Minerals: What are They? Composition and Formation Section 5.1 and 5.2 Minerals Minerals: What are They? Composition and Formation

Minerals are essential: They are every manufactured product. They’re essential to good health (vitamins and minerals). Knowledge of minerals enables us to understand Earth’s processes.

What is a mineral? Five characteristics that make a substance a mineral: _____________________ Occurs naturally Solid Definite chemical formula Orderly (crystal) arrangement of atoms Inorganic (never alive)

Top 8 elements in the Earth’s crust: Silicates #1 #2 ______________________ #3 ______________________ #4 ______________________ #5 ______________________ #6 ______________________ #7 ______________________ #8 ______________________ Oxygen 46.6%_ Silicon 27.7% Aluminum 8.1% Iron 5.0% Calcium Sodium Potassium Magnesium

Most minerals are … Compounds? Elements? Mixtures? Examples: Salt (NaCl) calcite (CaCO3) Sand (SO2)

Native minerals are composed of just one, single element. Examples: 1. ____________________ 2. ____________________ 3._____________________ Gold Copper Diamond * * Is diamond an element on the Periodic Table??

A group of one or more minerals The Rock What is a ROCK by definition? A group of one or more minerals bound together in varying quantities

Except….. Limestone, which is made of only ONE mineral: calcite.

How Minerals Form page 97 Magma Pressure Process Evaporation Process (Precipitation) (most)

How Minerals form (pg.97) The Magma Process: Molten (liquid) rock in a magma chamber at, near, or under earth’s surface, rises 2. The magma begins to cool and atoms, ions and molecules form various mineral compounds. 3. The molecules of the compounds mass together to form crystals.

The Pressure Process: 1. Rock is exposed to high pressures and temperatures, and the minerals begin to break down. 2. As pressure and temperature continue, the molecules RE-FORM into new minerals. 3. The minerals are elongated in shape due to the pressure.

The Evaporation Process: 1. Ions (such as salt or calcium) are dissolved in water. 2. The water evaporates, and the ions form minerals such as halite and calcite. Examples: halite (NaCl salt) limestone (calcite)

The kind of mineral that is formed depends on… 1. Which elements are present when it forms 2. The amount of an each element present. * The same magma chamber can form different minerals.

Time Space Temperature Pressure Concentration crystal = regular, orderly arrangement of atoms Factors that determine crystal formation: Time Space Temperature Pressure Concentration Largest uncut diamond found in the Letseng Mine in southern Africa. A near-flawless white gem weighing nearly 500 carats. It was discovered on Sept. 8, 2008 It weighs 478 carats, with very few inclusions and of outstanding color and clarity.

1. TIME and mineral formation The RATE at which the molten magma cools determines the crystal size.

be LARGE and well-formed If the magma cools s-l-o-w-l-y then the crystals will…. * (example: granite) be LARGE and well-formed #44

If the magma cools quickly, then the crystals will…. *example: obsidian cools instantly so it has no crystal structure, but a glass-like structure be Small / microscopic / not well-formed

Classzone Internet Investigation ES0506 “How Do Crystals Grow?” 2. Space 3. Temperature 4. Pressure http://www.classzone.com/books/earth_science/terc/content/investigations/es0506/ Answer #1-8 on a separate sheet of paper!