2 What is a Mineral? Mineral Characteristics Naturally occurring InorganicSolidDefinite chemical compositionEither elements or compoundsHave orderly arrangements of atomsCrystalline/Set atomic pattern
3 The Structure of Minerals CrystalsSolids in which the atoms are arranged in orderly, repeating patterns.Minerals are classified into six major crystal systems according to their crystal structures:HexagonalCubicTetragonalOrthorhombicMonoclinicTriclinic
4 The Structure of Minerals Formation of Crystals:From the cooling and solidification of magmaThe 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 – largeFast – littleFrom the evaporation of a solution or the supersaturating of a solution
5 Mineral Compositions and Groups Mineral Classification2 Main Groups:SilicatesMinerals that contain silicon and oxygenContain most of the common rock-forming mineralsNonsilicatesDo not contain silicon
6 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 Earth’s crust.
7 Identification of Minerals HardnessA measure of how easily a mineral can be scratchedMeasured on a scale of 1 to 10 called the Mohs Scale.10 = hardest, diamond1 = softest, talcIron nail = 4.5Fingernail = 2.5
8 Identification of Minerals LusterThe way a mineral reflects light.Metallic or nonmetallic
9 Identification of Minerals Specific GravityRatio 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.
10 Identification of Minerals StreakColor of a mineral in a powder formFound by rubbing the mineral across a porcelain streak plate
11 Identification of Minerals CleavageMineral breaks along smooth, flat surfacesDue to the atomic arrangement of the mineral
12 Identification of Minerals FractureFractureMineral breaks along rough, uneven, or jagged surfaces.
13 Identification of Minerals Color and AppearanceColor and AppearanceHighly unreliable.
14 Identification of Minerals Other PropertiesOther propertiesMagneticOpticsChemical reactions
15 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 colorfulHave a slightly different chemical formula:Amethysts are quartz with a trace amount of iron.Have a better crystal structure.
16 Gems Important Gems Cullinan Diamond Hope Diamond Largest uncut diamond discoveredFound in South Africa in 19053, carats (621 g)Cut into 9 main stones and 96 smaller stonesLargest of these, the Great Star of Africa ( carats) is part of the British crown jewels.Hope DiamondPurchased by Henry Philip Hope around 1830.45.52 carats (9 g)All Hope’s family plus a later owner suffered misfortune.Currently on display in the Smithsonian.
17 Gems Useful Gems Diamonds Rubies Quartz Used as industrial abrasives and cutting toolsRubiesProduce certain types of laser lightQuartzUsed in timepieces and electronics
18 Useful Elements in Minerals OresA mineral or rock that contains a useful substance that can be mined at a profitExamples:Iron is found in the ores hematite and magnetiteAluminum is found in the ore bauxite
19 Useful Elements in Minerals Extracting ElementsRefiningWanted element is separated from unwanted materials.SmeltingThe substance is melted to separate it from any remaining unwanted materials.
20 Useful Elements in Minerals Vein MineralsOccur when dissolved metallic elements travel in fluid form through weaknesses in rock and form mineral deposits.
21 Useful Elements in Minerals TitaniumFound in ilmenite and rutile.Lightweight and durableUsed in auto body parts, aircraft, eyeglasses, etc.