Download Ch. 4: Minerals

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