Soil Formation and Mineralogy Practice Flashcards

Vocabulary practice flashcards covering Soil Mechanics Chapter 1: Soil Formation and Mineralogy.

Geotechnical Engineering

A field focusing on the engineering aspects of soils and rocks for the development and stability of civil engineering projects.

Soil Mechanics

The study of the application of forces and equilibrium as they pertain to soils and rocks and how soil masses behave under loading.

Soil Engineering

The transition of soil mechanics concepts into practical solutions for real-world engineering problems related to soil behavior.

Foundation Engineering

A branch of engineering dealing with the use of soil mechanics to design earth and earth-supported structures like buildings and dams.

Soil (Engineering Definition)

The uncemented aggregate of mineral grains and decayed organic matter (solid particles) with liquid and gas in the empty spaces.

Pore Water

The liquid phase of soil, primarily water, which influences weight, effective stress, strength, and settlement.

Gas Phase

The portion of soil, mostly air, that fills the void space not occupied by water, affecting drainage and aeration.

Weathering

The natural process through which rocks are broken down into smaller fragments by mechanical and chemical actions.

Mechanical Weathering

The breaking down of rocks into smaller pieces without a change in mineral composition; also known as physical weathering.

Abrasion

The wearing away of rock surfaces by the impact of sand grains carried by the wind, acting like sandpaper.

Attrition

The wearing down of sand grains themselves as they collide with each other during transport.

Exfoliation

The peeling or flaking off of outer rock layers due to expansion and contraction or the release of overlying pressure.

Frost Wedging

A process where water freezes in rock cracks, widening and deepening them until pieces break off.

Frost Heaving

Upward pressure created in soil and rock when water freezes, contributing to fragmentation.

Chemical Weathering

The weakening and subsequent disintegration of rock by chemical reactions like oxidation, hydrolysis, and carbonation.

Oxidation

The reaction of rock minerals with oxygen, changing mineral composition and making them less resistant to weathering.

Carbonation

The process of rock minerals reacting with carbonic acid, which is formed when water combines with carbon dioxide.

Hydrolysis

A chemical reaction caused by water that changes the chemical composition and size of minerals in rock.

Hydration

The absorption of water into the mineral structure, such as the formation of gypsum from anhydrite.

Dehydration

The removal of water from rock or mineral structures, such as the formation of hematite from limonite.

Biological Weathering

The disintegration of rock caused by the activities of plants, animals, and microbes.

Lichen

A symbiosis of fungi and algae that releases chemicals to break down rock minerals.

Residual Soils

Soil products of weathering that stay in the same place where they were formed.

Transported Soils

Soil products of weathering moved to other places by ice, water, wind, or gravity.

Glacial Soils

Soils formed by the transportation and deposition of glaciers.

Alluvial Soils

Soils transported by running water and deposited along streams.

Lacustrine Soils

Soils formed by deposition in quiet lakes.

Marine Soils

Soils formed by deposition in the seas.

Aeolian Soils

Soils transported and deposited by the wind.

Colluvial Soils

Soils formed by the movement of soil from its original place by gravity, such as during landslides.

Organic Soil

Soil typical of low-lying, coastal, or glaciated areas with moisture content ranging from $200$ to $300\%$.

Secondary Consolidation

The process responsible for a large amount of settlement in organic soils under loads.

Boulder Clay

An unstratified mixture of clay and rock fragments of all sizes.

Calcareous Soil

Soil that contains calcium carbonate.

Conglomerate

Cemented sand and gravel.

Dispersive Clay

A clay that is easily erodible under low-velocity water.

Fat Clay

Highly plastic clay.

Hardpan

A very dense soil layer, often cemented, that is difficult to excavate.

Loam

A mixture of sand, silt, and clay used as topsoil.

Loess

Uniform silt-sized wind-blown deposits.

Laterite

Red-colored residual soil found in the tropics.

Reactive Clay

Expansive clay that swells when in contact with water.

Varved Clay

Thin alternating layers of silts and fat clays of glacial origin.

Soil Mineralogy

The study of inorganic minerals found in the pedosphere to the depth of weathering.

Minerals

Naturally occurring inorganic crystals with a definable range of chemical composition and a regular repeating atomic pattern.

Rock Fragments

Mineral composites made up of physical mixtures of several individual minerals, found among sand-size particles and larger.

Primary Minerals

Minerals derived directly from geological and geochemical processes in the Earth’s crust.

Secondary Minerals

By-products of chemical weathering formed through alteration of primary minerals or chemical precipitation.

Metallic Minerals

Minerals that exhibit luster and consist of metals in their chemical composition.

Non-Metallic Minerals

Minerals that show a non-metallic luster and do not contain extraction metals.

Crystal Systems

A method of classifying crystals according to their atomic lattice or structure.

Cubic (Isometric) System

A system where all three axes are of equal length and intersect at right angles.

Trigonal (Rhombohedral) System

A system where all three axes are of equal length, none are perpendicular, but faces have the same size and shape.

Tetragonal System

A system with three axes at right angles, two of which are equal in length while one is different.

Orthorhombic System

A system where all three axes are unequal and are at right angles to each other.

Hexagonal System

A system with four axes: three on one plane at $120^{\circ}$ and a fourth perpendicular of a different length.

Monoclinic System

A system where all three axes are unequal and only two are perpendicular.

Triclinic System

A system where all three axes are unequal in length and none are perpendicular to another.

Tenacity

Describes how mineral particles hold together or resist separation when subjected to stress.

Brittle

A material that breaks or fractures suddenly without significant deformation when stressed.

Sectile

A material that can be cut smoothly with a knife or sheared without crumbling.

Malleable

A material that can be deformed or shaped by hammering without cracking.

Ductile

A material that can undergo significant plastic deformation by stretching without breaking, often into wires.

Flexible but inelastic

A material that can bend without breaking but does not return to its original shape (permanent deformation).

Flexible and elastic

A material that can bend and return to its original shape after stress is removed.

Hardness

Measurement of the difficulty with which a smooth surface of a mineral may be scratched.

Mohs Scale 1

Hardness value assigned to Talc.

Mohs Scale 2

Hardness value assigned to Gypsum.

Mohs Scale 3

Hardness value assigned to Calcite.

Mohs Scale 4

Hardness value assigned to Fluorite.

Mohs Scale 5

Hardness value assigned to Apatite.

Mohs Scale 6

Hardness value assigned to Orthoclase.

Mohs Scale 7

Hardness value assigned to Quartz.

Mohs Scale 8

Hardness value assigned to Topaz.

Mohs Scale 9

Hardness value assigned to Corundum.

Mohs Scale 10

Hardness value assigned to Diamond.

Fracture

Describes how a mineral breaks creating rough, jagged, or curved lines rather than splitting along flat planes.

Conchoidal Fracture

A type of mineral break that occurs along smooth curved surfaces.

Fibrous Fracture

A type of mineral break that looks similar to wood.

Hackly Fracture

Jagged fractures with sharp edges.

Uneven Fracture

Rough, irregular surfaces produced during a mineral break.

Cleavage

The splitting of a crystal between two parallel atomic planes.

Streak

The color produced by a fine powder of mineral when scratched on a streak plate.

Luster

The general appearance of a mineral surface in reflected light, classified as metallic or non-metallic.

Vitreous Luster

A glassy, shiny surface appearance.

Resinous Luster

An amber-like, glossy appearance.

Pearly Luster

A soft, iridescent sheen appearance.

Greasy Luster

A slick, oily look on a mineral surface.

Silky Luster

A fine, fibrous shimmer appearance.

Adamantine Luster

A brilliant, diamond-like sparkle.

Density

The mass per unit volume of a mineral.

Color (Mineral property)

Attributes caused by selective absorption and reflection of wavelengths when white light interacts with crystal structure.

Feldspars

Aluminosilicate minerals containing Ca, Na, or K, making up over half of Earth's crust.

Quartz

Silicon dioxide ($SiO_2$), the second most abundant mineral in the Earth's crust.

Amphibole

Silicate minerals with two distinctive cleavage directions at approximately $56^{\circ}$ and $124^{\circ}$.

Mica

Hydrous potassium, aluminum silicate minerals with perfect cleavage into thin, elastic sheets.

Olivine

Important group of rock-forming minerals named after members of the forsterite-fayalite solid-solution series.

Garnet

Dodecahedron or trapezohedron crystals lacking cleavage, often used as abrasives due to hardness.

Calcite

The most common form of calcium carbonate, ranked number 3 on the Mohs hardness scale.

Pyroxene

Ferromagnesian silicate minerals with stubby prismatic crystals and cleavage angles of about $87^{\circ}$ and $93^{\circ}$.