They’re everywhere!

What is a mineral?  A mineral: is naturally-occurring. ○ not manmade is an inorganic solid. ○ It has never been a part of a living thing. has a definite chemical composition. ○ It has specific elements that make up its compounds. ○ NaCl is always halite, which is table salt. It is a compound of sodium and chlorine. has an orderly arrangement of atoms. ○ Minerals are made of crystals, which have specific shapes. ○ All minerals are solids.

Atom Patterns in Minerals  Minerals are crystalline solids.  The atoms of minerals are arranged in patterns that repeat.

 A crystal is a solid in which the atoms are arranged in orderly, repeating patterns.  A crystal system is a group of crystals that has a similar atomic arrangement. a similar overall crystal shape.  The Structure of Minerals

Crystal Systems of Minerals  Hexagonal  Six-sided crystals  Examples: Emeralds Aquamarine

Crystal Systems of Minerals  Tetragonal  Example: Zircon Cassiterite from Madagascar Apophyllite

Crystal Systems of Minerals  Cubic  Examples: Halite, which is common table salt. Fluorite, which is an additive in toothpaste used to prevent cavities.

Crystal Systems of Minerals  Orthorhombic  Example: Sulfur Topaz

Crystal Systems of Minerals  Monoclinic  Example: Selenite gypsum

Crystal Systems of Minerals  Triclinic  Very little symmetry  Example: amethyst

More on crystals...  There are about 4000 different types of minerals on Earth.  Crystals that develop in a tight space will have small, barely visible crystal shapes.  Crystals that develop in open spaces will have more room to grow larger, visible crystal shapes.

Crystals from Magma  Hot, melted rock material that is under Earth’s crust is called magma.  Magma is loaded with compounds that can form minerals.  If magma cools slowly, the crystals have more time to form and can grow quite large.  If magma cools quickly, smaller crystals form and individual crystals can’t be seen.

Crystals from Solution  Crystals can form when minerals dissolve in water and the water evaporates.  ant-crystals-cave/ ant-crystals-cave/  Death Valley Salt fields were formed from halite that came out of solution as water evaporated.

Devil’s Golf Course, Death Valley, California

Mineral Compositions & Groups  Ninety-two elements occur naturally in Earth’s crust.  Most of Earth’s crust is composed of only 8 of these elements.  Silicates are minerals that contain a compound of silicon and oxygen bonded together, usually with another element. Silicon and oxygen are the two most abundant elements in Earth’s crust.