Rocks & Minerals - ESci 1st Sem

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Characteristics of Minerals

• Naturally Occuring

• Inorganic

• Solid

• Definite Chemical Composition

• Ordered internal Structure

Why is pearl not a mineral?

Pearls are organic, produced by living organisms (mollusks) and lack a definite crystalline structure.

What substances are not considered minerals due to their state of matter?

water & petroleum are not considered minerals because they are liquid at standard temperature and pressure.

Exception in definite chemical composition

atomic substitution— characteristics of certain minerals

Ordered internal Structure

organized in a regular, repetitive geometric pattern or crystal structure.

How are minerals FORMED

• Crystallization from magma/Lava

• Precipitation from water

• Changes in Temperature and Pressure (Metamorphism)

• Formation from Hydrothermal Solutions

Magma slowly cools underground: __________ ; Lava cools quickly on surface:__________

Large Crystals, glassy ; Small/No crystals, dull & earthy

Diamond

hardest mineral

Precipitation from Water

dissolved substances in water become concentrated and crystallize. Evaporation of salty water leaves behind crystals.

Changes in Temperature and Pressure other term

Metamorphism

Changes in Temperature and Pressure (Metamorphism)

underground heat and pressure can change existing minerals into new ones without melting.

Formation from Hydrothermal Solutions

Hot water rich in minerals flows through cracks and cools, depositing minerals.

Superheated water + minerals → _______

deposits in veins

Composition of Minerals

elements abundant on Earth’s crust

Composition of Minerals

• Silicates

• Oxides

• Sulfides

• Sulfates

• Halides

• Carbonates

• Native Metals

Silicates

silicon-oxygen tetrahedrons (SiO₄⁴⁻) ; major rock-forming minerals.

Ex. olivine ((Mg,Fe)₂SiO₄), quartz (SiO₂)

Oxides

metal cations bonded to oxygen anions

Ex. magnetite (Fe3O4), hematite (Fe2O3)

Sulfides

a metal or semi-metal cation bonded to sulfide (S²⁻)
Ex. galen (PbS) and pyrite (FeS2)

Sulfates

metal cation bonded to sulfate ions (SO4²⁻) ; precipitate out of water near Earth’s surface.

Ex. gypsum (CaSO₄·2H₂O)

Halides

Halogen ion

Ex. rock salt (NaCl) and fluorite (CaF2)

Carbonates

presence of the carbonic ion (CO32-) which bonds elements such as calcium or magnesium to form calcite (CaCO3) or dolomite (CaMg(CO3)2)

Native Metals

Single Metal

Ex. copper (Cu) and gold (Au)

Six Crystal systems in grouping minerals based on structure

triclinic, monoclinic, orthorombic, tetragonal, hexagonal, and isometric structures

Crystal Structure

dependent on the chemical composition of the mineral

PHYSICAL PROPERTIES

• crystal formation

• habit

• cleavage

• fracture

• luster

• color

• streak

• hardness

• density

• magnetism

• taste

• feel

• reaction to acid

Crystal Habit

general appearance or growth style of a crystal

Crystal Form

the specific geometric arrangement of crystal faces.

Crystals growing in:

open cavities: _________ ; confined spaces:__________

large, well-defined shapes ; distorted or skeletal

Molecular bonding & structure

manner of breaking of mineral depends on this

Cleavage

tendency of a mineral to break along specific planes where atomic bonds are weaker; results in smooth, flat surfaces, and the fragments generally retain a similar shape.

Fracture

breaks in an irregular manner, without smooth, flat surfaces.; breakage is random with rough/jagged edges

Luster

appearance of light as it is reflected off its surface; shine

Color

misleading; Many minerals will have a similar appearance, but will have different impurities

Streak

color of the powdered form of the mineral; color can be different from color of mineral

Minerals must be softer than streak plate (white ceramic)

Hardness

How easily a mineral scratches materials

Mohs Hardness Scale

Scale from 1 (softest) to 10 (hardest) •Test by seeing if the mineral can scratch different objects (like human fingernail, copper, penny, glass, steel file)

Hardest mineral: ___________; Softest Mineral: ___________

Diamond; Talc

Why can we only use diamond to scratch diamond

self harm :3

Important minerals to SOCIETY

• Feldspar

• Quartz

• Platinum

• Copper

• Silver

• Gold

Feldspar

• most common

• flat sides/facets

• broken into pieces, it often breaks with one or more flat sides

• One of the most important rocks in granite

Quartz

• many colors; used to make jewelry, glass, electronics & many other industries

• one of most common

• crystals = hexagonal (6)

• hard mineral

• One of the most important rocks in granite

Platinum

• Valuable

• silvery gray with a metallic luster

• jewelry, computers, electronics, and even in our space shuttles and satelites

Copper

• used in wires to conduct electricity

• important in our industries and is also combined with other metals to make brass and bronze

Silver

• another of man's favorite minerals

• similar to gold

• beautiful shiny metal that has many uses

• hard to find

Gold

• another of man's favorite minerals

• similar to gold

• beautiful shiny metal that has many uses

• hard to find