2What is a Mineral? Mineral Characteristics Naturally occurring InorganicSolidDefinite chemical compositionEither elements or compoundsHave orderly arrangements of atomsCrystalline/Set atomic pattern
3The 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
4The 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
5Mineral Compositions and Groups Mineral Classification2 Main Groups:SilicatesMinerals that contain silicon and oxygenContain most of the common rock-forming mineralsNonsilicatesDo not contain silicon
6Mineral 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.
7Identification 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
8Identification of Minerals LusterThe way a mineral reflects light.Metallic or nonmetallic
9Identification 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.
10Identification of Minerals StreakColor of a mineral in a powder formFound by rubbing the mineral across a porcelain streak plate
11Identification of Minerals CleavageMineral breaks along smooth, flat surfacesDue to the atomic arrangement of the mineral
12Identification of Minerals FractureFractureMineral breaks along rough, uneven, or jagged surfaces.
13Identification of Minerals Color and AppearanceColor and AppearanceHighly unreliable.
14Identification of Minerals Other PropertiesOther propertiesMagneticOpticsChemical reactions
15Gems 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.
16Gems 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.
17Gems Useful Gems Diamonds Rubies Quartz Used as industrial abrasives and cutting toolsRubiesProduce certain types of laser lightQuartzUsed in timepieces and electronics
18Useful 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
19Useful Elements in Minerals Extracting ElementsRefiningWanted element is separated from unwanted materials.SmeltingThe substance is melted to separate it from any remaining unwanted materials.
20Useful Elements in Minerals Vein MineralsOccur when dissolved metallic elements travel in fluid form through weaknesses in rock and form mineral deposits.
21Useful Elements in Minerals TitaniumFound in ilmenite and rutile.Lightweight and durableUsed in auto body parts, aircraft, eyeglasses, etc.