Silicates And Carbonates

MineralGroups‐SilicatesandCarbonates

EarthScience–2ndSemester

•  Mineralscanbeclassifiedintogroupsbasedontheircomposi;on.

Silicates

•  Thetwomostabundantmineralsinearth’scon6nentalcrustaresiliconandoxygen.

•  Thesetwoelementscombinetoformanewstructurecalledthesilicon–oxygentetrahedron.

•  Thetetrahedronconsistsofonesiliconatomandfouroxygenatoms.

•  Itprovidestheframeworkforeverysilicatemineral,

Ex.Quartz.

•  Theinternalstructureoftheatomswillaffecttheproper6esoftheatom.

•  Example:Olivine–veryhardmineral,madefrommillionsoftetrahedronbondedtogether.

•  Mica–thetetrahedronjointogethertoformsheets.

•  Quartz–Formedbythree‐dimensionalnetworksoftetrahedron

•  Silicatemineralscrystallizefrommagmaasitcools.

•  Thetypeofmineralthatformsisaresultofthepressureandtemperatureoftheenvironmentofforma;on.

•  Example:Olivinewillcrystallizeattemperaturesofabout1200°C,undergreatpressurebelowthesurface.

•  Quartzwillcrystallizeat700°Cclosetothesurface.

•  Silicatemineralssuchasclaymineralscanformatthesurfacewhenexposedtotheelementsandbrokendown,aprocessknownasweathering.

•  Somesilicatemineralsonlyformfromthepressurecausedbytectonicplatesgrindingtogethertobuildmountains.

•  GeologistsoSenusesilicatemineralsasevidencetotellthemunderwhatcondi;onsthemineralformedunder.

•  Thisinturncanhelpgeologiststodeterminehowtheplanetlookedmillionsofyearsago.

Carbonates

•  Secondmostcommonmineralgroup.

•  Thesearemineralsthatcontaintheelementscarbon,oxygen,andoneormoremetallicelements.

•  Ex.calcite

•  Dolomite–magnesiumandcalcium

•  Thesemineralsarefoundintherockslimestoneandmarble,whichareusedheavilyinconstruc;onandbuilding.