Building a rock…..

Re-building a rock…..

Weathering and Sedimentation
Sedimentary Basic Processes

weathering and

Erosion: The
material

Weathering: The breaking down of Earth materials (i.e.
rocks, soils and minerals) through direct contact with the
atmosphere.
There are two types: mechanical and chemical.


transportation of rock
Sediment Transportation: The movement of solid
particles (sediment), typically due to a combination of the
force of gravity acting on the sediment, and/or the
movement of the fluid in which the sediment is entrained
Sedimentary Basic Processes

Lithification: From the Greek word lithos
meaning 'rock' and the Latin-derived suffix –
ific, is the process in which sediments
compact under pressure, expel connate
fluids, and gradually become solid rock.
 Essentially, lithification is a process of porosity
destruction through compaction and cementation.
 Lithification includes all the processes which
convert
unconsolidated
sediments
into
sedimentary rocks.
Sedimentary Rocks
 Sedimentary: Formed by the settling, deposition and/or
which generally originate
precipitation of Earth materials
from weathered pre-existing rocks
Basic Sedimentary rocks

Clastic sedimentary
rocks
and clasts of loose rock &
• Clastic - broken fragments
mineral debris produced by weathering and erosion.
Grain size decrease
Biochemical Sedimentary
rocks

• Biochemical sedimentary rocks:
• Chemical - precipitation of minerals dissolved in water (lake/sea)
• Biogenic - remains of plants & animals
Dolomite
Limestone
H=3
H=3,5 - 4
Basic ore forming minerals
Luster
Mineral Name
Gray to greenish- Conchoidal
black
fracture
Brassy yellow, high
specific gravity
Metallic
Pyrite
Greenish-black
Conchoidal
fracture
Brassy yellow, high
specific gravity
Metallic
Chalcopyrite
6
Black to dark
gray
Irregular
fracture
Black to gray, high
specific gravity,
magnetic
Metallic
Magnetite
1.5 to 5.5
Red-brown
Irregular
fracture
Steel gray to red, high
specific gravity
Metallic to
dull or earthy
Hematite
5.5 to 6
dark brown
Irregular
fracture
iron black to brownish Metallic
black, high specific
gravity, friable
3.5 to 4
Pale yellow
6 cleavage
planes
Yellow to brown
2.5
Gray
3 cleavage
planes at 90°
Silvery gray, very high Metallic
specific gravity
Streak Color
6 to 6.5
3.5 to 4
Cleavage &
Fracture

Mineral Color,
Specific Gravity etc.
Hardness
Sub-metallic
to resinous
Chromite
Sphalerite
Galena
WHAT YOU NEED TO
KNOW TODAY!

• Identify the difference between clastic and
biochemical sedimentary rocks
• Be able to name and identify the
sedimentary rocks given today, based on
grains, mineralogy and texture
• Be able to name and identify the basic ore
forming minerals given today