Mineralogy: Characteristics and Importance of Minerals

30 Questions

Which type of texture is characterized by interlocking crystalline grains greater than 1-2 cm in diameter?

Pegmatitic

What type of lava flow has a smooth, ropy surface texture?

Pahoehoe lava

Which type of texture is characterized by crystals that are too small to distinguish without magnification?

Aphanitic

What type of lava flow has a rough, jagged surface with sharp blocks and protruding spines?

Aa lava

Which type of texture is formed by very rapid cooling of magma, resulting in an amorphous, non-crystalline structure?

Glassy

Which type of texture is found in both intrusive and extrusive igneous rocks?

Porphyritic

What type of mineral is gold (Au)?

Native Element

Which of the following is a common sulfide mineral?

Pyrite

What is the main difference between anhydrous and hydrous sulfates?

Anhydrous sulfates contain water, while hydrous sulfates do not.

Which property of carbonate minerals can be used to identify the presence of calcium carbonate?

They react with hydrochloric acid and fizz.

What is the main difference between native elements and halides?

Native elements are composed of a single element, while halides are composed of a halogen element and an alkali or alkali earth element.

What is the main characteristic of igneous rocks?

They are composed of one or more minerals.

What is the primary characteristic that defines a mineral?

Having a definite chemical composition and ordered internal structure

Which of the following statements about ore minerals is true?

Ore minerals are mined and processed for the elements they contain

Which of the following is an example of an ore mineral?

Galena

Which property of minerals is described as the resistance to scratching or abrasion?

Hardness

What is the distinguishing characteristic of a mineral compared to a rock?

Minerals have a definite chemical composition, while rocks do not

Which of the following statements about minerals is true?

Minerals can be made of a single element or compounds in fixed proportions

What is the key characteristic of minerals that break along fractures rather than cleavage planes?

They break in uneven, splintery, or conchoidal patterns.

What is the relationship between a mineral's specific gravity and water?

A mineral with a specific gravity of 1 is equal in weight to an equal volume of water.

Which of the following statements about measuring specific gravity is true?

Specific gravity can be measured using simple procedures involving beakers and water displacement.

What term is used to describe very fine-grained rocks?

Aphanitic

Which of the following minerals would be classified as a silicate?

Quartz

What causes ions to slow down during crystallization?

Loss of energy

What distinguishes ferromagnesian silicate minerals from non-ferromagnesian silicates?

Ferromagnesian silicates contain iron or magnesium joined to the silicate structure.

What factor leads to the formation of large crystals in rocks?

Slow cooling rates

What term describes rocks with both coarse and fine-grained textures?

Porphyritic

Which of the following is an example of an oxide mineral?

Magnetite

Which factor affects the size of crystal grains in an igneous rock?

Rate at which molten cools

What are phenocrysts in igneous rocks?

Larger grains than the rest of the rock

Study Notes

Igneous Rock Textures

Groundmass: fine-grained component of a porphyritic rock that forms when magma or lava cools
Types of textures:
Phaneritic: coarse-grained rocks that form below the Earth's surface
Aphanitic: very fine-grained rocks with crystals too small to distinguish without a magnifying lens
Porphyritic: contains both coarse and fine-grained textures
Glassy: formed by very rapid cooling of magma, amorphous with no crystalline structure
Pegmatitic: contains interlocking crystalline grains > 1-2 cm in diameter

Lava Types

Aa lava: basaltic lava flow with a rough surface, characterized by sharp, jagged blocks and protruding spines of volcanic rock
Pahoehoe lava: basaltic lava flow with a smooth and twisty, rope-like surface

Mineral Classification

Native Elements: composed of a single native element (e.g. Au, Ag, Cu, Fe, diamonds, graphite, platinum)
Halides: consist of halogen elements (Cl, Br, F, I) forming strong ionic bonds with alkali and alkali earth elements (e.g. Halite, Fluorite)
Sulfates: minerals that include SO4 anionic groups combined with alkali earth and metal cations (e.g. Barite, Gypsum)
Carbonates: anionic groups of carbon and oxygen, react with hydrochloric acid (e.g. Calcite, Calcium carbonate, Dolomite)
Sulfides: minerals composed of one or more metal cations combined with sulfur (e.g. Pyrite, Galena, Cinnabar, Molybdenite)

Characteristics of Minerals

Definition: naturally occurring inorganic homogeneous solid with a definite chemical composition and ordered internal structure
Importance: used to define major periods of early human civilization (e.g. Stone Age, Chalcolithic Age, Bronze Age, Iron Age)

Ore Minerals

Minerals that are mined and processed for the elements they contain (e.g. Bauxite, Bornite, Chalcopyrite, Malachite)

Mineral Properties

1. Crystal Form
1. Hardness
1. Luster
1. Color
1. Streak
1. Cleavage
1. Specific Gravity: weight of a mineral relative to an equal volume of water

Learn about the characteristics and importance of minerals in geology and human civilization. Explore the definition of rocks, the concept of ore minerals, and the significance of mineral resources throughout different historical periods.

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