Presentation on theme: "Minerals Chapter 3. What is a Mineral? Mineral Characteristics Naturally occurring Inorganic Solid Definite chemical composition Either elements or compounds."— Presentation transcript:
Minerals Chapter 3
What is a Mineral? Mineral Characteristics Naturally occurring Inorganic Solid Definite chemical composition Either elements or compounds Have orderly arrangements of atoms Crystalline/Set atomic pattern
The Structure of Minerals Crystals Solids in which the atoms are arranged in orderly, repeating patterns. Minerals are classified into six major crystal systems according to their crystal structures: Hexagonal Cubic Tetragonal Orthorhombic Monoclinic Triclinic
The Structure of Minerals Formation of Crystals: From the cooling and solidification of magma The type and amounts of elements present in the magma partly determine which minerals will form. How rapidly the magma cools determines the size of the crystals. Slow – large Fast – little From the evaporation of a solution or the supersaturating of a solution
Mineral Compositions and Groups Mineral Classification 2 Main Groups: Silicates Minerals that contain silicon and oxygen Contain most of the common rock- forming minerals Nonsilicates Do not contain silicon
Mineral Compositions and Groups Mineral Amounts: About 4,000 different mineral are found on Earth. Only a few dozen of these minerals are common. 90 elements occur naturally in the crust of the Earth. ~98% of the crust is made of only eight elements. Silicon and Oxygen are two of the most abundant elements found in Earths crust.
Identification of Minerals Hardness A measure of how easily a mineral can be scratched Measured on a scale of 1 to 10 called the Mohs Scale. 10 = hardest, diamond 1 = softest, talc Iron nail = 4.5 Fingernail = 2.5
Identification of Minerals Luster The way a mineral reflects light. Metallic or nonmetallic
Identification of Minerals Specific Gravity Ratio of the weight of the mineral with the weight of an equal volume of water. Specific gravity of minerals can be roughly relatively tested using heft.
Identification of Minerals Streak Color of a mineral in a powder form Found by rubbing the mineral across a porcelain streak plate
Identification of Minerals Cleavage Mineral breaks along smooth, flat surfaces Due to the atomic arrangement of the mineral
Identification of Minerals Fracture Mineral breaks along rough, uneven, or jagged surfaces.
Identification of Minerals Color and Appearance Highly unreliable.
Identification of Minerals Other Properties Other properties Magnetic Optics Chemical reactions
Gems Properties of Gems Gemstones are highly prized minerals because they are rare and beautiful. Most gems are special varieties of a particular mineral. Clearer, brighter, or more colorful Have a slightly different chemical formula: Amethysts are quartz with a trace amount of iron. Have a better crystal structure.
Gems Important Gems Cullinan Diamond Largest uncut diamond discovered Found in South Africa in , carats (621 g) Cut into 9 main stones and 96 smaller stones Largest of these, the Great Star of Africa ( carats) is part of the British crown jewels. Hope Diamond Purchased by Henry Philip Hope around carats (9 g) All Hopes family plus a later owner suffered misfortune. Currently on display in the Smithsonian.
Gems Useful Gems Diamonds Used as industrial abrasives and cutting tools Rubies Produce certain types of laser light Quartz Used in timepieces and electronics
Useful Elements in Minerals Ores A mineral or rock that contains a useful substance that can be mined at a profit Examples: Iron is found in the ores hematite and magnetite Aluminum is found in the ore bauxite
Useful Elements in Minerals Extracting Elements Refining Wanted element is separated from unwanted materials. Smelting The substance is melted to separate it from any remaining unwanted materials.
Useful Elements in Minerals Vein Minerals Occur when dissolved metallic elements travel in fluid form through weaknesses in rock and form mineral deposits.
Useful Elements in Minerals Titanium Found in ilmenite and rutile. Lightweight and durable Used in auto body parts, aircraft, eyeglasses, etc.