4.3: The Chemical Classification of Gems and Minerals
- Page ID
- 3188
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)The Chemical Classification of Gems and Minerals
Gems can be organized into classes, based on their chemistry.
Table \(\PageIndex{1}\): Classes of Gems and Minerals
Class | Description |
---|---|
Class I: Pure Elements | Metals, alloys, semi-metals, and non-metals |
Class II: Sulfides | Sulfur is the principal anion: includes tellurides and arenides |
Class III: Halides | Halogen elements are anions: F, Cl, Br |
Class IV: Oxides | Oxygen is the principal anion, includes hydroxides in which the hydroxyl radical (OH) acts as the anion |
Class V a:Carbonates | Carbonate radical (CO3) is the principal anion |
Class V b:Borates | Borate radical (BO3) and borate groups are anions |
Class VI a:Tungstates | Anions are principally WO4 |
Class VI b:Sulphates | Sulphate radical (SO4) is the principal anion |
Class VII: Phosphates | Anions are principally PO4 |
Class VIII: Silicates | Silicate groups as anions combining with other elements: includes silica SiO2 |
Class I Pure Elements
Table \(\PageIndex{2}\): Pure Elements
Class I | Pure Elements |
---|---|
Diamond | Carbon (C) |
Class II Sulfides
Table \(\PageIndex{3}\): Sulfides
Class II | Sulfides |
---|---|
Marcasite | FeS2 |
Pyrite | FeS2 |
Sphalerite | ZnS |
Class IV Oxides
Table \(\PageIndex{5}\): Oxides
Class IV | Oxides |
---|---|
Anatase | TiO2 |
Brookite | TiO2 |
Chrysoberyl | BeAl2O4 |
Corundum | Al2O3 |
Hematite | Fe2O3 |
Opal | SiO2nH2O |
Quartz | SiO2 |
Rutile | TiO2 |
Spinel | MgAl2O4 |
Class Va Carbonates
Table \(\PageIndex{6}\): Carbonates
Class Va | Carbonates |
---|---|
Aragonite | CaCO3 |
Azurite | Cu3(OH/CO3)2 |
Calcite | CaCO3 |
Cerrussite | PbCO3 |
Malachite | Cu2(OH)2CO3 |
Rhodochrosite | MnCO3 |
Smithsonite | ZnCO3 |
Class Vb Borates
Table \(\PageIndex{7}\): Borates
Class Vb | Borates |
---|---|
Hambergite | Be2(OH/BO3) |
Sinhalite | MgAl(BO4) |
Ulexite | NaCaB5O6·5H2O |
Class VIa Tungstates
Table \(\PageIndex{8}\): Tungstates
Class VIa | Tungstates |
---|---|
Scheelite | Ca(WO4) |
Class VIb Sulphates
Table \(\PageIndex{9}\): Sulphates
Class VIb | Sulphates |
---|---|
Barite | Ba(SO4) |
Class VII Phosphates
Table \(\PageIndex{10}\): Phosphates
Class VII | Phosphates |
---|---|
Amblygonite | LiAl(F,OH/PO4) |
Apatite | Ca5(F/PO4)2 |
Brazilianite | NaAl3(OH2/PO4)2 |
Turquoise | CuAl6((OH)2PO4)4·4H2O |
Class VIII Silicates
Table \(\PageIndex{11}\): Silicates
Class VIII | Silicates |
---|---|
Andalusite | Al2SiO5 |
Beryl | Be3Al2(SiO3)6 |
Iolite (Cordierite) | Mg2Al4Si5O18 |
Garnet | X3Y2Si3O12 (X = Mg, Fe or Ca) (Y = Al else Fe3+ or Cr) |
Jadeite | NaAlSi2O6 |
Nephrite | Ca2(MgFe)5(Si4O11)2 |
Topaz | Al2SiO4(FOH)2 |
Tourmaline | (Na1+, Ca2+)(Li1+, Mg2+, Al3+). (Al3+, Fe3+, Mn3+)6(BO3)3 (Si6O18) (OH)4 |
Peridot | Mg2SiO4, Fe2SiO4 |
Zircon | Zr(SiO4) |