Download Properties of Rocks-Lesson 1

Properties of Rocks
Lesson 1
What you will learn today
• What the words homogeneous and
heterogeneous mean
• What makes a rock a rock
Homogeneous minerals
• They have a unique crystalline
structure and specific hardness-just
like this close-up of sandstone
See the
crystals?
What does Heterogeneous
Mean?
• Rocks are a made up of more than
one mineral.
Quartz
+
Mica
+
Feldspar
=
Granite
Properties of Rocks
There are five properties which help
identify rocks:
Streak
Hardness
Luster
Color
Density
Hardness
200 years ago Friedrich Mohs
devised a scale by which the
hardness of minerals could be
ranked from 1 to 10.
ROCK JOKE
What is a rock’s favorite transportation?
A rocket!
At the high end (10) Mohs put the
hardest mineral, the diamond
At the low end (1) Mohs put talc
which is the softest mineral
How To Test Hardness
• The hardness of a mineral can be
tested by doing a scratch test
• Many minerals do not go higher
than 7 or 8
Hardness Scale
• If your fingernail easily scratches the
mineral, it is a 1
If glass can scratch the mineral, it
is a 5
If quartz can scratch the mineral
it is a 7
Luster
Describes the appearance of the mineral’s
surface
Is it dull?
Is it shiny?
Is it glassy?
Is it waxy?
Describes characteristics of color
and color combinations
Streak
Streak describes the color left by the
rock when drawn across hard
surface
This type of test helps when trying
to identify dark looking minerals.
Density
Describes the weight of the rock.
Gold has a density of 19
Talc has a density of 2.7
The density of water is 1
What does homogeneous mean?
What does heterogeneous mean?
What are the 5 properties of a rock?
Thanks goes to:
Sues’ Gemstones for the diamond
pictures
Intel for creating a microscope that
hooks into the computer for the close
up pictures