Transcript Slide 1
What is a Mineral? Naturally-formed, inorganic solid substance with a definite crystalline structure Pyromorphite What do all minerals have in common? All: 1. 2. 3. 4. 5. Are formed by natural processes. Are NOT alive and NEVER were alive Have a definite volume and shape Are elements or compounds with a unique chemical makeup Are made up of particles that are arranged in a pattern that is repeated over and over (called a CRYSTAL) Watch “Crystals” by Brainpop… 1.What element are diamonds made from? 2. What do all crystals have in common? Elements, Atoms, and Compounds Elements – pure substances that cannot be broken down into simpler substances by ordinary chemical means. All minerals contain one or more of the 92 naturally occurring elements. Example: oxygen, carbon, sulfur, hydrogen Atoms – 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. Compounds – a substance made of two or more elements that have been chemically joined. Example: water (H2O), salt (NaCl) Groups of Minerals Minerals are grouped by the elements they are made of. Beryl (Emerald) Calcite Amethyst Mineral Group Characteristics Contain Silicates oxygen & silicon The most abundant group of minerals Make up more than 90% of the Earth’s crust. MICA Examples Quartz, mica, feldspar Quartz Mineral Group Non-Silicates (native elements, carbonates, halides, oxides, sulfates, and sulfides) Silver Characteristics Do NOT contain silicon and oxygen Make up only 5% of the Earth’s crust Include some of the most important minerals Examples iron, copper, gold, silver, diamonds, rubies Copper Diamond Gold Ruby Iron Mineral Group Carbonates Characteristics Carbon & oxygen and a positive ion, such as calcium Used in cement, building stones, and fireworks. Examples Calcite (CaCO3) Calcite with Duftite inclusions Mineral Group Oxides Characteristics Metallic ion (aluminum/iron, etc.) and oxygen Used to make abrasives, aircraft parts, and paint. Examples Hematite (Fe2)O3 Mineral Group Sulfides Characteristics Sulfur and a metallic ion such as lead, iron, or nickel Used to make batteries, medicines, and electronic parts Examples Galena (PbS) Mineral Group Sulfates Barite on Calcite BaSo4 / CaCO3 Characteristics Metallic ion, Sulfur & oxygen Used in cosmetics, toothpaste cement, and paint. Barite BaSo4 Examples Barite (BaSO4) Mineral Group Native Elements Characteristics Single elements Examples Gold (Au), Diamond (C), Silver (Ag) How do minerals form? 1) Cooling of magma (hot, liquid rock and minerals inside the earth (from the mantle)) Fast Cooling = No Crystals (mineraloids) Medium Cooling = small crystals Slow Cooling = large crystals How do minerals form? 2) Elements dissolved in liquids (usually water) Physical Properties of Minerals (can be used to identify the mineral) Color Can be misleading Not the best way to identify a mineral Can vary with the type of impurities Physical Properties of Minerals (can be used to identify the mineral) Luster Surface reflection How shiny or dull an object is metallic = shiny like metal non-metallic = dull, non-shiny surface Pyrite has a metallic luster Calcite has a non-metallic luster Physical Properties of Minerals (can be used to identify the mineral) Streak The color of the mineral in powdered form The color of the streak can be different than the mineral Minerals must be softer than the streak plate Streak…can help identify quartz http://www.childrensmuseum.org/geomysteries/cube/b3.html Physical Properties of Minerals (can be used to identify the mineral) Hardness How easily a mineral scratches materials Mohs Hardness Scale 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) Find out more… “Electronic” Hardness Test http://www.childrensmuseum.org/geomy steries/cube/b2.html Physical Properties of Minerals (can be used to identify the mineral) Cleavage & Fracture The way the mineral breaks 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 Cleavage or Fracture? 1. 4. 2. 3. Physical Properties of Minerals (can be used to identify the mineral) Other Properties Specific gravity (*excellent clue to mineral’s identity) – the ratio of an object’s density to the density of water Attraction to magnets (magnetism) Fluorescence (glow under ultraviolet light) Bending of light (double images) Reaction with hydrochloric acid (chemical reaction) Smell & taste Watch Brainpop—“Mineral Identification” 1. If a mineral can scratch your fingernail, the mineral is _______________ than your fingernail. 2. What is luster?