mineralogy - final

colloid

mixture of substances small enough to not settle out of water, even if water is moving

reduction potential

measure of the tendency of chemical species to acquire electrons and be reduced (more negative = more favorable adding e^-)

oxidation

loss of electrons or increase in oxidation state

inner sphere complex

cation is bound, forms a direct covalent bond with oxygen on the surface (tightly bound)

outer sphere complex

electrostatic attraction, cation not directly bound to surface (more easily mobilized)

X-ray diffraction

study structure of materials at atomic level by analyzing patterns produced when X-rays are scattered by crystal lattice of sample

Bragg’s law

describes relationship between spacing of atomic planes in a crystal and its angles of X-ray diffraction (n𝛌 = 2dsin𝜭)

pH

figure expressing acidity of solution on log scale ([pH] = -log₁₀[H⁺])

ternary diagram

graphical representation of the ratio of 3 variables which sum to a constant

Pourbaix diagram

plot of minerals with lowest Gibbs free energy, shows thermodynamically stable phases of chemical species in an aqueous solution by comparing pH to Eh (voltage)

hydrolysis

chemical breakdown of a compound due to reaction with water

phase rule

number of minerals in a rock or mineral assemblage does not exceed number of chemical components present (F=C - P + 2)

permeable reactive barriers

subsurface structure designed to treat contaminated groundwater as it flows through

asbestiform

any mineral crystal with a length much longer than its width

239-Pu

fissile isotope of plutonium primarily used in nuclear weapons and reactors with a half-life of approximately 24,000 years

reduction

chemical reaction where substance gains electrons and decreases its oxidation number

Latimer diagram

representation of standard electrode potentials of a series of related redox reactions (most oxidized on left)

sorption

attraction and adhesion of ions from an aqueous solution to a solid surface

point of zero charge

pH value at which surface charge density of a mineral surface becomes zero

asbestos

regulatory term for 6 minerals (chrysotile + 5 amphiboles) that are asbestiform

tailings

materials left over after extraction of valuable minerals from ore during mining operations

rare earth elements

set of 17 chemically similar metallic elements (lanthanides + Sc + Y) found in the Earth’s crust; used for energy, technology, defense, etc.

dominant chemical reactions in production of AMD

1. FeS₂ + 7/2 O₂ + H₂O → Fe²⁺ + 2 SO₄^2- + 2 H⁺

2. Fe²⁺ + ¼ O₂ + H⁺ → Fe³⁺ + ½ H₂O

3. Fe³⁺ + 3 H₂O → Fe(OH)_3(solid) + 3 H⁺

coal mine waste

waste generated during coal extraction and processing before combustion

coal ash waste

residue left after burning coal for electricity, including fly ash (PM)

radioactive remediation

process to reduce or eliminate radiation exposure from contaminated land and water

zeolite

tectosilicate mineral with aluminosilicate framework whose porosity and loosely bound cations allow for ion exchange + adsorption

bentonite

clay-rich aluminosilicate with low permeability, self-sealing properties, and exchangeable cations (high sorption)

manganese nodules

metal-rich rocks containing valuable metals (iron, manganese, etc.) that lie on the ocean floor and grow concentrically around a nucleus

hydrogenetic

metals precipitate from seawater

diagenetic

metals rise from sediment pore waters

lanthindes

group of 15 REEs from La to Lu

enhanced rock weathering

spreading of finely crushed silicate rocks on land to accelerate natural weathering and remove CO₂

ocean acidification

lower pH in ocean caused by uptake of atmospheric CO₂ by seawater

inorganic carbonate minerals

precipitate directly from water saturated with carbonate ions, forming deposits

organic carbonate minerals

form through accumulation of Ca shells and skeletons of marine organisms

saturation state

ratio of action ion concentration product in solution to mineral’s solubility product

lithium ion battery

rechargeable battery that stores and releases energy by reversible movement of lithium ions between 2 electrodes

coastal erosion

loss of coastal land due to wave action, currents, tides, storms, and sea-level rise

acid mine drainage

acidic water produced when sulfide minerals exposed by mining are oxidized, producing sulfuric acid and mobilizing metals

pyrite

(FeS₂) when oxidized, produces sulfuric acid and releases Fe²⁺ and sulfate; most influential for AMD

piezoelectricity

electric potential difference generated when minerals undergo compression or stretching

quartz as a piezoelectric mineral

no center of symmetry → compression creates electric dipole → potential difference results in electric field

perthite

worm-like texture formed by slow cooling of alkali feldspar created by exsolution of Na and K regions

twinning

growth error where crystals start to grow in other direction

Tartan twinning

zebra-like stripes that form because Al-Si ordering (high T, low order, high symmetry) among tetrahedral sites lowers feldspar symmetry to triclinic, forcing the crystal to twin to accommodate structural strain

What are methods for uranium remediation?

• reducing UO₂²⁺ to UO₂

• adsorption and sorption onto phosphates and clay minerals

• adding phosphates to form stable uranyl phosphates

• removal through excavation

How does Iron Mountain remediate?

uses partial capping, surface water diversions, tailings removal, neutralization, metal removal

intrinsic bond

Pu bonds to itself to make colloidb

natural bond

Pu bonds to other particles to make colloid

calcite

6-fold coordinated Ca in trigonal structure

aragonite

9-fold coordinated Ca in an orthorhombic structure

soluble oxidation state of U

+6

soluble oxidation state of Np

+6

soluble oxidation state of Pu

+5/+6

soluble oxidation state of Tc

+7

soluble oxidation state of I

+7

coordination environment about U in uraninite

cubic, coordination #8

coordination environment about O in uraninite

tetrahedral, coordination #4