NOTES: Rocks and Minerals (Eureka p. 302- 307)
The Lithosphere
1-The lithosphere is a rigid structure that is made up of the Earth’s crust and part of the upper mantle.
2-The lithosphere is between 70 km and 150 km thick.
3-It contains minerals the plants need
4-It contains several important natural resources.
Minerals Vs Rocks
5-A mineral is a homogeneous (pure) natural (not man-made) and non-living substance.
6-A rock is aheterogenous blend of differently sized grain of different kinds.
7-There are three kinds of rocks that are categorized by the way they are formed.
Three Types of Rocks
8-Igneous rock results _from cooling and solidification of magma.______
9-Sedimentary rock derives from fragments of rock called sediment that are subject to erosion and may also contain fossils
10- Metamorphic rock has has undergone a transformation caused by heat and pressure,
Igneous Rock
There are three types of igneous rock:
11-Intrusive (or Plutonic)
- Slow cooling of magma within the Earth’s crust
•Has large crystals
•Example: Gabbro
12-Extrusive (or volcanic)
•Formed when lava cools in contact with air or water
•Has microscopic crystals
•Example: Obsidian
13-Porphyritic
•Undergoes two cooling phases
•Crystals vary in size
•Example: Certain types of Granite
Sedimentary Rock
14-Composed of pieces of rock from the crust that have broken away, are carried and polished by water, wind and landslides._
15-These pieces or sediments are then deposited in layers, compacted and cemented over time.
Example: Limestone
16-Fossils
–An imprint or remnant of an animal or plant preserved in the Earth’s crust.
–Fossils are sometimes found in sedimentary rock.
Metamorphic Rock
17-Rocks (igneous, sedimentary or even existing metamorphic) transformed by the action of pressure and heat
18-The transformation results in minerals aligning in sheets or bands
Example: Marble
SixObservations or Tests we Do to Identify a Rock or a Mineral:
19-
•1-Density
•2- Grain Size:
Coarse (use naked eye or magnifying glass) or fine (need a microscope)
•3- Hardness:
"hard" rock scratches glass and steel, usually signifying the minerals quartz or feldspar (Mohs hardness 6-7 and up);
"soft" rock does not scratch a steel knife but scratches fingernails (Mohs 3-5.5);
"very soft" rock does not scratch fingernails (Mohs 1-2). Igneous rocks are always hard.
•4- Magnetism :
•5- Lustre: shiny or dull
•6- Colour streak :
Most tests that are done on minerals are non-characteristic properties.
However, when they are combined, they often enable us to identify rocks and minerals.
Fill the following table in using pg 307 of the Eureka Textbook:
Igneous Rock / Sedimentary Rock / Metamorphic RockHow are they formed? / Cooling and solidification of magma / Erosion and transportation of fragments that are then deposited, compacted and cemented / From already formed rocks that change under pressure and heat
What are they made of? / From minerals (such as feldspar and quartz) / From mineral grains, inorganic debris and fossils / From various minerals
How are their components distributed? / The grains are often disrupted / Sequence of layers corresponding to layers of accumulated sediments / Light/ dark bands (gneiss)
Rigid sheets
(mica shiste or slate)
The Rock Cycle