What are they? Minerals are the building blocks of rocks. Minerals are chemical compounds made up of two or more of the naturally occurring elements Most minerals form when one of the metals combines with another element.
Criteria to be a mineral 1. Solid State 2. Naturally Occurring 3. Inorganic 4. Made up on specific elements 5. Definite crystalline shape
Which of these are minerals? • Halite (salt) • Steel • Gold • Cement • Oxygen • Diamond • Coal • Glass • Graphite • Wood • Sulfur • Ice • Sugar • Silver • Copper
Composition Combinations of only nine elements account for 95% of the minerals found in the lithosphere: Reactive Elements 8. Oxygen 9. Hydrogen Others: The elements: carbon, chlorine and sulphur occur in smaller quantities but also form important components of many minerals Metals • 1. silicon • 2. aluminum • 3. iron • 4. calcium • 5. sodium • 6. potassium • 7. magnesium
Identifying Minerals Each mineral has unique properties that help identify them. To identify rocks, you need to identify the minerals they contain. Properties: features that a material or object has
Properties of minerals Colour Lustre Texture Streak Cleavage/ Fracture Hardness
Color • Useful starting point as it is the first property you notice • Unfortunately, when looking at gold and pyrite, colour alone cannot identify the mineral. Not all minerals are the same colour all the time
Lustre • The way the surface of a mineral reflects light. • Words to describe lustre: • Metallic (Shiney) • Pearly • Glassy • Waxy • Silky • Greasy
Texture How does the mineral feel? Gritty or sandy? Powdery or chalky? Smooth like glass? Sharp like metal? Soapy or greasy? Smooth like wax?
Streak • The colour of powder that it leaves behind when you rub it across a surface • (A streak is the colour of the powdered form of the mineral) • Not always the same as the color of mineral • Use a white tile to scratch the mineral
Cleavage and Fracture • When you break a mineral the way in which it breaks tells you about the mineral • Cleavage: if it splits into two smooth surfaces • Fracture: mineral breaks with rough and uneven surfaces
Hardness • The hardness of a mineral is measured by how easily it can be scratched • In 1812, Friedrich Mohsdeveloped a scale of ten minerals, using a "hardness" value of 1 to 10. • Mohs Scale of Hardness • A mineral sample is tested by determining the highest rated mineral it can scratch and the lowest rated mineral that can scratch it
Mohs Scale of Hardness • Consists of 10 minerals ranked in order of hardness • The scale is a list of minerals arranged from softest (No. 1) to hardest (No. 10) which is used to determine the hardness of all other minerals. • 2.5 Fingernail • 3.5 Copper Penny • 4.5 Iron Nail • 5.5 Glass • 6.5 Steel File
Mineral Testing In partners you will be testing a variety of different minerals using the properties we discussed.