Rocks and Minerals

Question 1

Outline the layers of the Earth and their composition. Include a diagram.

Answer 1

Crust: The outermost layer, made of solid rock.

Mantle: The thick layer beneath the crust, composed of semi-solid rock that flows slowly over time. It is made up of silicate minerals rich in magnesium and iron. takes up 85% of earth

Core: The innermost layer, consisting of a liquid outer core made of iron and nickel and a solid inner core also composed of iron and nickel.

     --------------------------
    |       Crust             |  
     --------------------------
    |       Mantle            |
     --------------------------
    |       Outer Core        |
     --------------------------
    |       Inner Core        |
     --------------------------

Question 2

Explain the difference between magma and lava.

Answer 2

Magma is molten rock beneath the Earth’s surface. It is found in the mantle and can be stored in magma chambers.
Lava is magma that has reached the Earth’s surface through a volcano or a fissure. Once it erupts, it is called lava.

Question 3

Define igneous rocks.

Answer 3

Igneous rocks are formed from the cooling and solidification of molten rock (magma or lava). The rate at which magma or lava cools affects the texture and appearance of the rock.

Question 4

What is the difference between intrusive and extrusive igneous rocks?

Answer 4

Intrusive igneous rocks form when magma cools slowly beneath the Earth’s surface, resulting in large crystals (e.g., granite).
Extrusive igneous rocks form when lava cools quickly on the surface, resulting in small crystals or a glassy texture (e.g., basalt, pumice).

Question 5

What are crystals?

Answer 5

Crystals are solid, geometric forms of minerals with a repeating pattern of atoms. They form when a substance cools and the particles arrange in a regular, repeating pattern.

Question 6

What are minerals?

Answer 6

substances naturally formed in the Earth.
Minerals are naturally occurring, inorganic solids with a specific chemical composition and a crystalline structure. They are the building blocks of rocks.

Question 7

List the characteristics of igneous rocks.

Answer 7

Formed from cooled and solidified molten rock (magma or lava).
Typically hard and durable.
May contain crystals or be fine-grained, depending on the cooling rate.
Commonly have a granular texture.

Question 8

Write the names and features of some extrusive igneous rocks.

Answer 8

Basalt: Fine-grained, dark-colored, and rich in iron and magnesium. It is commonly found in oceanic crust.
Pumice: Light-colored, porous, and contains gas bubbles. It is often used in scrubbing and cleaning products.
Obsidian: A natural glass with a smooth, shiny texture and dark color.

Question 9

Write the names and features of some intrusive igneous rocks.

Answer 9

Granite: Coarse-grained with visible crystals of quartz, feldspar, and mica. It is commonly used in construction.
Diorite: Coarse-grained with a mix of light and dark minerals, found in continental crust.
Gabbro: Coarse-grained, dark-colored rock rich in iron and magnesium.

Question 10

List 3 igneous rocks and their uses.

Answer 10

Granite: Used for countertops, buildings, and monuments.
Basalt: Used in road construction and as aggregate in concrete.
Pumice: Used in abrasives, such as pumice stones, for cleaning and exfoliation.

Question 11

Define weathering.

Answer 11

Weathering is the process by which rocks break down into smaller particles due to physical, chemical, or biological forces.

Question 12

List and explain the different types of physical weathering.

Answer 12

Mechanical weathering: Breaks rocks into smaller pieces without changing their composition. Examples include freeze-thaw, thermal expansion, and abrasion.

Freeze-thaw weathering: Water enters cracks in rocks, and when it freezes, it expands, breaking the rock apart.

Exfoliation: The peeling away of layers from rock surfaces due to temperature changes.

Abrasion: Rocks rubbing against each other, causing them to wear down

Question 13

Define chemical weathering.

Answer 13

Chemical weathering occurs when rocks undergo chemical reactions that break down the minerals within them. This often happens with the presence of water, air, or acidic conditions.

Question 14

List some of the causes of chemical weathering.

Answer 14

Water: Dissolves minerals, causing them to break down.

Acids: Acid rain or organic acids can dissolve rock minerals.

Oxygen: Oxidation, like rusting of iron, is a form of chemical weathering.

Question 15

*Define erosion.

Answer 15

Erosion is the process by which rocks and soil are worn and moving broken down materials to a new location.

Question 16

*Explain what deposition/ sedimentation is.

Answer 16

Deposition is the process where sediments (like sand, silt, or clay) settle and accumulate in a new location, forming layers. This often occurs in bodies of water, where particles slowly settle due to gravity.

Question 17

*Explain what sedimentary rocks are and how they form.

Answer 17

Sedimentary rocks form from the accumulation and compression of sediments (such as sand, clay, or organic material) over time. These rocks often have layers (strata) and can contain fossils.

Question 18

*What are clastic sedimentary rocks and give some examples.

Answer 18

Clastic sedimentary rocks are made from fragments of other rocks. Examples include:

Sandstone: Formed from sand-sized particles.

Shale: Formed from fine clay particles.

Conglomerate: Made of rounded gravel-sized fragments.

Question 19

*What are chemical sedimentary rocks and give some examples.

Answer 19

Chemical sedimentary rocks form when minerals precipitate from water, often due to evaporation, like limestone, rock salt, and gypsum

Question 20

What are organic sedimentary rocks and give some examples.
.

Answer 20

Organic sedimentary rocks are made from the remains of living organisms. Examples include:

Coal: Formed from plant material.

Chalk: Composed of microscopic marine organisms’ shells (calcium carbonate)

Question 21

What are fossils and how do they form?

Answer 21

Fossils are the preserved remains or traces of ancient organisms. They form when plants or animals are buried quickly by sediments, and over time, minerals replace the organic material, turning it into rock.

Question 22

Explain what strata are and what they can tell us.

Answer 22

Strata are layers of sedimentary rock. Each layer can represent a different period of deposition, and by studying strata, we can learn about the Earth’s history, including past climates and the types of organisms that lived at different times.

Question 23

Explain what metamorphic rocks are and how they form.

Answer 23

Metamorphic rocks are formed when existing rocks (either igneous, sedimentary, or other metamorphic rocks) are subjected to high pressure, heat, or chemically active fluids, leading to changes in their mineral composition and texture.

Question 24

What is the difference between regional and contact metamorphism?

Answer 24

Regional metamorphism occurs over large areas under high pressure and temperature, usually caused by tectonic forces.
Contact metamorphism occurs when rocks are heated by nearby molten magma or lava, but without the high pressure.

Question 25

Name some of the most common examples of metamorphic rocks.

Answer 25

Slate: Formed from shale under low-grade metamorphism.
Marble: Formed from limestone under high-grade metamorphism.
Schist: Formed from shale or other rocks with visible crystals.

Question 26

*Draw the rock cycle.

Question 27

Name some of the common minerals.

Answer 27

Quartz
Feldspar
Mica
Calcite
Halite

Question 28

Outline the main properties of minerals.

Answer 28

Hardness (resistance to scratching)
Color
Luster (how the mineral reflects light)
Cleavage/Fracture (how a mineral breaks)
Density
Streak (the color of the mineral’s powder)

Question 29

What are the 4 main steps involved in mineral exploration?

Answer 29

Surveying: Identifying potential areas for mineral deposits.
Sampling: Collecting samples from the site for testing.
Analysis: Testing samples to determine the presence of valuable minerals.
Drilling and Evaluation: Using drilling techniques to obtain deeper samples and evaluate the economic viability of the mineral deposit, including assessing the cost-effectiveness of extraction.