Minerals of the Earth’s Crust Chapter 3

What is a Mineral? Section 1 Four questions must be ask to figure this out Is it a solid? Minerals can’t be gases or liquids Is it formed in nature? Crystalline materials made by people aren’t classified as minerals Is it nonliving material? A mineral is inorganic, meaning it isn’t made of living things

What is a Mineral? Cont. Section 1 Does it have a crystalline structure? Minerals are crystals, which have a repeating inner structure that is often repeated in the shape of the crystal. Minerals generally have the same chemical composition throughout. Mineral = a naturally formed, inorganic solid with a crystalline structure

Minerals: From the Inside Out Section 1 Minerals: From the Inside Out To understand what crystalline structure is, you need to know about the elements that make up minerals. Elements = substances that cannot be broken down into simpler forms by ordinary chemical means. All minerals contain one or more of the 92 elements present in the Earth’s crust. Atom = the smallest part of an element that has all the properties of that element minerals are made up of atoms of one or more elements

Minerals: From the Inside Out – Cont. Section 1 Minerals: From the Inside Out – Cont. Compound = a substance made of two or more elements that have been chemically joined, or bonded together Crystals = solid, geometric forms of minerals produced by a repeating pattern of atoms that is present throughout the minerals. A crystal’s shape is determined by the arrangement of the atoms within the crystal. The arrangement of atoms in turn is determined by the kinds of atoms that make up the mineral.

Minerals: From the Inside Out – Cont. Section 1 Minerals: From the Inside Out – Cont. Crystal Structure Classifications: Isometric Hexagonal Tetragonal Orthorhombic Monoclinic Triclinic Page 61 – picture

Types of Minerals Section 1 Crystal Chemical Classifications: Silicate Minerals Silicate minerals = contain a combination of silicon & oxygen. Makes up 90% of the Earth’s crust. Can be other elements in these crystals. Feldspar – ½ the Earth’s crust (aluminum, potassium, sodium, & calcium) Mica – shiny & soft, they separate easily into sheets. Quartz – SiO2 (silicon dioxide)

Types of Minerals – Cont. Section 1 Types of Minerals – Cont. Nonsilicate Mineral Nonsilicate Mineral = don’t contain a combination of the elements silicon & oxygen. Native elements – minerals that composed of only one element (Au, Pt, C, Cu, S & Ag) Carbonates – minerals that contain combination of carbon & oxygen in their chemical structure. We use these minerals in cement, building stones, & fireworks.

Types of Minerals – Cont. Section 1 Types of Minerals – Cont. Halides – form when the atoms of elements F, Cl, I, Br, combine with Na, K, or Ca. Used to make fertilizer. Oxides –form when an element, (aluminum or iron) combines chemically with oxygen. Used to make abrasives, aircraft parts, & give false teeth a natural color.

Types of Minerals – Cont. Section 1 Types of Minerals – Cont. Sulfates – contain sulfur & oxygen. Used in cosmetics, toothpaste, & paint. Sulfides – contain one or more elements combined with sulfur. Used to make batteries, medicines, & electronic parts.

Identifying Minerals Section 2 How can you tell whether they are the same mineral? How can you determine the identity of a mineral? Color Property possessed by an object of producing different sensation on the eye as a result of the way the object reflects or emits light. Color can be helpful, but other properties should be used to identify minerals (because of factors such as weathering & impurities)

Luster Section 2 Luster = the way a surface reflects light Metallic luster – shiny or glassy look to it Submetallic luster – dull though some shine Nonmetallic luster – dull no shine on it Streak Streak = the color of a mineral in powered form The mineral is rubbed against a piece of unglazed porcelain called a streak plate. Streak is not affected by weathering so is more reliable than color

Cleavage & Fracture Section 2 Cleavage = the tendency of some minerals to break along flat surfaces Fracture = the tendency of some minerals to break unevenly along curved or irregular surfaces. Hardness Hardness = a mineral’s resistance to being scratched Mohs’ hardness scale – scale to determine a minerals hardness

Section 2 Density Density = the measure of how much matter there is in a given amount of space. Density = mass/volume Specific gravity – the ratio of an object’s density to the density of water Special Properties Fluorescence, chemical reaction, optical properties, taste, magnetism, radioactivity

The Formation & Mining of Minerals Section 3 The Formation & Mining of Minerals Minerals form in a large variety of environments under a variety of physical & chemical conditions The environment in which a mineral forms determines the mineral’s properties

Section 3 Mining Ore = geologists describe a mineral deposit large enough and pure enough to be mined for a profit. Surface Mining removal of minerals or other materials at or near the Earth’s surface (open pits, strip mines, & quarries) Deep Mining Removal of minerals or other materials form deep within the Earth (shafts, tunnels, & other passageways)

Common Uses of Minerals Section 3 The Value of Minerals Mineral crystals that are attractive & rare are called gems, or gemstones Common Uses of Minerals Mineral Metal Uses Chalcopyrite copper coins, electrical wire Galena lead batteries, paints Beryl beryllium bicycle frames, airplanes Chromite chromium stainless steel, cast iron, leather tanners

Responsible Mining Recycling reduces our need for these resources Section 3 Responsible Mining Mining can destroy or disturb the habitats of plants & animals The waste products from a mine can get into water sources, polluting both surface water & ground water Reclamation = return the land to its original state after the mining is completed The process is an expensive & time-consuming process Recycling reduces our need for these resources