Process Mineralogy: Weeks 1–6 Flashcards

Vocabulary flashcards covering fundamental process mineralogy concepts, crystal chemistry, physical properties, ore mineralogy, XRD, and microanalytical beam techniques based on Weeks 1–6 lecture notes.

Process Mineralogy

The application of mineralogy and mineralogical techniques to mineral processing.

Mineralogy

The study of minerals.

Petrology

The study of rocks, which are composed of one or more minerals.

Ore Petrology

The specialized study of ore deposits and their rock-forming characteristics.

Mineral Liberation

The degree to which valuable mineral grains are freed from gangue or other surrounding minerals upon grinding.

Mineral

A naturally occurring inorganic solid with a highly ordered atomic arrangement (crystalline) and a definite, but not necessarily fixed, chemical composition.

Solid Solution

Compositional variation between fixed limits in a mineral, occurring when one atom or ion substitutes for another in its crystal structure.

Ore Minerals

Minerals that contain valuable components worth extracting, typically comprising native metals, sulphides, or oxides.

Gangue

The commercially non-valuable waste material accompanying ore minerals, consisting overwhelmingly of rock-forming minerals like silicates.

Silica Tetrahedron

The fundamental building block of silicates, consisting of a central silicon ion surrounded by four oxygen ions ($SiO_4^{4-}$).

Hydrous Silicates

Silicate minerals containing structural water as $OH^-$ groups (such as hornblende and muscovite) that release hydrothermal fluids upon high-temperature breakdown.

Native Metals

Minerals consisting of uncombined elemental metals, primarily representing precious metals like the gold group and platinum group elements.

Sulphides

Minerals composed of a metal combined with sulphur (or metalloids like As, Sb, Te, Bi), forming the primary ores for base metals.

Oxides

Minerals composed of metals combined with oxygen, serving as the principal ores for ferrous metals like Fe, Mn, Cr, and Ti.

Siderophile

Goldschmidt's element group that prefers concentrating in the metallic phase (native metal), including Au, Pt, Ni, Fe, and Os.

Chalcophile

Goldschmidt's element group that combines readily with sulphur to form sulphides, including Cu, Pb, Zn, Ni, and As.

Lithophile

Goldschmidt's element group that concentrates in silicate minerals, comprising major rock-forming elements like Si, Al, Mg, Ca, Na, and K.

Atmophile

Goldschmidt's element group consisting of elements that remain predominantly in the gaseous state or atmosphere.

Streak

The color of a mineral's powder produced when scraped across an unglazed porcelain plate, serving as a more consistent diagnostic property than bulk color.

Lustre

The visual appearance of a mineral's surface as light reflects off it, which is dictated by its atomic bonding type.

Cleavage

The tendency of a mineral to break along flat, predictable structural planes of atomic weakness in its crystal lattice.

Fracture

The uneven or irregular breakage of a mineral along directions other than established cleavage planes.

Mohs Scale

A relative 1-to-10 ranking scale measuring a mineral's scratch resistance, ranging from talc (1) to diamond (10).

Tenacity

The manner in which a mineral resists breaking, crushing, bending, slicing, or tearing (e.g., brittle, malleable, sectile, ductile, flexible, elastic).

Specific Gravity (S.G.)

The ratio of a mineral's density to the density of water at a standard temperature, numerically equivalent to density in $g\,cm^{-3}$.

Paramagnetic

A weak form of magnetism occurring in minerals with unpaired electrons, where atomic dipoles align only in the presence of an applied magnetic field.

Ferrimagnetic

A strong form of magnetism resulting from unequal antiparallel coupling of neighbouring atomic magnetic moments, as exhibited by magnetite and pyrrhotite.

Unit Cell

The smallest repeatable structural unit of a crystal lattice that contains all symmetry elements and defining atomic ratios of the mineral.

Miller Indices

A notation system $(hkl)$ representing crystal faces or internal atomic planes based on the reciprocal ratios of their crystallographic axis intercepts.

Polymorphs

Minerals that share identical chemical formulas but possess different crystal structures and physical properties (e.g., diamond and graphite).

Radius Ratio

The ratio of cation radius to anion radius ($R_{\text{cation}} / R_{\text{anion}}$), which dictates the coordination number and packing geometry in ionic solids.

Coordination Number

The number of immediate surrounding anions or atoms bonded to a central cation or atom within a crystal lattice.

Refractory Gold Ore

A gold ore in which gold is sub-microscopically trapped within sulphide lattices (like arsenopyrite or pyrite) and requires pre-treatment before cyanidation.

Gossan

An oxidized, iron-rich weathered surface outcrop of a sulphide orebody, typically containing goethite and haematite displaying characteristic boxwork textures.

Substitutional Solid Solution

A type of solid solution where one atom or ion directly replaces another on the same lattice site in a crystal structure.

Interstitial Solid Solution

A type of solid solution where extra atoms or ions occupy empty structural spaces or gaps between normal lattice sites.

Omission Solid Solution

A type of solid solution characterized by missing atoms or structural vacancies in the crystal lattice (e.g., pyrrhotite, $Fe_{1-x}S$).

Fineness

A numerical measure of gold purity in an alloy, calculated as $1000 \times \frac{\text{Au}}{\text{Au} + \text{Ag}}$.

Sulphosalts

Hydrothermal minerals containing metals combined with sulphur alongside metalloids like arsenic, antimony, or bismuth (e.g., enargite, $Cu_3AsS_4$).

Bireflectance

The optical property of an anisotropic mineral under uncrossed polars where its brightness or pastel color changes as the microscope stage is rotated.

Anisotropism

An optical property observed under crossed polars where non-cubic minerals display changes in brightness and color through 360 degrees of stage rotation.

Internal Reflections

A diagnostic optical phenomenon under crossed polars where light enters translucent minerals and reflects back out as a characteristic colored internal glow.

Relief (Polishing Hardness)

The height difference between adjacent soft and hard mineral grains on a polished section, created due to differential wear during polishing.

Bragg's Law

The fundamental diffraction equation $n\lambda = 2d\sin(\theta)$ relating X-ray wavelength $\lambda$, incident angle $\theta$, and lattice interplanar spacing $d$.

Powder Diffraction File (PDF)

A standard reference databank of mineral d-spacings and X-ray peak intensities maintained by the ICDD for phase identification.

Back-Scattered Electrons (BSE)

High-energy beam electrons elastically bounced off atomic nuclei in an SEM, yielding image brightness proportional to mean atomic number ($\bar{Z}$).

Secondary Electrons (SE)

Low-energy surface electrons ejected during electron beam collision, used in SEM imaging to reveal fine surface topography.

Energy Dispersive Spectroscopy (EDS)

An analytical SEM method that rapidly identifies elements across a full spectrum by measuring the energy of emitted characteristic X-rays.

Wavelength Dispersive Spectroscopy (WDS)

A high-resolution microprobe technique that separates characteristic X-rays by diffractive wavelength using monochromator crystals, achieving detection limits below $100\,\text{ppm}$.

Secondary Ion Mass Spectrometry (SIMS)

An ultra-sensitive analytical tool using a primary ion beam ($Cs^+$ or $O^-$) to sputter secondary ions, capable of detecting sub-ppm trace elements like invisible gold.

QEMScan / MLA

Automated SEM-based image analysis systems used in mineral processing to measure mineral proportions, grain sizes, and liberation quantitatively.