Minerals UNIT 2

STANDARDS: STATE OBJECTIVES: NCES 2.1.1, 2.1.3, 2.1.4

LESSON 2

Lesson Objectives By the end of the lesson, you will

have learned: How minerals form Which minerals are the most common

in the crust Which properties are used to identify

minerals Why some minerals are ores and gems

What is a Mineral? Definition of

mineral

A naturally occurring inorganic solid with a specific chemical composition and definite crystalline structure.

Over 3,000 known minerals in the crust

Components of a Mineral Natural Inorganic

crystals

The mineral is formed in nature, not man-made

Inorganic means they are not alive nor have ever been alive

Graphite = yes Sugar = no

Both are crystals, but only graphite is a mineral.

Crystals are solids Specific

composition

Crystals are solids

Table Salt is sodium chloride, NaCl

Definite shape and definite volume

Definite Crystalline Structure Crystal

Basic crystalline systems

A solid in which the atoms are arranged in repeating patterns.

Cubic, Tetragonal, Hexagonal, Orthorhombic

Where do minerals originate?

Minerals can come from cooling magma.

Minerals can form from solution

As the magma cools, beneath the surface, the atoms begin to align in shapes and form crystal structures.

As large volumes of water evaporate, crystals can grow as the solution thickens. (String candy)

Common Elements in the Earth’s Crust

Common Mineral Groups Silicates Oxygen is the most abundant

element in the crust followed by silicon.

Silicates have 1 silicon surrounded by 4 oxygen atoms. From tetrahedron shapes.

Account for 96% of minerals in crust

Common Silicates Quartz

Feldspar

Olivine

Mica

Common Carbonates Carbonate

Limestone (chalk)

Marble

Metal combines with a carbonate ion (CO3)

Common Oxides Oxides

Examples Iron oxide (rust)

Silver oxide (tarnish)

Copper oxide (patina)

Metal ion and Oxygen

Other Mineral Groups Sulfides Sulfates Halides Native Elements

Metal + Sulfur Metal + Sulfate Metal + Halide

(VIIA) Metals themselves

Copper Gold Platinum

Classifying Minerals Minerals are classified according to

their physical and chemical properties.

Identifying Minerals Minerals are

classified by

Color Luster Texture Streak Hardness Cleavage Density Conductivity

Mineral Classification Terms Color

Luster

Texture

The color reflected back when placed in white light

The amount of “shine” Metallic or non-metallic

How it feels Smooth, Rough, Greasy,

Soapy, glassy

Mineral Classification Terms Streak

Hardness

Cleavage

The color left behind as rubbed across unglazed porcelain tile.

How easily the mineral is scratched.

Use the Mohs Hardness Scale Talc (Softest)---Diamond (Hardest)

How the mineral breaks off in planes.

Even cleavage vs jagged breaks

Mineral Classification Terms Density

Conductivity

Radioactive

Ratio of Mass / volume (g/cm3) Specific to minerals

Will it conduct electricity

Does is register when using a Geiger counter

Mineral Uses Common uses

Ores

Gems

Computers, cars, TV, cosmetics, paints, medicine

The substance mined from the earth to extract a metal or mineral.

Valuable minerals prized for their rarity. Emeralds, Rubies, Diamonds

Lesson Review Define a mineral How do minerals form from solutions What are the 2 most abundant elements in

the earth’s crust? Identify 3 major mineral groups Why is color not a good test for a mineral Compare and contrast cleavage and

fracture What is an ore