Bellringer
What happens to the oldest islands in a volcanic
island chain created by a mantle hot spot?
Properties of Magma
Notes
Physical and
Chemical
Properties
• Like other substances, magma is made up of
elements and compounds, and has a certain set
of properties, or traits. Properties can be physical
or chemical.
• An element is a substance that cannot be broken
down into other substances. Carbon, Oxygen,
Argon, Gold, Tin, Lead, etc.
• A compound is a substance made of two or
more elements that have been chemically
combined. Water, Carbon Dioxide, Table Salt,
Sulfuric Acid, etc.
Elements
C
O
H
Compounds
Physical and
Chemical Properties
• Physical properties are traits that can
be observed without changing what a
substance is made of. Examples of
physical properties are hardness, color,
density, melting point, boiling point, and
magnetism.
• Water, under normal pressure, will
always have a melting point of 0°C and
a boiling point of 100°C.
Physical and
Chemical
Properties
• Chemical properties are traits that can be
observed only by changing what a substance is
made of. Examples of chemical properties is a
substances ability to burn and its ability to
combine, or react, to another substance.
•
•
You can often tell if a substance has reacted to
another substance if it changes color, produces
a gas, or forms a new, solid substance
(precipitate).
Iron’s reaction with oxygen to produce rust is an
example of a chemical property.
What is Viscosity?
• Viscosity is a physical property of liquids. How
well a liquid flows depends on its viscosity.
• A liquid with a high viscosity is thick. It flows
very slowly. Honey and syrup have high
viscosities.
• A liquid with low viscosity is thin. It flows very
quickly. Water and Kool-Aid® have low
viscosities.
• The greater the friction between the fluid’s
particles, the higher the viscosity.
http://upload.wikimedia.org/wikipedia/commons/b/b7/Vi
scosity.gif
Video - Three different viscosities
Viscosity of Magma
• Silica is a common substance in Earth’s crust.
Magma contains silica. Magma that contains
more silica has higher viscosity.
• High-silica magma produces high-viscosity
lava. This lava flows slowly.
• High-silica magma cools to form light-colored,
felsic igneous rocks such as granite,
pegmatite, and rhyolite.
Rhyolite
Granite
Pegmatite
Viscosity of Magma
• Low-silica magma produces low-viscosity lava.
This lava flows quickly.
• Low-silica magma cools to form dark-colored,
mafic igneous rocks such as basalt and
gabbro.
Basalt
Gabbro
Viscosity of Magma
•
•
•
Hotter magma has lower viscosity than
cooler magma.
Very hot magma produces lava called
Pāhoehoe. Pāhoehoe has low viscosity. It
flows quickly. It hardens into a rippled
surface.
Cooler magma produces lava called ʻaʻā.
ʻAʻā has high viscosity. It flows slowly. It
hardens into rough chunks.
Pāhoehoe
ʻAʻā
Lava
Type
Pāhoehoe
ʻAʻā
Temperature
HIGH
LOW
Viscosity
LOW
HIGH
Silica
Content
LOW
HIGH
Color
Rock
Examples
DARK
Basalt
Gabbro
LIGHT
Granite
Rhyolite
Pegmatite