Systematic MineralogySystematic Mineralogy Description of how minerals are Description of how minerals are
divided into groupsdivided into groups Groups based on anionsGroups based on anions
Single anion (ClSingle anion (Cl--)) Anion group (SiOAnion group (SiO44
4-4-))
Further divided based on structuresFurther divided based on structures
DivisionsDivisions
Class (anion division)Class (anion division) Family (structural division – silicates Family (structural division – silicates
mostly)mostly) Group (structural division)Group (structural division) Series (solid solution)Series (solid solution) Species (individual minerals)Species (individual minerals) Varieties (substituted elements)Varieties (substituted elements)
ExampleExample
Ca-grunerite:Ca-grunerite: A Ca-rich A Ca-rich varietyvariety Of a mineral Of a mineral speciesspecies In the cummingtonite-grunerite In the cummingtonite-grunerite seriesseries Of the amphibole Of the amphibole groupgroup Of the inosilicate Of the inosilicate familyfamily Of the silicate Of the silicate classclass
Mineral classMineral class Anion or anion Anion or anion gpgp
Native Native elementselements
N/AN/A
OxidesOxides OO2-2-
HydroxidesHydroxides OHOH--
HalidesHalides ClCl--, Br, Br--, F, F--
SulfidesSulfides SS2-2-
SulfatesSulfates SOSO442-2-
CarbonatesCarbonates COCO332-2-
PhosphatesPhosphates POPO443-3-
SilicatesSilicates SiOSiO444-4-
SilicatesSilicates
The most common group of minerals The most common group of minerals forming Earth’s crustforming Earth’s crust 25% of all minerals (~1000)25% of all minerals (~1000) 40% of rock forming minerals40% of rock forming minerals 90% of earth’s crust – i.e., those 90% of earth’s crust – i.e., those
minerals you are likely to findminerals you are likely to find
Silicate StructureSilicate Structure
Basic building block: silica Basic building block: silica tetrahedrontetrahedron
SiSi4+4+ with four O with four O2-2- surrounding it surrounding it Net charge is 4-Net charge is 4- Mesodesmic, polymerizationMesodesmic, polymerization
Tetrahedron can share oxygen atomsTetrahedron can share oxygen atoms
Fig. 11-1Fig. 11-1
Silica Tetrahedron
Six groups of silicate Six groups of silicate mineralsminerals
Orthosilicates = NesosilicatesOrthosilicates = Nesosilicates Single tetrahedronSingle tetrahedron
Disilicates = SorosilicatesDisilicates = Sorosilicates Two tetrahedrons share single oxygenTwo tetrahedrons share single oxygen
Ring silicates = CyclosilicatesRing silicates = Cyclosilicates 4, 5, or 6 tetrahedron share two oxygen4, 5, or 6 tetrahedron share two oxygen
Chain silicates = InosilicatesChain silicates = Inosilicates 2 or 3 oxygen shared, arranged in single 2 or 3 oxygen shared, arranged in single
or double chainor double chain Sheet silicates = PhyllosilicatesSheet silicates = Phyllosilicates
3 oxygen shared in sheets3 oxygen shared in sheets Framework silicates = TectosilicatesFramework silicates = Tectosilicates
All 4 oxygen are sharedAll 4 oxygen are shared
Fig. 11-2Fig. 11-2
Ortho-Ortho-(Neso)(Neso)Di-Di-(Soro)(Soro)
RingRing(Cyclo)(Cyclo)
Chain – Chain – double double and and singlesingle(Ino)(Ino)
Framework(Tecto)SheetSheet
(Phyllo)(Phyllo)
Z/O ratiosZ/O ratios
Z = Si tetrahedral sitesZ = Si tetrahedral sites Can be other cations, most commonly AlCan be other cations, most commonly Al
Z/O ratio depends on type of silicateZ/O ratio depends on type of silicate Ortho = 1/4Ortho = 1/4 Di = 2/7Di = 2/7 Ring = 1/3Ring = 1/3 Chain, single = 1/3; double = 4/11Chain, single = 1/3; double = 4/11 Sheet = 2/5Sheet = 2/5 Framework = 1/2Framework = 1/2
Other ionsOther ions
Quartz (and polymorphs) only Quartz (and polymorphs) only minerals with only Si and Ominerals with only Si and O
All other silicates are charge All other silicates are charge balanced by other cationsbalanced by other cations ““glue” that holds together silica glue” that holds together silica
tetrahedrontetrahedron
Degree of polymerization depends on Degree of polymerization depends on availability of Siavailability of Si Quartz and feldspars (framework): Si-Quartz and feldspars (framework): Si-
rich environmentsrich environments Si/O = ½Si/O = ½
Olivine (orthosilicate): Si-poor Olivine (orthosilicate): Si-poor environmentenvironment
Si/O = ¼Si/O = ¼
Mafic vs FelsicMafic vs Felsic
MaficMafic – rich in – rich in MaMagnesium and Iron gnesium and Iron ((FeFerrum), Si-poorrrum), Si-poor E.g. biotite, amphiboles, pyroxenes, and E.g. biotite, amphiboles, pyroxenes, and
olivineolivine Commonly dark colored Commonly dark colored
FelsicFelsic – rich in Si and Al – rich in Si and Al E.g. E.g. FeFeldspars, Quartz (ldspars, Quartz (SiSiOO22), muscovite, ), muscovite,
feldspathoidsfeldspathoids Commonly light coloredCommonly light colored
