Chap 2 Atoms, Elements & Minerals

A set of vocabulary flashcards covering definitions of minerals, rocks, atoms, isotopes, bonding, mineral formation, silicate structures, and mineral identification terms from the notes.

Mineral

A naturally occurring, inorganic, crystalline solid with a definite chemical composition.

What is a Mineral

Naturally occurring – produced by geological processes

Generally inorganic – not from living things, no

hydrocarbons

Orderly crystalline structure – orderly arranged atoms

Solid – all minerals are solid, including ice, but not water

Definite chemical composition that allows for some

variation – most can be express by chemical formulas

Rock

A naturally formed aggregate of minerals or mineral-like matter; for example, granite is made of minerals.

rocks are composed of 

minerals

Minerals

are composed of atoms of elements

bonded together in an orderly crystalline structure

Atom

The basic unit of an element, consisting of a nucleus of protons and neutrons with electrons in orbit; electrically neutral when protons equal electrons.

Element

A substance defined by its atomic number (number of protons); 94 elements occur naturally.

Electrons

(− charged)

Protons

(+ charged)

Neutrons

(0 or = net charge)

Central Nucleus

is made of

• Protons (+ charged).

• Neutrons (0 net charge)

The Central Nucleus is

Surrounding Cloud of

• Electrons (− charged).

Isotope

Atoms of the same element with different numbers of neutrons, giving different atomic masses; can be stable or radioactive.

Stable isotopes

• Retain all their protons and neutrons through time, no decay

• • Stable isotopes of oxygen can be used to track climate change over time.

Unstable or radioactive isotopes:

• Spontaneously lose proton(s) and/or neutron(s) from

their nuclei over time, i.e. undergo radioactive decay

radioactive decay

The process by which unstable isotopes lose particles from their nuclei, resulting in the transformation into different atoms or isotopes and the release of energy.

Three primary types of bonds

» Ionic bond

» Covalent bond

» Metallic bond

Ionic bond

Bond formed by transfer of electrons from one atom to another, creating oppositely charged ions that attract.

Covalent bond

Bond formed by sharing valence electrons between atoms, forming stable molecules.

Metallic bond

Bond where valence electrons are delocalized in a 'sea' of electrons around metal ions, giving high conductivity.

Valence electron

Outermost electrons available for bonding; determine how an element bonds.

Precipitation (mineral formation)

Formation of solid minerals when a solution becomes saturated and ions bond.

Crystallization

Formation of minerals as a melt or solution cools or changes conditions, producing orderly crystals.

Allows Ingrown Crystal to form due to slow cooling or evaporation, resulting in well-defined geometric shapes.

Deposition

Process by which minerals are laid down from a carrier (solution or organism) forming mineral matter.

Silicate

Minerals built from SiO4 tetrahedra; the most abundant mineral group in Earth’s crust.

Nonsilicate

Mineral groups not based on silicate tetrahedra (e.g., carbonates, halides, oxides, sulfides, sulfates, phosphates).

Primary minerals

Minerals formed at high temperature/pressure, common in igneous and metamorphic rocks.

Secondary minerals

Minerals formed at surface conditions by weathering; often clays and hydrous oxides.

Quartz

SiO2; a framework silicate; hard (Mohs 7) and common in many rocks.

Feldspar

Family of framework silicates (orthoclase and plagioclase); major rock-forming minerals.

Olivine

Isolated-silicate structure (SiO4 tetrahedra); characteristic of ultramafic rocks.

Pyroxene

Single-chain silicate; example augite.

Amphibole

Double-chain silicate; example hornblende.

Mica

Sheet silicate minerals (e.g., biotite, muscovite); 2:1 structure with perfect cleavage.

Clay mineral

Layered silicate minerals common in soils (e.g., montmorillonite, illite).

Calcite

Carbonate mineral CaCO3; rhombohedral cleavage; effervesces with acid.

Dolomite

Carbonate mineral CaMg(CO3)2; similar to calcite but with magnesium.

Halite

Halide mineral NaCl; rock salt; cubic cleavage.

Hematite

Iron oxide Fe2O3; major ore of iron; often earthy to metallic luster.

Magnetite

Iron oxide Fe3O4; magnetic; important iron ore.

Galena

Lead sulfide PbS; ore of lead; metallic luster.

Sphalerite

Zinc sulfide ZnS; ore of zinc; can have resinous luster.

Chalcopyrite

Copper iron sulfide CuFeS2; ore of copper; brassy yellow color.

Native elements

Minerals consisting of a single element (e.g., gold, copper, diamond, graphite, sulfur).

Mohs hardness scale

A 1–10 scale ranking mineral hardness; 1 = talc, 10 = diamond.

Streak

Color of a mineral in powdered form; often more diagnostic than surface color.

Periodic Table

Organization of elements by similar properties into groups; symbols, atomic numbers and weights.

Noble gases

Inert group of elements (He, Ne, Ar, Kr, Xe, Rn) with very low reactivity.

Hydrogen isotopes

Protium (1H), Deuterium (2H), and Tritium (3H); isotopes with different mass numbers.

Oxygen isotopes

16O, 17O, 18O; used to infer past temperatures; 16O/18O ratio informs climate records.

Electron shell

Energy levels around the nucleus; first shell holds 2 electrons; subsequent shells up to 8.

Atomic number

Number of protons in an atom’s nucleus; defines the element.

Atomic weight

Average mass of an element’s atoms (relative atomic mass) used on the periodic table.

Isolated silicate structure

SiO4 tetrahedra not sharing oxygens; example: olivine.

Single chain silicate

Silicate structure where SiO3 units form single chains; example: pyroxene.

Double chain silicate

Silicate structure with two chains linked (Si4O11); example: amphibole.

Sheet silicate

Two-dimensional silicate layers (Si2O5); examples: micas and clays.

Framework silicate

Silicate structure where SiO4 tetrahedra share all oxygens to form a 3D network; examples: quartz, feldspars.

Specific Gravity

of a mineral is the ratio of the weight of the mineral to the weight of an equal volume of water

Cleavage

Plane of weak chemical bonds in

a crystal where it can break along perfect

planes.

Fracture:

The external form or shape of

crystals may be the result of fracture or of

growth.

» When a crystal grows in a liquid (magma or aqueous

fluid), its rapid growth directions become points and

its slow growing directions become faces.

» Uneven surface – irregular

» Smooth curves - conchoidal

» Splinter – splintery

» Fibers – fibrous fracture

Luster

is the reflectivity of a mineral,

quality and intensity of light reflected from

the surface: metallic or non-metallic.

Hardness is the ability of a mineral to resist

scratching. We use the Mohs' hardness scale

for field testing:

» 1. Talc 4. Fluorite 7. Quartz

» 2. Gypsum 5. Apatite 8. Topaz

» 3. Calcite 6. Orthoclase

» 9. Corudum 10. Diamond

Color

is simply the color of a mineral in

hand specimen, but tiny amounts of certain

elements like iron can strongly color a hand

specimen.