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Geology LibreTexts

2: Minerals (Exercises)

Q2.1 Cations, anions and ionic bonding

Lithium (3) 2 in shell one and 1 in shell two It loses an electron and becomes a +1 cation
Magnesium (12) 2 in shell one, 8 in shell two and 2 in shell three It loses two electrons and becomes a +2 cation
Argon (18) 2 in shell one, 8 in shell two and 8 in shell three It is electronically stable, and does not become an ion
Chlorine (17) 2 in shell one, 8 in shell two and 7 in shell three It gains an electron and becomes a -1 anion
Beryllium (4) 2 in shell one and 2 in shell two It loses two electrons and becomes a +2 cation
Oxygen (8) 2 in shell one and 6 in shell two It gains two electrons and becomes a -2 anion
Sodium (11) 2 in shell one, 8 in shell two and 1 in shell three It loses an electron and becomes a +1 cation

 

Q2.2 Mineral groups

Name Formula Group
sphalerite ZnS sulfide
magnetite Fe3O4 oxide
pyroxene MgSiO3 silicate
anglesite PbSO4 sulfate
sylvite KCl halide
silver Ag native
fluorite CaF2 halide
ilmenite FeTiO3 oxide
siderite FeCO3 carbonate
feldspar KAlSi3O8 silicate
sulphur S native
xenotime YPO4 phosphate

Q2.3 Make a tetrahedron 

Responses will vary

Q2.4 Oxygen deprivation

Single chain silicate: 1:3 (silicon to oxygen), double chain silicate: 7:19 (or 1:2.71)

Q2.5 Ferromagnesian silicates

Mineral Formula Ferromagnesian Silicate?
olivine (Mg,Fe)2SiO4 yes
pyrite FeS2 no (it’s a sulphide, not a silicate)
plagioclase CaAl2Si2O8 no
pyroxene MgSiO3 yes
hematite Fe2O3 no (it’s an oxide, not a silicate)
orthoclase KAlSi3O8 no
quartz SiO2 no
amphibole Fe7Si8O22(OH)2 yes
muscovite K2Al4 Si6Al2O20(OH)4 no
magnetite Fe3O4 no (it’s an oxide, not a silicate)
biotite K2Fe4Al2Si6Al4O20(OH)4 yes
dolomite (Ca,Mg)CO3 no (it’s a carbonate, not a silicate)
garnet Fe2Al2Si3O12 yes
serpentine Mg3Si2O5(OH)4 yes