© fall 2005, pflugerville isd, 8th gradeunit 3 : chapter 15 : section 1 what is a mineral? halite...

Unit 3 : Chapter 15 : Section 1© Fall 2005, Pflugerville ISD, 8th Grade

What is a Mineral?

Halite Crystal (NaCl)

•Natural, inorganic solid with a crystal structure.


Types of Minerals

•Minerals are grouped by the chemicals in them

•Silicate minerals contain silicon and oxygen.

Muscovite crystal under microscope


Silicate Minerals

Muscovite crystal under microscope

•Over 90% of the minerals in Earth’s crust are silicates.


Nonsilicate Minerals

Calcite (CaCO3)

•Nonsilicates are minerals that do not contain silicon.



Calcite (CaCO3)

•Nonsilicates are made of elements such as carbon, oxygen, iron and sulfur



Calcite (CaCO3)

•Carbonates, such as calcite, are used in cement, building stone, and fireworks. Carbonates contain carbon and oxygen.



Halite (NaCl)

•Halide minerals are used in fertilizer, or to season your food. Halides contain a halogen, such as chlorine, bromine, and iodine.



Corundum (Al2O3)

•Oxide minerals are used to make abrasives and aircraft parts. All oxides contain three atoms of oxygen.



Gypsum (CaSO4•2H2O)

•Sulfates are used in cosmetics, toothpaste, and paint. All sulfates contain sulfur and oxygen.

Unit A : Chapter 1 : Section 1© Fall 2005, Pflugerville ISD, 8th Grade


• Sulfides – All minerals in the sulfide group contain sulfur and a metal.

• Native elements – All minerals in this group are found on the periodic table.


Identifying Minerals

•Geologists use physical properties such as color, luster, streak, and many others to identify minerals



Quartz/Amethyst Scepter (SiO2)

•Quartz and amethyst are both SiO2, but amethyst contains impurities that give it a purple color.



Quartz/Amethyst Scepter (SiO2)

•Because a single mineral can be many colors, color is not a reliable way to identify a mineral.



Galena (PbS)- Metallic Luster

•The way the surface of a mineral reflects light is called luster



Bauxite (Al2O3•2H2O)- Earthy Luster

•Bauxite, the ore of aluminum, has a nonmetallic luster



•Streak is the color of a mineral in powdered form



•Hematite’s color may change, but its streak is always the same



Cleavage Planes

•Fluorite, halite, and calcite all have cleavage along flat

planes. Property of a mineral that allows it to break along smooth, flat planes is its cleavage.



Fracture

•Sulfur has fracture, meaning it breaks unevenly



•A mineral’s resistance to scratching it is called hardness



•Hardness is measured using Mohs’ hardness scale



•Density is another property used to identify minerals



•More ping-pong balls than golf balls are needed to balance the scale



•Which are more dense, golf balls or ping-pong balls?


From Minerals to Rocks

Minerals of Granite

•Rock is a solid mixture of crystals of one or more minerals



Coal Limestone•Some types of rock, such as coal and limestone are made of organic materials, not minerals


The Rock Cycle

•The rock cycle is the continuous process by which new rock is formed from old rock material


The Rock Cycle

•Each type of rock can be changed into every other type of rock


The Rock Cycle


Igneous: Rock From Magma

What are some positive and some negative effects that volcanoes have on

the people and places around them?

What Do You Think?



Lava Fountain

•All igneous rock starts out as magma inside the earth

Unit A : Chapter 1 : Section 1© Fall 2005, Pflugerville ISD, 8th Grade


Lava “Freezes” into Igneous Rock

•When magma or lava cools down enough, it becomes igneous rock



Intrusive Rock- Granite

•When magma cools beneath the earth’s surface, it forms intrusive igneous rock



Intrusive Rock- Granite

•Large crystals form, and intrusive rock has a coarse texture because it cools very slowly



Extrusive Rock- Obsidian

•Igneous rock that forms on the earth’s surface is called extrusive




•Extrusive rock cools quickly and does not have time to grow large crystals




•Extrusive rock has a fine-grained texture


Sedimentary: Rock FromOther Rocks

How are layers of sedimentary rock similar to the rings in a tree? How are they

different? What can geologists learn from studying sedimentary rock layers?

What Do You Think?



•Wind, water, ice, and pressure all cause rock to break into pieces



Rivers Transport Sediment

•In the process of erosion, rivers move sediment from one place to another



Sedimentary Rock Layers

•Finally, the sediment is deposited in layers



Sedimentary Rock Layers

•After compaction and cementation, sedimentary rock is formed



Calcite Flowstone

•Chemical sedimentary rock forms when minerals crystallize out of a solution of minerals and water



Coal Limestone•Organic sedimentary rocks such as coal and limestone form from the remains of living things


Metamorphic: Cooked Rock

When you mix up cookie dough, the mixture of ingredients is similar to sedimentary rock. How does the cookie dough change when

you place it in a hot oven?

What Do You Think?



Contact Metamorphism

•Metamorphic rocks are rocks that have been changed by heat and pressure

Unit 3 : Chapter 15© Fall 2005, Pflugerville ISD, 8th Grade

Let’s Review!

- 1 -What are the five

characteristics of a mineral?

How is a mineral different from a rock?


Let’s Review!

- 2 -How does the rate of

cooling affect the size of crystals in igneous

rocks?


Let’s Review!

- 3 -How does clastic

sedimentary rock form?How does chemical

sedimentary rock form?


Let’s Review!

- 4 -What changes occur when

heat and pressure are applied to a rock?

What kinds of rocks can become metamorphic?


http://webmineral.comhttp://mineral.galleries.comhttp://www.mindat.org/

http://webmineral.com/

http://mineral.galleries.com/

http://www.mindat.org/


Pre-AP Extensions

© fall 2005, pflugerville isd, 8th gradeunit 3 : chapter 15 : section 1 what is a mineral? halite...

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