What is a mineral? Naturally occurring Naturally occurring Solid substance Solid substance Orderly crystalline structure Orderly crystalline structure Definite chemical composition Definite chemical composition Generally INORGANIC Generally INORGANIC Some animals secrete inorganic compounds (Calcium carbonate found in shells and coral reefs) Some animals secrete inorganic compounds (Calcium carbonate found in shells and coral reefs)

Characteristics of Minerals More than 4000 minerals identified, but only 20 are commonly found More than 4000 minerals identified, but only 20 are commonly found Those 20 are known as rock- forming minerals, form the rocks of Earth’s crust Those 20 are known as rock- forming minerals, form the rocks of Earth’s crust Of the 20 most common, half of them make up 90% of the mass of Earth’s crust Of the 20 most common, half of them make up 90% of the mass of Earth’s crust

Groups of Minerals Minerals are classified by the elements they are made of. Minerals are classified by the elements they are made of. Amethyst Beryl (Emerald) Calcite

Mineral Group CharacteristicsExamples Silicates Contain oxygen & silica Contain oxygen & silica The most abundant group of minerals (95%) The most abundant group of minerals (95%) Quartz, mica MICA Quartz

Mineral Group CharacteristicsExamples Non-Silicates Make up only 5% of the Earth’s crust Make up only 5% of the Earth’s crust Include some of the most important minerals Include some of the most important minerals iron, copper, gold, silver, diamonds, rubies Silver Gold Ruby Iron Copper Diamond

Mineral Group CharacteristicsExamples Carbonates Carbon & oxygen and a positive ion, such as calcium Carbon & oxygen and a positive ion, such as calcium Calcite (CaCO 3 ) Calcite with Duftite inclusions

Mineral Group CharacteristicsExamples Oxides  Metallic ion and oxygen Hematite (Fe 2 )O 3

Mineral Group CharacteristicsExamples Sulfides  Sulfur and a metallic ion Galena (PbS)

Mineral Group CharacteristicsExamples Sulfates  Metallic ion, Sulfur & oxygen Barite (BaSO 4 ) Barite on Calcite BaSo4 / CaCO3 Barite BaSo4

Mineral Group CharacteristicsExamples Native Elements  Single elements Gold (Au), Diamond (C), Silver (Ag)

Chemical Formulas to Know Gold - Au Gold - Au Silver - Ag Silver - Ag Copper - Cu Copper - Cu Sulfur - S Sulfur - S Diamond - C Diamond - C Graphite - C Platinum - Pt Graphite - C Platinum - Pt Quartz - SiO 2 Quartz - SiO 2 Olivine - (Mg, Fe) 2 SiO 4 Olivine - (Mg, Fe) 2 SiO 4 Hematite - Fe 2 O 3 Hematite - Fe 2 O 3 Magnetite - Fe 3 O 4 Magnetite - Fe 3 O 4 Corundum - Al 2 O 3 Corundum - Al 2 O 3 Galena - PbS Galena - PbS Sphalerite - ZnS Sphalerite - ZnS Pyrite - FeS 2 Pyrite - FeS 2 Halite - NaCl Halite - NaCl Fluorite - CaF 2 Fluorite - CaF 2 Calcite - CaCO 3 Calcite - CaCO 3

Crystal Structure All minerals have a crystalline structure All minerals have a crystalline structure A crystal is a solid whose atoms, ions, or molecules are arranged in a regular, repeating pattern A crystal is a solid whose atoms, ions, or molecules are arranged in a regular, repeating pattern Each type of mineral crystal is defined by a specific geometric arrangement of atoms Each type of mineral crystal is defined by a specific geometric arrangement of atoms

Physical Properties of Minerals Color Color Luster Luster Streak Streak Hardness Hardness Cleavage Cleavage Fracture Fracture Crystal System Crystal System Density Density Special Properties Special Properties

Physical Properties of Minerals (can be used to identify the mineral) Color Can be misleading Can be misleading For example, Quartz comes in a variety of colors For example, Quartz comes in a variety of colors Can vary with the type of impurities Can vary with the type of impurities

Physical Properties of Minerals (can be used to identify the mineral) Luster Surface reflection Surface reflection metallic = shiny like metal metallic = shiny like metal non-metallic = dull, non-shiny surface non-metallic = dull, non-shiny surface Pyrite has a metallic luster Calcite has a non-metallic luster

Non-metallic Luster Non-Metallic lusters include: Non-Metallic lusters include: Vitreous (glassy) Vitreous (glassy) Pearly (pearl-like) Pearly (pearl-like) Silky (fiber-like) Silky (fiber-like) Earthy (dull) Earthy (dull)

Non-metallic luster Continued. Non-metallic lusters include: Non-metallic lusters include: Waxy (greasy appearance) Waxy (greasy appearance) Adamantine (diamond-like) Adamantine (diamond-like) Resinous (plastic-looking) Resinous (plastic-looking)

Physical Properties of Minerals (can be used to identify the mineral) Streak The color of the powdered form of the mineral The color of the powdered form of the mineral The color of the streak can be different than the mineral The color of the streak can be different than the mineral Minerals must be softer than the streak plate Minerals must be softer than the streak plate

Streak…can help identify quartz

Can oil and natural gas be classified as minerals? Why or why not? Answer: Oil and natural gas cannot be classified as minerals, because they are not solids, do not form crystals, and do not have a definite chemical make-up Answer: Oil and natural gas cannot be classified as minerals, because they are not solids, do not form crystals, and do not have a definite chemical make-up

Physical Properties of Minerals (can be used to identify the mineral) Cleavage & Fracture The way the mineral breaks The way the mineral breaks Cleavage—minerals break along smooth, flat surfaces and every fragment has the same general shape Cleavage—minerals break along smooth, flat surfaces and every fragment has the same general shape Fracture—minerals that break at random with rough or jagged edges Fracture—minerals that break at random with rough or jagged edges

Types of Cleavage Basal - 1 plane Basal - 1 plane Prismatic - 2 planes Prismatic - 2 planes Cubic Cubic Rhombohedral - 3 planes 90 Rhombohedral - 3 planes 90 Octahedral - 4 planes Octahedral - 4 planes Dodecahedral - 6 planes Dodecahedral - 6 planes

Types of Fracture Conchoidal – curved Conchoidal – curved Irregular – uneven Irregular – uneven Fibrous – splintery Fibrous – splintery Hackly – jagged-edged Hackly – jagged-edged

Physical Properties of Minerals (can be used to identify the mineral) Hardness How easily a mineral scratches materials How easily a mineral scratches materials Mohs Hardness Scale Mohs Hardness Scale Scale from 1 (softest) to 10 (hardest) Scale from 1 (softest) to 10 (hardest) Test by seeing if the mineral can scratch different objects (like human fingernail, copper, penny, glass, steel file) Test by seeing if the mineral can scratch different objects (like human fingernail, copper, penny, glass, steel file) 2.5, 3.5, 5.5, , 3.5, 5.5, 6.5

Crystal System Crystal form is the visible expression of a mineral’s internal arrangement of atoms Crystal form is the visible expression of a mineral’s internal arrangement of atoms Every mineral has a crystal form Every mineral has a crystal form

Density

Special Properties Magnetism  Attraction to magnets Magnetism  Attraction to magnets Smell & taste Smell & taste Fluorescence  glows under UV light Fluorescence  glows under UV light Phosphorescence  glows after UV light is off (stores light energy longer) Phosphorescence  glows after UV light is off (stores light energy longer)

Special Properties Effervescence  fizzing (HCl on calcite) Effervescence  fizzing (HCl on calcite) Chatoyancy  silky band when light shined on mineral Chatoyancy  silky band when light shined on mineral Asterism  six-sided star appears when light Asterism  six-sided star appears when light

Special Properties Double refraction – light is bent, causing image to be doubled Double refraction – light is bent, causing image to be doubled Ex. Calcite Ex. Calcite Radioactivity Geiger counter Radioactivity Geiger counter

Describe what would happen if you rubbed a mineral with a Mohs hardness value of 7 against a mineral with a value of 5. The one with a hardness of 5 would be scratched, because the mineral with a hardness of 7 is harder. The one with a hardness of 5 would be scratched, because the mineral with a hardness of 7 is harder.