Minerals

What are Minerals? Occurs naturally (not man-made) is a solid is a chemical compound arranged in an orderly pattern (crystals) is inorganic (not made from dead plants or animals) Is an element or a compound (unique chemical formula)

Mineral Groups Minerals are grouped by the elements they are made of Beryl (Emerald) Calcite Amethyst

Contain oxygen & silica The most abundant group of minerals Mineral Group Characteristics Examples Silicates Contain oxygen & silica The most abundant group of minerals Quartz, mica MICA Quartz

(contain oxygen but not silicon) Make up only 5% of the Earth’s crust Mineral Group Characteristics Examples Non-Silicates (contain oxygen but not silicon) Make up only 5% of the Earth’s crust Include some of the most important minerals iron, copper, gold, silver, diamonds, rubies Silver Copper Diamond Gold Ruby Iron

Carbon & oxygen and a positive ion, such as calcium Calcite (CaCO3) Mineral Group Characteristics Examples Carbonates Carbon & oxygen and a positive ion, such as calcium Calcite (CaCO3) Calcite with Duftite inclusions

Mineral Group Characteristics Examples Oxides Metallic ion and oxygen Hematite (Fe2)O3

Mineral Group Characteristics Examples Sulfides Sulfur and a metallic ion Galena (PbS) Pyrite (FeS2)

Metallic ion, Sulfur & oxygen Barite (BaSO4) Mineral Group Characteristics Examples Sulfates Metallic ion, Sulfur & oxygen Barite (BaSO4) Barite BaSo4 Barite on Calcite BaSo4 / CaCO3

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) will reform into crystals as the water evaporates and the dissolved elements recrystalize.

Physical Properties of Minerals (can be used to identify the mineral) Color Can be misleading Can vary with the type of impurities

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 streak can be different than the mineral Minerals must be softer than the streak plate

Streak…can help identify quartz BUT... http://www.childrensmuseum.org/geomysteries/cube/b3.html

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

Metallic Luster

Nonmetallic Luster

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)

Breaking Properties: Cleavage or Fracture Cleavage – mineral breaks along a flat surface or into sheets Fracture – when a mineral breaks with lots of jagged edges

Cleavage or Fracture? 1. 2. 4.

Extra Special Properties 1. Fluorescence Fluorescent color under ultraviolet (UV) light 2. Magnetic Attract magnets 3. Acid reaction Carbon dioxide gas bubbles off when you drop acid on them Carbonates!

Fluorescence

Magnetic

Carbonate Acid Reaction