How are rocks different
from minerals?
Definition of Mineral:
1. Naturally occurring
2. Solid substance
3. Orderly crystalline structure
4. Definite chemical composition
5. Inorganic
Rocks Tell Stories
Records of Geologic Past
Rock Classification – 3 major
groups based on their methods of
formation or origin
1. Igneous rocks … from cooling and
solidification of lava or magma
2. Sedimentary rocks … from compacted
and cemented sediments, or chemical
precipitates or evaporites
3. Metamorphic rocks …
meta (change) morphic (form) … rocks
changed by heat and pressure –but
remain solid
ESRT – Page 6
Igneous- rocks that form when molten
magma solidifies.
Lava-magma that reaches the Earth’s
surface.
Magma-liquid rock deep within the Earth.
• Intrusive- igneous rocks which form
when magma solidifies deep
underground.(plutonic)
• Extrusive- igneous rocks which form
when lava cools rapidly at Earth’s
surface. (volcanic)
Felsic-lava that is rich in silica, light in
color and low density.
MAFIC
FELSIC
Mafic-lava that is rich in iron &
magnesium, dark in color, & high density
Texture-the size of the mineral
grains or crystals. (glassy, fine,
course)
Porphyry- a rock that contains a
mixture of various sized crystals.
Igneous Rocks
IGNEOUS ROCKS
Types of Igneous Rock
Where & How they cool
Type of Texture
IGNEOUS ROCKS
Type of Igneous Rock
Intrusive
Extrusive
Where & how they cool
Magma cools
slowly inside
the earth
Lava cools rapidly
at the
Earth’s surface
Type of Texture
coarse
Very coarse
Non-Vesicular
Glassy
Vesicular/Non
Fine
Sedimentary Rock Vocabulary
•Clastic – rocks made up of fragments of other rocks.
•Bioclastic- rock formed from the remains of living
organisms.
•Lithification- the process of forming a rock.
•Cementation- the process of sediments being
stuck together by minerals in running water.
•Compaction-process in which air and water are
squeezed out of sediments, forming a sed. rock.
•Precipitation (from solution)- when water evaporates
and leaves behind the minerals that were dissolved
in the water.
Sedimentary Rocks
TYPES OF
How they formed (method of lithification)
Grain Sizes
Hints/Clues to look for
Sedimentary
Bioclastic
(Organic)
Clastic
Crystalline
(Chemical)
How Formed (method of Lithification)
Fragments of rocks
and organic material
compacted & cemented
together
Fragments
of rocks compacted
and cemented together
Grain Sizes
Pebbles, cobbles,
Boulders (mixed)
Hints/Clues to look for
fossils of
plants or animals
sand
silt
clay
Minerals are dissolved into
water, then the water
evaporates and leaves the
minerals behind
Large crystal
Metamorphic Rock Vocabulary
• Recrystallization- the repeated process of melting and
solidifying magma into crystals.
• Foliation- a metamorphic rock with visible parallel
bands of minerals.
• Regional metamorphism- metamorphism that affects
rocks over large areas at tectonic plate boundaries.
(heat & pressure)
• Contact metamorphism-metamorphism of a rock due
to the extreme heat of contact with magma.
METAMORPHIC ROCKS
Type of Metamorphism
Type of Texture
Grain Size
METAMORPHIC ROCKS
Type of Metamorphism
Regional
Metamorphism
Contact
Metamorphism
Occurs over a very large area (thousands
of Km’s) during tectonic activity. The
movement of tectonic plates creates
tremendous heat and pressure at plate
boundaries causing the rocks to change
Hot magma pushes through
existing rock. The heat from the
magma can change the structure
and composition of the
existing rock.
Type of Texture
Foliated
Fine
Grain Size
Fine
MEDIUM Coarse
Nonfoliated
Medium
Coarse