Transcript Mafic, fine grained, extrusive

IGNEOUS ROCKS
Igneous – derived from the Latin
word ignis, meaning Fire.
IGNEOUS ROCKS
Lava is molten rock found at or near
Earth’s surface.
Magma is molten rock found beneath
Earth’s surface.
Igneous Rocks form from both lava and
magma.
3 Ways Magma Can Form
• Pressure – The high pressure inside Earth causes Hot
rocks and minerals to remain solid. When those hot
rocks rise and the pressure lowers, the minerals
melt.
• Temperature – High temperatures melt minerals.
Each mineral has a different melting point – so some
minerals melt when others remain solid.
• Composition – If fluids, such as water, combine with
the rock, the composition of the rock changes which
lowers the melting point enough for it to melt and
lower temperatures.
Igneous Rock
• Forms when hot, liquid
rock or magma, cools and
solidifies
• Found near volcanic
activity
• Liquid magma is a mixture
of many minerals
Intrusive & Extrusive
Those igneous rocks that form from magma are
referred to as INTRUSIVE.
INTRUSIVE = Inside
Those igneous rocks that form from lava are
referred to as EXTRUSIVE.
EXTRUSIVE = Outside
Extrusive
Intrusive
Magma
TEXTURE of Igneous Rocks
• Determined by how fast the
magma cools
• Smooth grained rocks are
formed by magma that cools
quickly (Extrusive)
• Coarse grained rocks are
formed when magma cools
slowly (Intrusive)
IGNEOUS ROCK FORMATIONS
Intrusive
Extrusive
• Form Below Earth’s
surface and inside the
Earth
• Forms on the Earth’s
surface
• Intrusive rocks have a
coarse grained texture
because ?
• Extrusive rocks have a
smooth texture
because ?
COMPOSTITION of Igneous Rocks
• Light colored rocks are less dense and rich
in Quartz Felsic
(aluminum, potassium, silicon and sodium)
• Dark colored rocks are more dense and
contain Plant Nutrients.
(calcium, iron, magnesium)
Mafic
Igneous Rock QUESTION
Obsidian is a dark-colored volcanic glass that forms from the very rapid
cooling of molten rock material. It cools so rapidly that crystals do not form.
• Is this rock Felsic or
Mafic?
• Is it fine-grained or
coarse-grained?
• Is this rock Intrusive or
Extrusive?
Mafic, fine grained, extrusive
Andesite – Fine-grained, extrusive Felsic igneous rock
Basalt is also an
abundant rock on the
Moon. Much of the
Moon's surface is
underlain by basaltic lava
flows and flood basalts.
These areas of the Moon
are known as "lunar
maria."
Basalt – Fine-grained, extrusive Mafic
Diorite – Coarse-grained, intrusive. Mixture of Mafic and Felsic
Gabbro – Coarse-Grained, intrusive, Mafic igneous rock
Pumice – Extremely Fine-Grained, Extrusive Felsic Igneous Rock
Form during explosive volcanic eruptions from the cooling of the frothy magma
Forms when some volcanoes
erupt, a rush of gas blows out of
the vent. This gas was once
dissolved in the magma below.
The gas often blows out small
bodies of magma that solidify as
they fly through the air.
Scoria – Extremely fine-grained, Extrusive Mafic
Igneous Rock