Systematic MineralogyDescription of how minerals are divided into groupsGroups based on anionsSingle anion (Cl-)Anion group (SiO44-)Further divided based on structures

DivisionsClass (anion division)Family (structural division silicates mostly)Group (structural division)Series (solid solution)Species (individual minerals)Varieties (substituted elements)

ExampleCa-grunerite:A Ca-rich varietyOf a mineral speciesIn the cummingtonite-grunerite seriesOf the amphibole groupOf the inosilicate familyOf the silicate class

Mineral classAnion or anion gpNative elementsN/AOxidesO2-HydroxidesOH-HalidesCl-, Br-, F-SulfidesS2-SulfatesSO42-CarbonatesCO32-PhosphatesPO43-SilicatesSiO44-

SilicatesThe most common group of minerals forming Earths crust25% of all minerals (~1000)40% of rock forming minerals90% of earths crust i.e., those minerals you are likely to find

Silicate StructureBasic building block: silica tetrahedronSi4+ with four O2- surrounding itNet charge is 4-Mesodesmic, polymerizationTetrahedron can share oxygen atoms

Fig. 11-1Silica Tetrahedron

Six groups of silicate mineralsOrthosilicates = NesosilicatesSingle tetrahedronDisilicates = SorosilicatesTwo tetrahedrons share single oxygenRing silicates = Cyclosilicates4, 5, or 6 tetrahedron share two oxygen

Chain silicates = Inosilicates2 or 3 oxygen shared, arranged in single or double chainSheet silicates = Phyllosilicates3 oxygen shared in sheetsFramework silicates = TectosilicatesAll 4 oxygen are shared

Fig. 11-2Ortho-(Neso)Di-(Soro)Ring(Cyclo)Chain double and single(Ino)Framework(Tecto)Sheet(Phyllo)

Z/O ratiosZ = Si tetrahedral sitesCan be other cations, most commonly AlZ/O ratio depends on type of silicateOrtho = 1/4Di = 2/7Ring = 1/3Chain, single = 1/3; double = 4/11Sheet = 2/5Framework = 1/2

Other ionsQuartz (and polymorphs) only minerals with only Si and OAll other silicates are charge balanced by other cationsglue that holds together silica tetrahedron

Degree of polymerization depends on availability of SiQuartz and feldspars (framework): Si-rich environmentsSi/O = Olivine (orthosilicate): Si-poor environmentSi/O =

Mafic vs FelsicMafic rich in Magnesium and Iron (Ferrum), Si-poorE.g. biotite, amphiboles, pyroxenes, and olivineCommonly dark colored Felsic rich in Si and AlE.g. Feldspars, Quartz (SiO2), muscovite, feldspathoidsCommonly light colored

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