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

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