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Minerals. Chapter 9.1. Minerals. Minerals A mineral is a natural inorganic, crystalline solid found in the Earth’s crust. An inorganic substance is one that is not made up of living things or the remains of living things.
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Minerals Chapter 9.1
Minerals • Minerals • A mineral is a natural inorganic, crystalline solid found in the Earth’s crust. • An inorganic substance is one that is not made up of living things or the remains of living things. • Every mineral is unique and can be made up of a single element such as copper or a compound of elements such as pyrite.
What is a Mineral? • What is a Mineral? • There are four main questions to answer when identifying if a substance is a mineral or not. • Is a substance inorganic? • Coal is organic and not a mineral. • Does the substance occur naturally? • Silver occurs naturally while steel does not.
What is a Mineral? • Is the substance a solid in crystalline form? • Natural gas is not a solid. • Does the substance have a definite chemical composition? • Halite is made of sodium and chlorine and has a specific crystalline pattern. While concrete is made up of several substances, the amounts of the substances changes depending on the use of the concrete.
Kinds of Minerals • Kinds of Minerals • Over 3,000 minerals have been identified, but fewer than 20 are common. • Out of the 20 common minerals, 10 of them make up 90% of the mass of the Earth’s crust.
Kinds of Minerals • All minerals can be classified into two main groups: silicate and non-silicate minerals. • Silicate minerals contain atoms of silicon and oxygen. • While quartz only consists of silicon and oxygen, most silicate minerals also contain one or more other elements. • Silicate minerals make up 96% of the Earth’s crust and 50% of the Earth’s crust is made up of feldspar minerals.
Kinds of Minerals • Non-silicate minerals do not contain silicon. • Only 4% of the Earth’s crust is made up of nonsilicate minerals. • Nonsilicate minerals are classified into six major groups. • Carbonates • Halides • Native elements • Oxides • Sulfates • Sulfides
Crystalline Structure • Crystalline Structure • All minerals in the Earth’s crust have a crystalline structure. • Crystalline structures are characterized by a specific geometric arrangement of atoms or ions.
Crystalline Structure • A crystal is a natural solid with a definite internal patter. • Most of the time this crystalline structure is can only be seen under a microscope. However, some crystalline structures can easily be seen such as calcite, quartz, and halite. • There are six crystalline shapes that can form and help identify minerals.
Crystalline Structure • Crystalline Structure and Silicates • While there are many silicate minerals, they are all made up of the same basic building blocks.
Crystalline Structure • This basic building block consists of four oxygen atoms arranged in a pyramid with one silicon atom in the center. • This structure is known as the silicon-oxygen tetrahedron. • This tetrahedron combines in many different arrangements to produce the many silicate minerals.
Tetrahedral Arrangements • Types of Tetrahedral Arrangements • The isolated tetrahedral silicates contain tetrahedrons that are linked by atoms other than silicon and oxygen. • Ring silicates for when the tetrahedral are joined into three, four, or six-sided rings by oxygen atoms.
Tetrahedral Arrangements • In a single-chain silicate, each tetrahedron is bonded to two others by shared oxygen atoms. • In double-chain silicates, two single chains of tetrahedral bond to each other. • In sheet silicates, each tetrahedron shares three oxygen atoms with other tetrahedra and the fourth oxygen atom is bonded with potassium or aluminum which joins one sheet to another.
Tetrahedral Arrangements • In a framework silicate, each tetrahedron is bonded to four neighboring tetrahedra. • The mineral quartz is formed by only silicon-oxygen tetrahedrons. However, other minerals can be formed by replacing the silicon atom of the tetrahedron with another element such as aluminum. This creates the feldspars.