Chapter 9 : Rocks and Minerals

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Chapter 9 : Rocks and Minerals Section 1: Minerals—Earth’s Jewels

Ex of Minerals around us • Muscovite – used in insulators

Sulfur – used for matches, explosives, tires, fertilizers

Pyrite or Fool’s Gold Looks like gold but it is not. Used in jewelry

Magnetite – used to make magnets

Calcite - Used in medicines, soil conditioner, roadbed material, and building stone.

Feldspar – ceramics, glass, enamel, soap, false teeth and silverware.

optical instruments, and electrical devices. Used in making sand paper and grinding tools.

Pink Quartz – jewelry and ornamental objects

Amethyst – jewelry and medicines

Important characteristics of minerals 1)formed by natural processes – not man made 2)Minerals are inorganic – can’t come from plants or animals 3)Minerals have a definite chemical composition – formed always by the same types of chemical elements 4) Minerals are crystalline solids

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Composition: Most of the minerals are:

1) silicates which contain the chemical elements called silicon and oxygen 2) carbonates which contain the chemical elements called carbon and oxygen See all elements in the periodic table – back cover

Crystalline Solids Minerals are crystalline solids Crystalline means that the structure inside the minerals is arranged in repeating patterns Minerals are also called crystals

Different types of internal structure

Also the surfaces of minerals will show the repeating crystalline pattern

Final Definition of Minerals Minerals are: naturally occurring, inorganic, solid materials, with a definite chemical composition and a crystalline internal arrangement

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Rocks x Minerals

Rocks are usually made of two or more minerals. MINERALS are considered the

building blocks of rocks!

How do Minerals form? 4 processes 1) from magma 2) from lava 3) In processes that involve evaporation of liquids 4) In processes that involve precipitation of solids

1) From magma - melted rock that is inside the Earth will cool and form minerals inside the Earth 2) From lava - magma that reaches the Earth’s surface after volcanic eruptions will cool and form minerals the Earth’s surface

• The size of the crystals formed from magma or lava depend partially on how rapid the magma or the lava cools • Cools fast - crystals are small • Cools slow – crystals are bigger . Will have more time to form. • ** by the size of the crystals in a mineral, we can understand if the mineral was formed inside the earth or not.

How do minerals form? 2 more processes 3) Evaporation - salt and other minerals can crystallize when sea water evaporates 4) Precipitation – when there is too much dissolved materials in water, the excess can precipitate and form crystals

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Gems:

• are minerals that are rare and can be cut and polished, giving them a beautiful appearance. • Very expensive because they are rare • Ideal for jewelry

Geodes are holes in rocks that have crystals around the inside

Ores – are combinations of rocks and minerals • This combination of rocks and minerals is an ore only if:

• contains enough of a useful substance that it can be sold for a profit. • the ore must be extracted from Earth in a process called mining and then purified to obtain the valuable substance

Ore Processing • After an ore has been mined, it must be processed to extract the desired mineral.

Ores are melted to separate and remove most of the unwanted materials.

Examples of Ores: • steel comes from iron that is extracted from hematite • lead for batteries is produced from the mineral galena

• magnesium used in vitamins comes from the mineral dolomite.

Gold Ores

**Minerals are considered a nonrenewable resource • It takes millions of years to form minerals • It is important to recycle all materials obtained from minerals • To recycle iron and steel could reduce the extraction of the mineral hematite, protecting this natural resource