Transcript Properties of Minerals and Dichotomous Keys

Properties of Minerals
Integrated Science
7 Properties
Crystal Form
 Hardness
 Cleavage and Fracture
 Luster
 Color
 Specific Gravity
 Streak
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2 Properties We Will Not Use
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Crystal Form
◦ Crystal Shapes
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Cleavage and Fracture
◦ Cleavage = breaks into pieces that are the
same shape
◦ Fracture = breaks into random shaped pieces
5 Properties We Will Use
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Hardness
◦ Mohs’ Scale is 1-10
◦ 1 is very soft and 10 is very hard
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Luster
◦ How the light is reflected off the mineral
◦ Types
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Vitreous (Glass-Like)
Metallic
Dull
Pearly
Waxy
Vitreous (Glassy)
Metallic
Dull
Pearly
Waxy
5 Properties We Will Use
Color
 Specific Gravity
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◦ A value greater than 1 means it sinks in water.
( Will feel “heavy.”)
◦ A value less than 1 means it floats in water.
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Streak
◦ Color left by a mineral when streaked on a
porcelain plate.
◦ Not always the same color as the mineral.
Dichotomous Keys
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A dichotomous key is a tool used to
classify or identify certain items.
◦ In the natural world they help to determine
names of trees, wildflowers, mammals, reptiles,
rocks, and fish.
Dichotomous Keys
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Keys consist of a series of choices that
lead the user to the correct name of a
given item.
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"Dichotomous" means "divided into two
parts".
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Therefore, dichotomous keys always give
two choices in each step.
Making A Simple Dichotomous Map
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Think about the important characteristics
that would define these animals!!!
Making A Simple Dichotomous Map
How would we make a Key for
these organisms?
Notice we always are dividing these
into two main characteristics!!!
Dichotomous Keys help identify
things!!!
Can you figure out what these are?