Minerals of Earth’s Crust

What is a Mineral Minerals: Naturally occurring, usually inorganic solid, that has: A characteristic chemical composition An orderly internal structure A characteristic set of physical properties.

Characteristics of Minerals To determine if a substaqnce is a mineral or a non-mineral, we use 4 basic questions. Is it inorganic? Does it occur naturally? Is it a crystalline solid? Does it have a consistent chemical composition?

Characteristics of Minerals Is it inorganic? Inorganic substance is one that is not made up of living things, or the remains of living things. Coal = organic because it is composed of the remains of ancient plants Coal NOT A mineral……..

Characteristics of Minerals Does it occur naturally? Minerals form and exist in nature. Manufactured substances, such as steel or brass, are not minerals.

Characteristics of Minerals Is it a crystalline solid? Minerals have a repeating distinct structure. Volcanic glass (obsidian), atoms not arranged in regularly repeating crystalline structure, so not a mineral.

Characteristics of Minerals Does it have a consistent chemical composition? Distinct minerals have an unique consistent chemical composition….. Fluorite or quarts are minerals.

Kinds of Minerals We have identified 4,000 different minerals. Fewer than 20 are common. Rock Forming Minerals: They form the rocks that make up Earth’s crust. Of these 20, 10 make up 90% of the mass of the Earth’s crust.

Kinds of Minerals Silicate Minerals: A minerals that contains a combination of silicon (Si) and oxygen (O) Silicate minerals make up 96% of Earth’s crust. Feldspar and quartz alone make up more that 50%

Kinds of Minerals Non-Silicate Minerals: Approx. 4% of Earth’s crust made up of minerals that do not contain compounds of silicon and oxygen. 6 Major Classes of Non-silicate minerals Carbonates Halides Native elements Oxides Sulfates Sulfides

Crystalline Structure All minerals have a unique crystalline structure characterized by a specific geometric arrangement of atoms. A crystal is a solid whose atoms, ions, or molecules are arranged in a regular, repeating pattern.

Crystalline Structures of Silicate Minerals Even though there are many kinds of silicate minerals, their crystalline structures is made up of the same basic building blocks. Silicon-oxygen tetrahedron: Combine in different arrangements to form different minerals.

Crystalline Structures of Silicate Minerals Isolated tetrahedral Ring silicates Single-chain silicates Double chain silicates Sheet silicates Framework silicates

Crystalline Structures of Non-Silicate Minerals Great variety on crystal structures Crystal structure based on packing of atoms as close together as possible.