AUFC+4.1

toc =4.1 Properties of Minerals=

Vocabulary

 * inorganic:** Not formed of living things or from the remains of living things
 * crystal:** A solid in which the atoms are arranged in a pattern that repeats again and again
 * element**: A substance composed of a single kind of atom
 * compound:** A substance in which two or more elements are chemically joined
 * Mohs hardness scale:** A scale ranking ten minerals from softest to hardest; used in testing the hardness of minerals
 * streak:** The color of a mineral's powder
 * luster:** The way a mineral reflects light from its surface
 * cleavage:** A mineral's ability to split easily along flat surfaces
 * fracture:** The way a mineral likes like when it breaks apart in an irregular way
 * fluorescence:** The property of a mineral in which the mineral glows under ultraviolet light

What is a Mineral?

 * geologist have already identified over 3,000 mineral
 * only 100 minerals are common
 * about 20 mineral make up earths surface
 * a mineral is an inorganic solid
 * a mineral always has a crystal structure
 * Naturally Occurring
 * minerals are not man made
 * Inorganic
 * mineral aren't made up of living things
 * since coal is made up of living things it is not a mineral
 * Solid
 * mineral must be solid
 * the particles must be packed together tightly
 * water is not a mineral since it is not solid
 * Crystal Structure
 * minerals need to have a crystal structure
 * crystal structures can sometimes be easy to identify but sometimes you can only identify it through a microscope
 * Definite Chemical Composition
 * a mineral always has certain elements in definite amounts
 * most minerals are compounds
 * a compound is a mineral that is made up of two or more elements combined[[image:Hardness_Scale_3.jpg width="368" height="368" align="right"]]

Identifying Minerals

 * in 1849, thousands of people went to California to find gold
 * few found gold, but many found minerals that look like gold
 * Hardness
 * to identify a mineral, finding the mineral's hardness is very useful
 * in 1812, Friedrich Mohs made the Mohs hardness scale
 * it ranks then minerals from softest to hardest
 * Color
 * it is easy to see what a mineral's color is
 * but a certain type of mineral can form in many different colors
 * Streak
 * the streak is the color of the mineral's powder
 * the color of the streak always stays the same color
 * Luster
 * minerals that look shiny is usually because they have metals inside them
 * Galena contains led and has a metallic luster
 * Malachite contains copper so it has a silky luster
 * Density
 * every mineral has its own density
 * the size doesn't change anything, its density will always stay the same
 * to compare the density you can lift 2 minerals that are the same size, one will probably weigh heavier
 * geologist measure the density of minerals by...
 * using a balance
 * place mineral in water to see how much water it displaces
 * dividing the mineral's mass by it volume
 * Crystal Systems
 * crystal structures are what kind of structure the atoms of the minerals grow into
 * there are six different structures so geologists seperate them into six different groups
 * crystals that grow in tight spaces are usually incomplete
 * crystal that grow in open spaces are almost perfectly complete
 * Cleavage and Fracture
 * identifying how a mineral breaks can help figure out what kind of mineral it is
 * a mineral that can break easily along flat surfaces have cleavage
 * have cleavage matters how the atoms in the mineral are arranged
 * if it is formed in a certain way, it'll be easier to break on one side than the other
 * most minerals don't split perfectly, this means the mineral is fractured
 * soft minerals have an earthy fracture
 * such as clay
 * rough minerals have an uneven fracture
 * Special Properties
 * minerals that glow under ultra-violet light have fluorescence
 * scheelite is fluorescent
 * some minerals contain magnetism
 * the mineral lodestone contains magnetism
 * a few minerals are radioactive
 * Uraninite can set off a Geiger counter
 * some minerals react chemically to acid
 * calcite will give off carbon dioxide if it touches vinegar
 * even some minerals have electrical properties
 * quartz has electrical properties

Back to AUFC Homepage