Minerals

What is a mineral? Any substance that: 1)Is naturally occuring. 2)Is solid 3)Is organic 4)Has a definite chemical composition. 5)Has a crystal system

Naturally Occuring Anything that is found/created in nature. Most minerals are formed: –F–From cooled water solutions. –F–From Cooled magma –F–From evaporation of solutions.

Inorganic: Any material that did not form from living material. - Some rocks are organic (coal, limestone).

Definite Chemical Composition A mineral will always have certain elements in distinct proportions. - Some are pure elements: EX: Gold = Au Silver = Ag - Some are compounds: EX: Pyrite = FeS 2 Quartz = SiO 2

Crystal Systems Crystal Structure: The Repeating Pattern of a mineral’s particles. -S-Shape of the crystal depends on its definite chemical composition. -S-Size depends on how quickly the mineral cooled. -T-The faster = smaller -T-The smaller = larger

Mineral properties There are 8 characteristics that are unique between different minerals. –H–Hardness –L–Luster –S–Streak –B–Breakage –C–Crystal shape –C–Color –S–Special Properties –D–Density (Specific Gravity)

hardness The measure of how easily a mineral can be scratched. Moh’s Hardness Scale -T-Tested by performing a scratch test. -O-On a scale = softest (Talc) 10 = hardest (diamond)

Luster How a mineral reflects light. - EX: Metallic Glassy/Vitreous

Streak Color left behind by a mineral. Tested by: Scraping a mineral against a piece of unglazed tile and observing the color left behind.

breakage How a mineral breaks apart. 2 ways a mineral can break: 1) Cleavage: Breaks with clean smooth edges. 2) Fracture: Breaks with rough uneven edges.

Crystal systems The shape of a mineral’s crystal. Determined by the chemical composition. Common: –Hexagonal –Cubic –Triclinic –Monoclinic

Color and Density Color: The color of the mineral itself. -C-Cannot be used alone to identify a mineral because many minerals can come in many different colors. Density (specific gravity): How much a mineral weighs depending on how big it is. D = m/v (mass/volume)

Special properties Some minerals exhibit unique characteristics -M-Magnetism -R-Radioactivity -F-Fluorescence -E-Etc…

How are these used? We use these 8 properties to identify an unknown mineral. - Tests are performed and compared to known minerals and their properties.