Minerals Can Be Divided Into

The Diverse World of Minerals: A Comprehensive Classification

Minerals are the fundamental building blocks of rocks and the Earth's crust. Understanding how these naturally occurring, inorganic solids are classified is crucial to comprehending geology, geochemistry, and even material science. This article delves into the intricate ways minerals can be divided, exploring the various classification schemes and the underlying principles that govern them. We'll cover chemical composition, crystal structure, and other defining characteristics, ensuring a comprehensive understanding of this fascinating subject.

Introduction: Why Classify Minerals?

Before diving into the specifics, let's understand why we classify minerals. A systematic classification isn't just about organization; it provides a framework for:

• Predicting Properties: Knowing a mineral's classification often allows us to predict its physical and chemical properties, such as hardness, cleavage, density, and reactivity.
• Understanding Formation: Classification helps us understand the geological processes that led to the mineral's formation, providing insights into the Earth's history and evolution.
• Resource Exploration: Classifying minerals is essential for exploration and extraction of economically valuable resources, such as ores containing valuable metals.
• Scientific Research: A consistent classification system facilitates communication and collaboration among geologists, mineralogists, and other scientists working with minerals.

Primary Classification: Based on Chemical Composition

The most widely used and fundamental classification scheme for minerals is based on their anionic groups – the negatively charged ions that dominate their chemical structure. This approach groups minerals with similar chemical bonding and often similar physical properties. The main classes under this scheme include:

1. Silicates: This is the largest and most abundant class of minerals, comprising over 90% of the Earth's crust. Silicates are characterized by the presence of the silicate anion (SiO₄)⁴⁻, which can link together in various ways to form chains, sheets, frameworks, and other complex structures. Examples of silicate minerals include:

• Nesosilicates (Orthosilicates): These have isolated SiO₄ tetrahedra. Examples include olivine, garnet, and zircon. Olivine, for instance, is a crucial mineral in the Earth's mantle.
• Sorosilicates: These contain pairs of linked SiO₄ tetrahedra. Examples include epidote and hemimorphite.
• Cyclosilicates (Ring Silicates): These feature rings of SiO₄ tetrahedra. Tourmaline is a well-known example, prized for its vibrant colors.
• Inosilicates (Chain Silicates): These have chains of SiO₄ tetrahedra. Pyroxenes (e.g., augite) and amphiboles (e.g., hornblende) are important examples, often found in igneous and metamorphic rocks.
• Phyllosilicates (Sheet Silicates): These possess sheets of SiO₄ tetrahedra. This group includes the clay minerals (kaolinite, montmorillonite) and micas (muscovite, biotite), crucial components of sedimentary and metamorphic rocks.
• Tectosilicates (Framework Silicates): These have three-dimensional frameworks of SiO₄ tetrahedra. This is the most abundant subclass, encompassing quartz, feldspars (orthoclase, plagioclase), and zeolites. Quartz, known for its crystalline structure and hardness, is a ubiquitous mineral.

2. Oxides: These minerals consist of metal cations bonded to oxide anions (O²⁻). Many important ores are oxides, including those of iron (hematite, magnetite), aluminum (corundum), and chromium (chromite). Hematite, a significant iron ore, is responsible for the red color of many soils and rocks.

3. Sulfides: These minerals contain metal cations bonded to sulfide anions (S²⁻). Many important metal ores belong to this class, such as pyrite ("fool's gold"), galena (lead sulfide), and chalcopyrite (copper iron sulfide). Sulfides are often associated with hydrothermal veins and volcanic activity.

4. Sulfates: These contain metal cations bonded to sulfate anions (SO₄)²⁻. Gypsum and anhydrite, important evaporite minerals, are common examples. Gypsum is used extensively in plaster and drywall production.

5. Halides: These are minerals containing halide anions (F⁻, Cl⁻, Br⁻, I⁻) bonded to metal cations. Halite (sodium chloride, or table salt) and fluorite (calcium fluoride) are prominent examples. Halite is a crucial mineral for human consumption and industrial use.

6. Carbonates: These minerals contain the carbonate anion (CO₃)²⁻. Calcite (calcium carbonate) and dolomite (calcium magnesium carbonate) are the most abundant examples, forming limestone, marble, and dolostone. Calcite is a major component of many marine organisms' shells and skeletons.

7. Phosphates: These contain the phosphate anion (PO₄)³⁻. Apatite, an important source of phosphorus for fertilizers, is a key example.

8. Tungstates, Molybdates, Vanadates: These less abundant classes contain anions derived from tungsten, molybdenum, and vanadium respectively. These minerals are often associated with hydrothermal deposits and are sources of valuable metals.

9. Native Elements: This class encompasses minerals that consist of a single element, such as gold (Au), silver (Ag), copper (Cu), sulfur (S), and diamond (C). These minerals occur in their pure form, often in veins or placer deposits.

Secondary Classifications: Beyond Chemical Composition

While chemical composition forms the backbone of mineral classification, other factors also play a significant role:

1. Crystal Structure: The arrangement of atoms in a mineral's crystal lattice is critical. Minerals with the same chemical composition but different crystal structures are called polymorphs. For example, diamond and graphite are both composed of carbon but have vastly different structures and properties due to the different bonding arrangements.

2. Physical Properties: Many physical properties, such as hardness (Mohs hardness scale), cleavage, fracture, luster, color, and density, are used to identify minerals. These properties are often directly linked to the mineral's chemical composition and crystal structure.

3. Genesis (Mode of Formation): Minerals can form through various geological processes: igneous (from cooling magma), sedimentary (from precipitation or deposition), metamorphic (from transformation under high pressure and temperature), and hydrothermal (from hot aqueous solutions). Understanding the genesis provides valuable insights into the mineral's history and environment of formation.

The Importance of Mineral Identification

Accurate mineral identification is crucial across many disciplines:

• Geology: Understanding mineral assemblages helps determine the age, origin, and evolution of rocks.
• Mining and Exploration: Identifying minerals with economic value is essential for resource extraction.
• Environmental Science: Mineral composition impacts soil fertility, water quality, and environmental remediation strategies.
• Material Science: Minerals are used as raw materials in various industrial applications, from construction to electronics.

Frequently Asked Questions (FAQ)

Q: Can a mineral belong to more than one class?

A: No, minerals are typically assigned to a single class based on their dominant anionic group. However, some minerals may exhibit characteristics of multiple classes, making their classification challenging.

Q: What is the difference between a rock and a mineral?

A: A mineral is a naturally occurring, inorganic solid with a definite chemical composition and ordered atomic arrangement (crystal structure). A rock is a naturally occurring solid aggregate of one or more minerals.

Q: How are new minerals discovered?

A: New minerals are discovered through careful analysis of their chemical composition, crystal structure, and physical properties. Advanced techniques like X-ray diffraction are crucial for this process.

Q: Is there a universal agreement on mineral classification?

A: While the chemical composition-based classification is widely accepted, there are some variations and ongoing debates, particularly in dealing with complex or unusual minerals.

Conclusion: A Continuing Journey of Discovery

The classification of minerals is a dynamic field that continues to evolve as our understanding of the Earth and its materials deepens. This article provided a comprehensive overview of the primary and secondary classifications, highlighting the importance of this system for scientific research, resource management, and various other applications. Remember, the seemingly simple act of classifying minerals unlocks a world of knowledge about our planet's history, composition, and potential. Continued exploration and refinement of classification schemes will further illuminate the diverse and fascinating realm of minerals, fostering new discoveries and deepening our understanding of the Earth’s dynamic systems.