Geology Lesson 4.1: Rock-Forming Minerals

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Questions and Answers

What is the primary cause of contact metamorphism?

Chemical reactions in the water

Heat from nearby magma (correct)

Cooling of igneous rocks

Pressure from surrounding rocks

Which type of metamorphism occurs due to pressure building up deep within the Earth?

Hydrothermal metamorphism

Contact metamorphism

Dynamic metamorphism

Regional metamorphism (correct)

Which of the following is a characteristic of foliated metamorphic rocks?

They contain aligned grains of flat minerals (correct)

They have a granular texture

They originate from sedimentary rocks

They do not change composition

What is the primary mineral composition of marble?

Calcium carbonate Signup and view all the answers

Which of the following rocks is classified as non-foliated?

Quartzite Signup and view all the answers

Which property of a mineral describes its resistance to scratching?

Hardness Signup and view all the answers

What does the term 'streak' refer to when identifying minerals?

The powdered color of the mineral Signup and view all the answers

In mineralogy, 'cleavage' refers to a mineral's ability to:

Break along flat surfaces Signup and view all the answers

What is the term for the shape in which a mineral grows, reflecting its internal structure?

Crystal habit Signup and view all the answers

Which of the following mineral groups is primarily composed of a metal joined by sulfur?

Sulfides Signup and view all the answers

What does the specific gravity of a mineral measure?

The mineral's weight compared to water Signup and view all the answers

Which of the following mineral groups is characterized by the presence of chlorine, fluorine, bromine, and iodine?

Halides Signup and view all the answers

The melting point of a mineral refers to:

The temperature at which it turns from solid to liquid Signup and view all the answers

What is the general composition of pyroxene minerals?

XY(Al,Si)2O6 Signup and view all the answers

Which characteristic is NOT a physical property used for mineral identification?

Solubility Signup and view all the answers

What does high specific gravity indicate about a mineral?

It contains heavy elements. Signup and view all the answers

Which of the following statements is false regarding minerals?

Talc can scratch diamond. Signup and view all the answers

In what way do intrusive igneous rocks differ from extrusive igneous rocks?

They have larger mineral crystals. Signup and view all the answers

What would you expect the temperature of magma to be?

Between 700 °C and 1,250 °C Signup and view all the answers

Which of the following elements is NOT typically associated with felsic rocks?

Calcium Signup and view all the answers

What defines a rock in geological terms?

A naturally occurring solid mixture. Signup and view all the answers

Which mineral is classified under the oxides and hydroxides group?

Hematite Signup and view all the answers

What is the chemical structure of quartz?

SiO2 Signup and view all the answers

Which type of minerals are characterized by being brightly colored and brittle?

Chromates Signup and view all the answers

Which of the following methods involves dissolving a mineral in acid for analysis?

Wet chemical analysis Signup and view all the answers

What does the chemical structure XAlSi3O8 represent?

Feldspar Signup and view all the answers

Mica is primarily characterized by its:

Hardness and perfect cleavage Signup and view all the answers

Which mineral group includes apatite?

Phosphates, arsenates, vanadates Signup and view all the answers

What mineral under the silicates group is known for its glass-like quality?

Quartz Signup and view all the answers

Which type of igneous rock is formed from rapid cooling of molten rock material?

Obsidian Signup and view all the answers

What is the primary characteristic of sedimentary rocks compared to igneous rocks?

Formed from weathering and erosion Signup and view all the answers

Which sedimentary rock is primarily composed of calcium carbonate?

Limestone Signup and view all the answers

What type of metamorphic process occurs under extreme temperature and pressure?

Solid state changes in existing rocks Signup and view all the answers

Which of the following is NOT a type of sedimentary rock?

Mafic Signup and view all the answers

Which characteristic best defines the formation of coal?

Accumulation of plant materials in swamp environments Signup and view all the answers

How are sediments arranged in sedimentary rocks?

In layers with older ones at the bottom Signup and view all the answers

What distinguishes intrusive igneous rocks from extrusive igneous rocks?

Extrusive rocks are formed from lava cooling quickly at the surface Signup and view all the answers

Study Notes

Rock-Forming Minerals

Minerals are naturally occurring, inorganic solids with a definite chemical composition and ordered crystal structure.
Common physical properties for mineral identification include color, streak, luster, crystal habit, cleavage, fracture, hardness, and specific gravity.
Chemical properties of minerals include solubility and melting point.

Mineral Groups Based on Chemical Composition

Elements: Composed of one element (e.g., copper, gold, silver).
Sulfides: Contain a metal combined with sulfur (e.g., cinnabar, pyrite).
Halides: Nonmetals with chlorine, fluorine, bromine, or iodine (e.g., fluorite, halite).
Oxides and Hydroxides: Composed of metals joined with oxygen, water, or hydroxyl (e.g., cuprite, hematite).
Nitrates, Carbonates, Borates: Composed of metals combined with carbon, nitrogen, or boron (e.g., malachite, borax).
Sulfates: Contain one or more metals with a sulfate compound (e.g., anhydrite).
Chromates, Molybdates, Tungstates: Formulas often involve bright colors and brittleness (e.g., wulfenite).
Phosphates, Arsenates, Vanadates: Contain phosphates or similar groups (e.g., apatite).
Silicates: Largest mineral group, have varying amounts of silicon and oxygen (e.g., dioptase, labradorite).

Analysis of Minerals

Wet chemical analysis involves dissolving the mineral in acid for further study.
Spectroscopic techniques analyze mineral composition based on light absorbance.

Types of Rocks

Rocks are naturally occurring solid mixtures of minerals or organic matter.
Classified by formation, composition, and texture, and undergo change through the rock cycle.

Igneous Rocks

Formed from cooled magma, magma originates from heat, pressure, or compositional changes.
Cooling temperature ranges from 700 °C to 1,250 °C.
Felsic: Light-colored, rich in aluminum and silicon.
Mafic: Dark-colored, rich in iron and magnesium.
Intrusive Igneous Rocks: Coarse grain due to slow cooling (e.g., granite).
Extrusive Igneous Rocks: Fine grain due to rapid cooling (e.g., basalt, obsidian).

Sedimentary Rocks

Formed from weathering and erosion; sediments layer over time and become compacted and cemented.
Classified into clastic (fragmented rock), chemical (minerals crystallizing from solution), and organic (remains of living organisms).
Example: Limestone formed primarily from calcium carbonate.

Metamorphic Rocks

Formed by changes in existing rocks under temperature and pressure without melting.
Contact Metamorphism: Changes due to nearby magma heating.
Regional Metamorphism: Changes due to intense pressure from tectonic activity.
Foliated: Bands of aligned minerals (e.g., gneiss).
Non-Foliated: No banding present (e.g., marble).

The Rock Cycle

Illustrates how rocks transform from one type to another over geological time.

Mining Debate

Focuses on the pros and cons of mining practices and their impact on the environment.

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Description

This quiz focuses on identifying common rock-forming minerals and understanding their physical and chemical properties. By the end of the lesson, you will be able to recognize important minerals and learn about their significance to society.