Minerals Notes for Chapter 4

What is a mineral? A mineral is a substance that… Is naturally occurring Meaning NOT man-made Inorganic Not made from dead plant/animal matter Solid Not a liquid or a gas Crystal Structure Particles are set in a specific and fixed pattern Definite Chemical Composition Each element in the mineral has a specific proportion

Identifying Minerals Geologists know about 3800 minerals on Earth. To tell each one apart, they have written down characteristics. Currently – there are 7 basic characteristics

Identifying Minerals 7 Characteristics Streak Luster Density Hardness Crystal Structure Cleavage and Fracture Color

Identifying Minerals Color This trait refers to how the mineral looks on the outside. But – it can not be the only identifying mark as some minerals can have the same color and not be the same mineral. Can you tell which one is the “real” gold?

Identifying Minerals Streak Another clue into identifying a mineral is its streak. The streak of a mineral is the color of its powder. This is tested by taking the mineral and rubbing or “streaking” it on an unglazed porcelain tile.

Identifying Minerals Luster This is the “BlingBling” category. Luster is measured by how much light is reflected off the object.

Identifying Minerals Density D= m/v You remember this, right? This is how much stuff you have divided by how much space you put it in. No matter what size sample you have, the mineral will ALWAYS have the same density.

Identifying Minerals Hardness Moh’s Hardness Scale This is a “deal breaker” for identifying minerals. Austrian “Scientist Dude” Friedrich Mohs created a rating system for mineral hardness. Minerals are rated on how they can be scratched. See pages 118 and 119 in textbook. Moh’s Hardness Scale

Identifying Minerals Crystal Systems Geologists classify minerals according to 6 crystal forms based on the number AND angle of the crystal faces.

Identifying Minerals Cleavage and Fracture How a mineral breaks is as important as how it is formed. Cleavage breaks are clean without any jagged edges. Fracture breaks are messy with irregular surfaces.

Exceptions to the Rules Of course – this is science! Some minerals can have special properties…. Like fluorescence or magnetism or reactivity…

How do minerals form? There are two basics ways that minerals form on Earth. Magma and Lava Solutions

Minerals from Magma and Lava Minerals form when the hot magma cools inside the crust. Minerals form from lava when it hardens on the surface of the Earth. When these liquids hardens – they form crystals. Crystal size will depend on how fast the liquid cools. The faster it cools – the bigger the crystal size.

Minerals from Solutions A solution is when one substance is dissolved into another. Minerals can be created when their components are dissolved in a liquid. The liquid evaporates and the crystals of the mineral are left behind. Minerals can also form in a hot water solution – where the water is hotter than the mineral and the mineral cools.

Using Mineral Resources OK – Now you know how to find minerals and how to identify them – now what? Figure out how you can use them!!!!

Using Mineral Resources Gemstones and Jewelry Metals Foods and Medicine

Review for Test List 5 characteristics of minerals Define 7 properties of minerals Describe 2 ways minerals are formed Compare and contrast ways that minerals are used in everyday life

Review for Test List 5 characteristics of minerals Naturally occurring Inorganic Solid Crystal structure Specific chemical composition

Review for Test Define 7 properties of minerals Color Streak Luster Density Hardness Crystal Systems Cleavage and Fracture

Review for Test Describe 2 ways minerals are formed Magma and Lava Solutions Compare and contrast ways that minerals are used in everyday life Sounds like a great open – ended question!!!!

The End…. KLM ENTERPRISES 2008