Ch. 4: Minerals

Earth’s crust is composed of about 3000 minerals!

Minerals

• Help form rocks

• Shape earth’s surface

• Shape our civilization

• Mineral: naturally occurring inorganic solid with specific chemical composition and definite crystalline structure

Salt vs. Sugar

Crystal• Solid in which atoms are arranged in

repeating patterns

Identifying Minerals

• Color: least reliable

• Luster: the way it reflects light– Metallic, shiny or non-metallic, dull, or pearly..

• Texture: how does it feel? – Smooth, soapy, rough, greasy

• Streak: color of a mineral when it’s broken up and powdered– Very consistent, only useable on softer

minerals

• Hardness: how easily it can be scratched– Friedrich Moh’s scale– Very reliable

• http://geology.com/rocks/

• Density– How tightly compacted

a substance’s molecules are

D = m/v– Less dense than liquid:

floats– More dense than

liquid: sinks

Special properties

• Calcite bends light, gives a double image

• Magnetite: a natural magnet

Mineral uses

• Ore: a mineral is an ore if it…– contains a useful substance

AND– can be mined for a profit

Gem – valuable mineral prized for beauty and rarity

Find the answers in ch. 4

• What mineral forms rubies and sapphires? What’s the difference between them?

• Which is more valuable – a diamond or emerald? Why?

• Matter: anything that has volume and mass– Made of elements

• Elements: substance that connot be broken down into smaller substances by physical or chemical means– Purely and completely ______________

Elements

• 92 naturally occuring elements on earth or in stars

• Hydrogen and Helium are the most abundant elements in the universe!

• Why?

Elements that are also minerals:

• Copper• Silver• Sulfur

• Most minerals are compounds

In Earth’s crust…

• Silicon and oxygen are the most abundant

In the atmosphere:

• 78% nitrogen• 21% oxygen• 1% ozone, water

vapor

In the oceans:

What do you think?

• Sodium

• Chloride

• Hydrogen

• Oxygen

• Why?

• 97% of all water on earth is salt water!

Back to Earth’s crust…

• Continental crust: granite

• Oceanic crust: basalt– More dense