Download Mineral:

Jan. 24, 2014
Goal: Identify the properties of minerals
• Pick up notes
DO NOW:
• List the elements found in the following substance:
(use your periodic table if you need help!)
KAl2(AlSi3O10)(OH)2
HOMEWORK:
none
What is a Mineral?
• Minerals make up rocks
• A mineral is a naturally occurring,
inorganic solid that has a crystal
structure & a definite chemical
composition.
– Example: Quartz
• Naturally-occurring = Never man-made
– Ex: Like rocks
• Inorganic = the mineral cannot come from things that
were once living
• “Non Example”: Coal – it is organic because it comes
from plants that lived millions of years ago.
Solid
• The mineral’s atoms are arranged in a
definite pattern. This repeating pattern is
called a crystal.
• Not a liquid or a gas!
CRYSTAL STRUCTURES
Chemical properties
• Chemical properties refer to how the
mineral reacts with an acid.
– Example: Calcite (CaCO3), the main
mineral in limestone and marble,
bubbles when hydrochloric acid is
placed on it.
CaCO3 and HCl
Physical Properties Identify
Minerals
•
Physical Properties include “tests” you can perform
on minerals to determine what type of mineral they
might be. These include:
1.
2.
3.
4.
5.
Streak
Hardness
Luster
Cleavage
Fracture
1. Streak Test
• The color of the mineral’s powder that’s left behind
when it is rubbed across a rough surface
• Example: Pyrite (aka “fool’s gold”) looks like gold,
but its streak looks greenish-black
2. Mohs Hardness Scale
• A scale that ranks 10 minerals from softest to
hardest. You can compare unknown minerals to
the minerals on this scale
• Hardness can be tested by a Scratch Test
– A mineral can scratch any softer mineral
– Mineral can be scratched by any harder mineral
– Minerals that have the SAME hardness can
scratch each other.
3. Luster
• Luster describes how light is
reflected from the mineral’s
surface. What the mineral looks
like.
Types of Luster
– Metallic
– Glassy
– Waxy, Greasy, Pearly
– Dull
– Silky
– Earthy
Ex: Galena
Ex: Topaz
Ex: Talc
Ex: Graphite
Ex: Malachite
Ex: Hematite
4. Cleavage
• One way minerals break
• Easily split along flat surfaces
• Ex: Mica & Halite
5. Fracture
• another way minerals break
• Break unevenly in irregular ways
–Chipped
–Shell-like
–Jagged points
–Crumbles
Ex: Quartz
Ex: Copper & Iron
Ex: Clay
Lead
Quartz
3. Density
 It’s a calculation




(math problem!)
Use a balance to find the mass
Place the mineral in H2O to find the
amount of water it displaces. This
amount is the volume of the mineral.
To find the density, divide mass by
volume
Ex: Sample of Olivine
 Mass = 237 g
Volume = 72 cm3
 Density = 237 g/ 72 cm3 = 3.3
g/cm3
Science Standard
S6E5. How Earth’s surface forms
• b. Minerals make rocks
– EX: Granite may be made of many different
minerals (feldspar, mica, hornblende,
quartz)
• c. Rocks are classified by how they are
formed
– EX: Igneous rocks form from magma/lava
cooling
– d. Different processes change rock & the
surface of the Earth