral resource.
A metal is a solid mineral that is reflective, without a crystalline structure, malleable and electrically conductive.
A metal ore is a mineral, rock, or sediment that contains a concentrated and economically relevant amount of metal.
Metallic mineral resources are further split into two groups, ferrous and non-ferrous, based on whether the metal contains iron.
Rare earth elements (REE) are a special series of metallic non-ferrous mineral resources, in high demand because of their practical uses in our burgeoning modern electronic world.
Every so often, you may come across a separate category for a special subset of non-metallic mineral resources: fuel. As previously mentioned, fuels are generally pretty unique. Not only are they easily combustible, but they also barely fit our definition of mineral resource. They can be found in solid (coal), liquid (petroleum), or gaseous (natural gas) phases. Fuels are not inorganic, they are the product of decayed organic matter. Largely, fuels are non-renewable and naturally occurring, but this part of the definition is also tenuous. As we speak, engineers are hard at work trying to develop a method to extract natural gas from animal wastes. Nonetheless, fuels are still a mineral resource.
Sources of Mineral Resources
The source of almost all mineral reserves is the lithosphere, which is the upper part of the Earth's crust. As you will learn, there are three different geological sources that form mineral resources. The common link between these sources is that they transport and accumulate minerals.
We call the outer, solid part of the earth, the Lithosphere.
Magmatic Sources
Most mineral reserves are a direct result of magmatic bodies.
Magma is the molten rock material found in the mantle, below the lithosphere.
Magma chambers are immense subsurface cavities in the Earths crust (Fig. 2).
Eventually, a magma chamber stops being replenished with magma, and starts to cool down. During the slow cooldown phase, minerals form preferentially within the magma chamber, a process called crystal fractionation. Magma is the most common source of rare earth elements. Other minerals derived from magma are feldspar or mica minerals. Perhaps you own a granite countertop that was once a buried magma chamber.
Fig. 2. An illustration of two possible mechanisms, a) or b), of mineral formation in magma chambers. The steps c, d and e are similar for both processes.
Sedimentary Sources
There are numerous types of water bodies, and each yields their own unique mineral resources. Generally speaking, most water bodies will accumulate minerals as some form of sedimentary deposition. A small, quiet, inland lake, after being separated from a river, allows fine clay particles to settle, creating a clay mineral deposit. Evaporating saline lakes leave behind salt flats. These special minerals, evaporites (Fig. 3), can be harvested for gypsum, lithium, or table salt.
Evaporites: Horizontally placed rocks or minerals that are deposited after the evaporation of briny or saline waters.
Bogs are distinctly renowned for generating peat, which is the first step to coal formation. High velocity water bodies, such as rivers and streams, leave behind placer deposits. The river drops heavier materials, like gravel, or heavy metals such as gold, while carrying away all other finer materials such as sand, silt, and clay.
Fig. 3. A picture of the Uyuni salt flats in Bolivia. The evaporites at this location are a mix of sodium, potassium, lithium, and magnesium chlorides.
Hydrothermal Sources
Some minerals are created when water (hydro-) percolates downwards through the lithosphere, and reaches a heat source (-thermal). The water heats up, and is capable of dissolving more solute. The water eventually flows away from the heat source, carrying along dissolved chemicals. As the water cools down, the minerals precipitate out of solution, creating hydrothermal deposits. Here are three major hydrothermal sources for mineral reserves.
Sulphide Deposits
Sulphide deposits are a specific type of hydrothermal source (Fig. 4) found at tectonic plate spreading centres at the bottom of the ocean. Metal and sulphides are dissolved in ocean water near these hot spots. The dissolved minerals later precipitate out of solution when the solute reaches cooler ocean water.
Fig. 4. A hydrothermal vent in the Mariana Trench. Notice the yellowish brown features on this vent, which is indicative of sulphide minerals. NOAA Ocean Exploration.
Vein Deposits
Vein deposits are mineral reserves precipitated out of solution in the bedrock cracks around a magma chamber. These result in quartz and calcite veins, but also yield precious metals such as gold, silver, and copper. Occasionally, these mineral reserves can contain rare earth minerals.
Stratabound Deposits
Stratabound deposits are mineral reserves accumulated in a sedimentary rock layer, or strata. Sedimentary rock layers tend to have a high percentage of void space per volume, known as porosity. When thermally heated water flows through these rock layers, it may precipitate out minerals. Examples of stratabound deposits are the minerals containing lead, zinc, or copper metals.
Examples of Mineral Resources
Now that you have learned how to classify mineral resources, let's review some examples of minerals we humans are actively mining. The following table has sorted the examples of mineral resources by type in the vertical columns, and by source in the horizontal columns.
Source | Metallic | Non-metallic |
Ferrous | Non-Ferrous |
Magmatic | Illmenite Magnetite | Copper Platinum Chromium Nickel Lithium | Quartz Feldspar Mica Diamond |
Sedimentary | Magnetite, hematite & siderite (from Banded iron formations) Limonite | Aluminium (from Bauxite) Gold Zircon Uranium | Clay Gravel Fuel (coal, oil, natural gas) Diamond Table salt Gypsum Limestone Phosphate |
Hydrothermal | Sphalerite Hematite | Copper (from Chalcopyrite) Lead (from Galena) Zinc (from Sphalerite) Tungsten Gold Silver | Quartz Calcite Marble |
Table 1: Examples of mineral resources by type and source.
Importance of Mineral Resources
Now it is time to learn the importance of mineral resources and the impact these minerals have on our lives. Most importantly, and perhaps obviously, the mining of mineral resources supplies the raw materials we use to build the objects surrounding us. Combined with the use of technology, humankind has the uncanny ability to turn a shapeless lump into an object with an application. From the first wheels constructed out of stone during the Palaeolithic, all the way to nanocomputers and satellites, the importance of minerals as building blocks should be self-evident.
- Clay is used for pottery, bricks, and tiles.
- Metals are critical in the domains of industry, and transportation, and electronics.
- Gypsum is used to make plasterboard.
- Sand, soda ash and limestone are combined to manufacture glass.
- Plastics are derived from fossil fuels.
The list is endless.
Reach for any object near you and try to learn what mineral resources were required to create it. Almost every object you touch can be traced to one or more mineral reso! Find out where the mining of these minerals is occurring. Are the mineral reserves local, or from another country or continent?
Mineral resources that are directly used for construction, such as clay, stone, gypsum, sand or gravel, are categorized as construction minerals.
Industrial minerals, on the other hand, are the non-metallic mineral resources that are mined and modified after an industrial process, such as slate, talc, limestone or dolomite.
Furthermore, we have been able to extract energy out of mineral resources.
Early civilizations used oil and coal as a source of light or heat for metalworking. The combination of steam power and coal accelerated the development of civilization during the industrial revolution. Because of Wales and England's plentiful mineral reserves, the demand for coal mining launched the British Isles into a new dawn of civilization. For the past 100 years, fossil fuels have been the main source of energy for our larger modes of transportation, such as automobiles and aeroplanes. Nuclear energy employs radioactive minerals, mainly Uranium, to harness the energy released during nuclear fission. As our demand for electronics and electric vehicles increases, so does the demand for batteries and the lithium minerals that powers them.
We even ingest mineral resources! We use salt to accentuate a bland meal, and clays to thicken our milkshakes. After binging on salty snacks and sugary dairy treats, one must inevitably reach for the antacid, some of which are simply calcium carbonate, or calcite minerals. Further medical uses are talc as baby powder, pumice stone to remove calluses or plaster of Paris, derived from gypsum, to form casts around broken bones. Finally, phosphates mining leads to the enrichment of agricultural soils, which helps provide us with food.
Economically, mining these resources is important. The location of mineral reserves is geologically defined, and therefore not equitably distributed within geopolitical lines. There, harvesting these minerals has created its own mining economy where trading minerals between countries is crucial. Below is a map of England, showing the location of a few active mineral mining operations (Fig. 5).
Fig. 5 A map of England, showcasing the mining sites for some mineral resources.
Hopefully, you now know more about mineral resources. Next time you treat yourself to a portion of chips, think about the mineral resource that the saltiness came from.
Mineral Resources - Key takeaways
- A Mineral Resource is a concentration of inorganic, naturally occurring, typically solid, non-renewable material with a practical use.
- Types of metallic resources are metallic and non-metallic. Metallic mineral resources can be iron-bearing (ferrous) or not (non-ferrous).
- The sources of mineral resources are most commonly magmatic, sedimentary or hydrothermal.
- Examples of mineral resources are iron, diamond, gold, silver, copper, aluminium, granite, marble, clay, table salt, rare earth elements or fossil fuels.
- Mineral resources provide us with raw building materials for nearly most objects around us, as well as food, energy, or raw materials that enhance our health and agriculture.
References
- Fig. 2. Magma Chamber (https://upload.wikimedia.org/wikipedia/commons/1/1f/Magma_chamber.png) by Willem Kruger & Rais Latypov is licensed by CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)
- Fig. 3. Uyuni Salt Flats in Bolivia (https://unsplash.com/photos/OLc6qPfizeA) by Diego Aguilar (https://unsplash.com/@diego_aguilar) is licensed by Unsplash License (https://unsplash.com/license)
- Fig. 4. Hydrothermal Vent (https://flic.kr/p/2kSQknT) by NOAA Ocean Exploration (https://www.flickr.com/photos/oceanexplorergov/) is licensed by CC-BY-SA 2.0 (https://creativecommons.org/licenses/by-sa/2.0)
- Fig. 5. Distribution of Principal Industrial Mineral Workings (https://upload.wikimedia.org/wikipedia/commons/3/3a/Distribution_of_Principal_Industrial_Mineral_Workings.jpg) by DarkestElephant (https://commons.wikimedia.org/w/index.php?title=User:DarkestElephant&action=edit&redlink=1) is licensed by CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)
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