Mineral properties have significantly impacted human society in various ways throughout history. They have been crucial in the construction of buildings, roads, and bridges, with materials like limestone, gypsum, and granite providing durability and accessibility for lasting infrastructure. The extraction and trade of minerals such as coal, gold, and copper have driven economic growth in many regions, creating jobs and stimulating local economies, though this can sometimes lead to economic inequality and environmental degradation—which we will get to in later posts.
Additionally, minerals are essential for modern technology; elements like silicon and rare earth metals are pivotal in the development of advanced electronics, enabling renewable energy conversion, and providing state-of-the-art materials to fostering innovation and collaboration.
Culturally, certain minerals and gemstones carry significant symbolism; for instance, gold is often associated with wealth and status, while diamonds, rubies, and even rocks (like Stone Henge) are treasures valued in jewelry and ceremonies. From a health perspective, minerals are vital for human nutrition and well-being, influencing health outcomes across societies. Examples include ferrihydrite (iron carrier in our bodies), apatite (our bones), and even pharmaceuticals are made from minerals.
Furthermore, the availability and control of mineral resources can shape geopolitical dynamics, as countries rich in specific minerals may exert significant influence, leading to competition and conflict. Overall, minerals have shaped human societies in myriad ways, affecting daily life, health, economics, and politics.
But before we take a deeper dive into those important implications of mineral resources, we first have to know some things about what we look for in minerals and how to identify them.
Color is a key property, with minerals used as pigments in paints. Mineral-based pigments are favored for their long-lasting color. However, some minerals can change color over time due to reactions with water and oxygen, such as malachite which changes from green to black. The Getty Museum uses a Fadometer to study how pigments fade, aiding in art restoration. Luster, another important property, refers to how light reflects off a material and includes descriptions like glassy, waxy, greasy, and metallic.
Streak, the color of a mineral when powdered, is often more diagnostic than the mineral's color itself. For example, hematite appears metallic, but has a blood-red streak. Hardness, the resistance to scratching, is a well-known property, with diamonds being the hardest naturally occurring material. Because of their hardness, diamonds are used in jewelry, as well as in industrial applications such as cutting tools. In contrast, toughness, which is different from hardness, refers to a material's ability to resist breaking, with carbonado diamonds known for their exceptional toughness. Carbonados are porous and the origin of formation is currently unknown.
Cleavage is a property where a crystal breaks along flat planes due to inherent weaknesses, as seen in minerals like mica and salt. Graphite also exhibits cleavage and is used in pencils and lubricants. Fracture is a random break through a crystal without any inherent planes of weakness. There are different types of fracture, such as splintery and conchoidal. Conchoidal fracture, where shock waves propagate through the crystal, is used in flintknapping. Crystal habit, which is the shape of a crystal such as cubic or hexagonal, is used to identify minerals.
Reactivity, often measured by how easily a mineral reacts with acids, affects a rock's longevity, with silicates being less reactive than calcites. Density is the weight per unit volume, and while useful, it is not often used in the field because rocks often contain varied mineral compositions. Additional mineral properties include piezoelectricity, where chiral crystals bend under electric current and are used in watches, pleochroism, where a mineral’s color changes based on the direction of light, as seen in tanzanite and is useful in asbestos analysis, and radio wave conversion, where high silver galena can convert AM radio waves to physical movement.
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