Earth Materials

Objectives Explain the different kinds of bonds and describe their influence on mineral characteristics Define and distinguish between minerals and rocks List key properties used to identify minerals Identify most common mineral families and accessory mineral families Explain what holds rocks together

Elements and Compounds the most fundamental substance into which matter can be separated using chemical means Atom the smallest individual particle that retains the distinct chemical properties of an element Isotopes Atoms with the same atomic number but different mass numbers

Elements and Compounds

Compounds, molecules and bonding A combination of atoms of one or more elements in a specific ratio Molecule The smallest chemical unit that has all properties of a particular compound

Compounds, molecules and bonding The force that holds together the atoms in a chemical compound Ionic bonding Covalent bonding Metallic bonding Van der Waals bonding

Compounds, molecules and bonding Ionic Bonding One atom transfers electron to another, which creates bond Table salt (sodium chloride) Cubic lattice Moderate strength and hardness

Compounds, molecules and bonding Covalent Bond Electrons from different atoms “pair up”, which creates a bond Does NOT produce ions Strongest of chemical bonds

Compounds, molecules and bonding Metallic Bond Electrons shared among several atoms Outer electrons may drift between each other Typically good conductors of electricity

Compounds, molecules and bonding Van der Waals Bond Attraction between electrically neutral molecules with asymmetrical charge Form sheets Considered weak between sheets May feel slippery between sheets

What Is a Mineral? Mineral A naturally formed, solid, inorganic substance with a characteristic crystal structure and a specific chemical composition

What Is a Mineral?

Composition of minerals Crystal structure An arrangement of atoms or molecules into regular geometric lattice. Materials that possess a crystal structure are said to be crystalline

Telling minerals apart Luster The quality and intensity of light reflection Metallic Vitreous Resinous Pearly

Telling minerals apart Hardness A mineral’s resistance to scratching

Telling minerals apart Crystal form Flat or planar surface that forms during the growth of minerals Crystal faces Habit The distinctive shape of a particular mineral Cleavage The manner in which a mineral breaks

Telling minerals apart Color Streak The thin layer of powder made by rubbing a specimen on an unglazed fragment of porcelain Density Reflection of compactness of atoms

Telling minerals apart Other mineral properties translucent, transparent or opaque birefringent magnetic luminescence or fluorescence

Mineral families and their uses Minerals of Earth’s crust Silicate minerals A strongly bonded, complex anion that contains both silicon and oxygen Oxide minerals Contains the simple oxide anion O2-

Mineral families and their uses

Mineral families and their uses

Minerals of Earth’s crust Rock forming minerals Polymerization The formation of a complex molecule by the joining of repeated simpler units Accessory minerals Less common minerals

Minerals of Earth’s crust Other mineral families Carbonate Sulfates Sulfides Phosphates

Mineral resources in modern society Ore deposits A localized concentration that can be extracted profitably. Mining Disturbs Earth’s surface Damage to environment

Rocks: A First Look Rock A naturally formed coherent aggregate of minerals and possibly other non-mineral matter Record history of Earth processes

Rocks: A First Look Igneous Sedimentary Metamorphic Form by cooling and solidification of molten rock Magma Sedimentary Form under conditions of low pressure and low temperature near the surface Metamorphic Altered by exposure to high temperature, high pressure or both.

Rocks: A First Look What holds rocks together? Partly mechanical, partly chemical May be caused by: Compaction Solution Recrystallization

Critical Thinking Which of the following materials are minerals, and why (or why not)? Water, beach sand, diamond, wood, vitamin pill, gold nugget, fishbone Rock samples, taken from the Moon, contain many of the same minerals as those found on Earth. Why might this be the case? Are there valuable ores being mined locally? If so, what are the rocks and minerals of interest?