Soil minerals form the backbone of our planet's fertile ground. From to clay, these tiny particles shape soil's ability to support life. Understanding their properties and roles is key to unlocking the secrets of soil health and plant growth.
Primary minerals like quartz and weather into secondary minerals like clay. This transformation changes soil texture, nutrient content, and water-holding capacity. Together, these minerals create the dynamic environment where plants thrive and ecosystems flourish.
Primary Soil Minerals
Common soil minerals and sources
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Soil Formation – Soils Laboratory Manual View original
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2.4 Silicate Minerals – Physical Geology View original
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Soil Formation – Soils Laboratory Manual View original
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Top images from around the web for Common soil minerals and sources
Soil Formation – Soils Laboratory Manual View original
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5.4 Weathering and the Formation of Soil – Physical Geology View original
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2.4 Silicate Minerals – Physical Geology View original
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Soil Formation – Soils Laboratory Manual View original
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Primary minerals
Quartz dominates many soils withstands found in sand and silt fractions (beaches, deserts)
Source: igneous and metamorphic rocks break down into soil particles
Feldspars comprise about 60% of Earth's crust provide essential nutrients (potassium, calcium)
Orthoclase releases potassium during weathering
Plagioclase contributes calcium and sodium to soil solution
Source: igneous rocks form basis for many soil types (granite, basalt)
Micas form flat, sheet-like particles influence soil structure
dark-colored mica rich in iron and magnesium
light-colored mica contains potassium and aluminum
Source: igneous and metamorphic rocks weather into soil components
chain silicate minerals contribute iron and magnesium
common in soils derived from igneous rocks
Source: igneous and metamorphic rocks break down during soil formation
important source of calcium, magnesium, and iron in soils
Augite weathers rapidly releases nutrients
Source: igneous rocks especially prevalent in volcanic soils
Secondary minerals
result from weathering of primary minerals crucial for soil fertility
low shrink-swell capacity common in highly weathered soils (tropical regions)
moderate CEC retains potassium
high shrink-swell capacity forms expansive soils (Vertisols)
high CEC important for nutrient retention
Source: weathering of primary minerals through various processes
Iron and aluminum oxides influence soil color and phosphorus fixation
gives red color to soils (terra rossa)
Goethite responsible for yellowish-brown soil colors
common in highly weathered tropical soils
Source: weathering of iron and aluminum-bearing minerals under oxidizing conditions
Mineral weathering in soil formation
Physical weathering breaks down rocks without changing chemical composition
Freeze-thaw cycles expand water in cracks causing rock fragmentation
Root pressure exerts force on rocks as plants grow
Thermal expansion and contraction causes rock stress and fracturing
Chemical weathering alters mineral composition through reactions
breaks down minerals through reaction with water (feldspar to clay)
changes mineral state through exposure to oxygen (iron rusting)
removes minerals as they dissolve in water or acids (limestone in caves)
Biological weathering accelerates mineral breakdown through organism activity
release organic acids that dissolve minerals
Microbial activity produces CO2 and organic acids enhancing weathering
Mineral transformation alters existing minerals and forms new ones
Alteration of primary minerals changes their structure and composition
Formation of secondary minerals creates new soil components
Clay mineral synthesis builds complex layered structures
Precipitation of oxides and hydroxides forms distinct mineral phases
Soil Mineral Properties and Functions
Soil minerals' influence on properties
affects soil's ability to hold and release nutrients
Clay minerals and organic matter contribute to CEC through negative surface charges
Affects nutrient retention and availability for plant uptake
Soil structure impacts water movement and root growth
Clay minerals influence aggregation by binding soil particles
Impacts water retention and aeration in soil pores
Soil pH determines nutrient availability and microbial activity
Buffering capacity of clay minerals stabilizes soil pH
Affects nutrient availability by influencing solubility and ion exchange
Water holding capacity determines soil moisture retention for plant use
Clay content influences soil moisture retention through small pore spaces
Nutrient supply provides essential elements for plant growth
Weathering of primary minerals releases elements (potassium, calcium, magnesium)
Soil color indicates soil composition and conditions
contribute to soil color (red, yellow, brown hues)
Soil plasticity and cohesion affect soil workability and erosion resistance
Clay minerals affect soil physical properties through particle interactions
Primary vs secondary mineral roles
Primary minerals form foundation of soil composition
Serve as parent material for secondary minerals through weathering processes
Slowly release nutrients through gradual breakdown (potassium from feldspars)
Contribute to soil texture by forming sand and silt fractions
Generally have lower surface area and reactivity compared to secondary minerals
Secondary minerals dominate soil chemical processes
Higher surface area and reactivity due to small particle size and complex structures
Dominate soil chemical processes through ion exchange and adsorption
Major contributors to CEC enhancing nutrient retention
Influence soil pH and buffering capacity stabilizing soil chemistry
Play crucial role in nutrient cycling and retention for plant availability
Affect soil structure and water-holding capacity improving soil physical properties
More susceptible to environmental changes (pH, redox conditions)