What are minerals and ores? How is soil formed, layers of soil, types of soil

2. MINERALS
- Is a substance that has formed from one or
more elements in the earth.
- Rocks are formed from different minerals stuck
together.
- Example: Granite rock
(mixture of feldspar,
quartz and mica)
r r

3. - Gold, silver and copper are
examples of minerals found on
their own.
- Most other minerals are
compounds.
Gold
Silver
Copper

4. - The atoms of elements in a
mineral usually join together to
form a crystal structure.
- Example: Silicon and oxygen
form a crystal substance called
quartz.

5. - Each mineral can be recognised by:
a) Shape
b) Colour
c) Luster
d) Hardness
e) Streak colour (when rubbed against a white rough
porcelain surface)

6. - Some rare minerals have attractive properties
(shiny surface, pleasing colour and sparkle)
- These minerals are called gemstones.
- Example: Opal, diamond and beryl
Opal Diamond
Beryl

7. ORES
• DURING THE FORMATION OF SOME ROCKS
(SEDIMENTARY ROCKS) METAL ELEMENTS GATHER
IN LARGE QUANTITIES.
• ROCKS THAT POSSESS LARGE QUANTITIES OF
METAL COMPOUNDS ARE CALLED ORES.
• BAUXITE IS AN ORE RICH IN ALUMINIUM.
• HAEMATITE IS AN ORE RICH IN IRON.
• ORES ARE MINED AND THEN PROCESSED, USUALLY
USING HEAT.

8. SOIL
• SOIL IS USUALLY COVERED WITH PLANTS THAT
GROW IN IT.
• SOIL HELPS PLANTS TO SET DOWN THEIR ROOTS
AND HOLD THEIR POSITION IN A HABITAT.
• SOIL ALSO STORES WATER AND MINERALS FOR
PLANTS TO USE AS THEY GROW.
• SUCCESSFUL FARMING DEPENDS ON SOIL SO
OVER THE YEARS SCIENTIST HAVE STUDIED
SOIL.

9. HOW SOIL FORMS.
- The main part of soil is made from small
particles or fragments of rock.
- The process by which rock breaks down to form
fragments is called weathering.

10. Types of weathering
Physical
weathering
Chemical
weathering
• CHANGES IN
TEMPERATURE
• EFFECT
OF ICE
• ABRASION • EFFECT OF
PLANTS
• RAIN
WATER
• HOT AND WET
WEATHER
CONDITIONS

11. PHYSICAL WEATHERING
CHANGES IN TEMPERATURE
• WHEN ROCKS HEAT UP THE MINERALS EXPAND BY
DIFFERENT AMOUNTS, SO THEY PUSH ON EACH
OTHER.
• WHEN THEY COOL DOWN THEY CONTRACT AND
SPACES DEVELOP BETWEEN THEM.
• AFTER BEING HEATED AND COOLED MANY TIMES
THEY BECOME LOOSE AND FALL AWAY.
• IN THE SAHARA DESERT TEMP. DURING THE DAY IS
ABOVE 40 ⁰C AND DURING NIGHT IT IS BELOW
-7 ⁰C SO THE ROCKS CRUMBLE.
EFFECT OF ICE
• WHEN IT RAINS ON POROUS ROCK LIKE
SANDSTONE THE WATER CAN STAY IN THE ROCK
FOR SOME TIME.
• WHEN THE WATER IN THE ROCK FREEZES IT
EXPANDS.
• ICE PUSHES ON THE SIDES OF THE PORES AND
MAKES THE ROCK CRUMBLE.
• WATER MAY COLLECT IN CRACKS AND FREEZE,
PUSHING AGAINST THE SIDES AND MAKING ROCKS
BREAK.

12. ABRASION
• OCCURS WHEN PIECES OF ROCK RUB TOGETHER.
• EXAMPLES: WHEN PEBBLES ARE CARRIED IN A
FAST FLOWING RIVER.
• GLACIERS MOVING SLOWLY DOWN MOUNTAINS
RUB ON THE ROCKS IN THE VALLEY FLOOR AND
SIDES AND WEAR THEM DOWN
• SAND GRAINS BLOWN IN THE WIND
(SANDSTORM) RUB ON ROCK SURFACES AND
WEAR THEM DOWN.
• HIGH TIDE THROWS PEBBLES ON BEACHES
EFFECT OF PLANTS
• IF THE SEED OF A TREE OR BUSH SETTLES IN A
CRACK AND GERMINATES THE ROOT CAN GROW
IN THE SOIL (SETTLED INSIDE THE CRACK).
• TREES AND BUSHES HAVE STRONG, WOODY
ROOTS THAT GROW LARGER EVERY YEAR, SO
THEY PUSH ON ITS SIDES AND BREAK UP THE
ROCK.

13. CHEMICAL WEATHERING
RAIN WATER
• ACID IN RAINWATER FALLING ON ROCKS SUCH
AS GRANITE CAN BREAK IT UP INTO SMALLER
PIECES.
HOT AND WET WEATHER CONDITION
• HOT, WET WEATHER CONDITIONS SPEED UP
CHEMICAL REACTIONS MORE QUICKLY THAN
DRY, COLD CLIMATES
• WHEN TINY ROCKS AND SAND CARRIED BY
WIND AND WATER SETTLE DOWN IT FORMS
SOIL.

14. LAYERS OF SOIL
Topsoil
Subsoil
Bedrock
Has lots of Humus. Many
small animals live in it.
Does not have lots of Humus,
but it has small pieces of rock
It has no Humus. Made up of
solid rock.

15. SOIL IS A MIXTURE OF
MANY THINGS.
Water Air
Tiny
pieces
of
rock
Humu
s

16. PART OF SOIL
THAT IS MADE UP
OF PARTS OF
HUMUS

17. TYPES OF SOIL
- Soil can have
different colors.
- Soil can have
different sizes of
rocks (grains)

18. Clay soilSilt soilSand soil
Types of soil
Properties
Size of
particles
StickySmoothGritty (coarse)
Texture
(Feel when
wet)
Not much air
space
Some air spaceLots of air spaceAir space
Does not pass
(Stays wet)
Stays a while
Passes fast
(Dry fast)
Water

20. - Loam is a type of soil made of 40%
sand, 40% silt and 20% clay.
- It contains large amount of humus.
- It is the most suitable for cultivation.