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The Mineralogy of Caesium

General Properties
Other names:Also known as cesium, primarily in the United States.
Atomic Number:55
Standard atomic weight (Ar):132.9054519(2)
Electron configuration:[Xe] 6s1
Five different photos of the same vial with 1 gram of caesium
Atomic Properties
Electronegativity (Pauling scale):0.79
Atomic Radius:298 pm
Ionic Radius:167 pm (+1)
1st Ionization energy:376 kJ/mol
1st Electron affinity:-46 kJ/mol
Oxidation States:1
Physical Properties
Standard State:solid
Bonding Type:metallic
Melting Point:302 K
Boiling Point:944 K
Density:1.88 g/cm3
Metal/Non-Metal:alkali metal
Main isotopes of Caesium
Isotope% in NatureHalf LifeDecay typeDecay product
133Cs100%-Spontaneous fission ?
Main ions of Caesium
NameIonExample minerals
Other Information
Year Discovered:1860
Discovered By:
Robert Bunsen and Gustav Kirchhoff
Year Isolated:1882
Isolated By:
Carl Setterberg
Named For:From Latin: caesius - "sky blue"
CPK color coding:#57178F
External Links:WikipediaWebElementsLos Alamos National LaboratoryTheodore Gray's
Simple Compounds
Sulfidesdicaesium sulphideCs2S+1
dicaesium disulphideCs2S2+1
dicaesium trisulphideCs2S3+1
dicaesium hexasulphideCs2S6+1
dicaesium tetrasulphideCs2S4+1
dicaesium pentasulphideCs2S5+1
dicaesium heptasulphideCs2S7+1
Selenidesdicaesium selenideCs2Se+1
Telluridesdicaesium tellurideCs2Te+1
Hydridescaesium hydrideCsH+1
Fluoridescaesium fluorideCsF+1
Chloridescaesium chlorideCsCl+1
Iodidescaesium iodideCsI+1
Oxidesdicaesium oxideCs2O+1
caesium superoxideCsO2+1
dicaesium peroxideCs2O2+1
Caesium as a chromophore in minerals and gems
Cs+Does NOT cause colour as it has no electrons in d-orbitals. Minerals where Cs was previously thought to be a colouring agent probably contain other ions such as Mn#2+#.
Mineral Diversity of Caesium
2. Sulfides And Sulfosalts 2 valid mineral species
4. Oxides 3 valid mineral species
6. Borates2 valid mineral species
8. Phosphates, Arsenates, Vanadates2 valid mineral species
9. Silicates 9 valid mineral species
Total:18 valid species containing essential Caesium
Geochemistry of Caesium
Goldschmidt classification:Lithophile
Cs+ enters later phases in igneous rocks due to its large size.
Elemental Abundance for Caesium
Crust (CRC Handbook)3 x 10-6mass fraction, kg/kg
Crust (Kaye & Laby)1.6 x 10-6mass fraction, kg/kg
Crust (Greenwood)2.6 x 10-6mass fraction, kg/kg
Crust (Ahrens/Taylor)1.000 x 10-6mass fraction, kg/kg
Crust (Ahrens/Wänke)1.310 x 10-6mass fraction, kg/kg
Upper Crust (Ahrens/Taylor)3.700 x 10-6mass fraction, kg/kg
Sea Water (CRC Handbook)3 x 10-10mass per volume fraction, kg/L
Sea Water (Kaye & Laby)3.0 x 10-10mass per volume fraction, kg/L
Solar System (Kaye & Laby)3.7 x 10-7atom mole fraction relative to Si=1
Solar System (Ahrens)3.72 x 10-7 (5.6%)atom mole fraction relative to Si=1 (% uncertainty)
Element association of Caesium in the Mineral World
This table compares the known valid mineral species listed listed with Caesium and the other elements listed based on the official IMA formula. Note that unlike other sections on this page this includes non-essential elements.

The first data column contains the total number of minerals listed with Caesium and the element listed for that row.

The second data column lists this number as a percentage of all minerals listed with Caesium.

The final data column compares this percentage against the percentage of all minerals that contain the element listed in each row.

Click on a heading to sort.
ElementValid Minerals listed with element and Caesium% of Cs mineralsRelative to % in all minerals
Oxygen21 minerals with Cs and O87.50%14.84% higher
Hydrogen13 minerals with Cs and H54.17%0.93% higher
Silicon13 minerals with Cs and Si54.17%95.59% higher
Fluorine9 minerals with Cs and F37.50%351.17% higher
Potassium9 minerals with Cs and K37.50%288.07% higher
Sodium8 minerals with Cs and Na33.33%76.54% higher
Aluminium7 minerals with Cs and Al29.17%47.25% higher
Calcium6 minerals with Cs and Ca25.00%1.85% higher
Boron6 minerals with Cs and B25.00%392.88% higher
Beryllium5 minerals with Cs and Be20.83%837.85% higher
Iron4 minerals with Cs and Fe16.67%26.80% lower
Lithium3 minerals with Cs and Li12.50%458.06% higher
Lead2 minerals with Cs and Pb8.33%12.76% lower
Arsenic2 minerals with Cs and As8.33%26.68% lower
Antimony2 minerals with Cs and Sb8.33%70.52% higher
Zirconium2 minerals with Cs and Zr8.33%246.28% higher
Sulfur2 minerals with Cs and S8.33%57.25% lower
Titanium2 minerals with Cs and Ti8.33%21.01% higher
Niobium1 mineral with Cs and Nb4.17%23.67% higher
Rubidium1 mineral with Cs and Rb4.17%4,401.67% higher
Zinc1 mineral with Cs and Zn4.17%21.85% lower
Copper1 mineral with Cs and Cu4.17%66.65% lower
Manganese1 mineral with Cs and Mn4.17%63.87% lower
Vanadium1 mineral with Cs and V4.17%0.93% higher
Cerium1 mineral with Cs and Ce4.17%26.45% higher
Neodymium1 mineral with Cs and Nd4.17%332.85% higher
Tantalum1 mineral with Cs and Ta4.17%208.33% higher
Tungsten1 mineral with Cs and W4.17%448.98% higher
Mercury1 mineral with Cs and Hg4.17%142.03% higher
Thallium1 mineral with Cs and Tl4.17%268.99% higher
Phosphorus1 mineral with Cs and P4.17%62.17% lower
Uranium1 mineral with Cs and U4.17%12.76% lower
Periodic Table
1H 2He
3Li 4Be 5B 6C 7N 8O 9F 10Ne
11Na 12Mg 13Al 14Si 15P 16S 17Cl 18Ar
19K 20Ca 21Sc 22Ti 23V 24Cr 25Mn 26Fe 27Co 28Ni 29Cu 30Zn 31Ga 32Ge 33As 34Se 35Br 36Kr
37Rb 38Sr 39Y 40Zr 41Nb 42Mo 43Tc 44Ru 45Rh 46Pd 47Ag 48Cd 49In 50Sn 51Sb 52Te 53I 54Xe
55Cs 56Ba 57La 72Hf 73Ta 74W 75Re 76Os 77Ir 78Pt 79Au 80Hg 81Tl 82Pb 83Bi 84Po 85At 86Rn
87Fr 88Ra 89Ac 104Rd 105Db 106Sg 107Bh 108Hs 109Mt 110Ds 111Rg 112Cn 113Nh 114Fl 115Mc 116Lv 117Ts 118Og
58Ce 59Pr 60Nd 61Pm 62Sm 63Eu 64Gd 65Tb 66Dy 67Ho 68Er 69Tm 70Yb 71Lu
90Th 91Pa 92U 93Np 94Pu 95Am 96Cm 97Bk 98Cf 99Es 100Fm 101Md 102No 103Lr
Default Categories CPK Electronegativity Atomic Radius Lowest Oxidation Highest Oxidation Crustal Abundance Goldschmidt Mineral Species Minerals with Cs Relative Frequency
Xenon << Caesium >> Barium

Most widespread minerals containing Caesium
This list of minerals containing Caesium is built from the locality database. This is based on the number of localities entered for mineral species and is therefore slanted towards minerals interesting to collectors with less coverage of common rock-forming-minerals so it does not give an undistorted distribution of Caesium mineral species. It is more useful when comparing rare species rather than common species.
NameFormulaCrystal SystemMindat Localities
Pollucite(Cs,Na)2(Al2Si4O12) · 2H2OIsometric135
Ramanite-(Cs)Cs[B5O6(OH)4] · 2H2OMonoclinic3
Margaritasite(Cs,K,H3O)2(UO2)2(VO4)2 · H2OMonoclinic2

Localities with greatest number of different Caesium mineral species
map should go here
1Dara-i-Pioz Glacier (Dara-Pioz), Alai Range (Alayskiy), Tien Shan Mtn, Region of Republican Subordination, Tajikistan9 Cs minerals
Stargazer Claim, O'Grady Lake area, Northwest Territories, Canada3 Cs minerals
3Pegmatite no. 31 (Xikeng Mine; Xiyuantou), Nanping pegmatite field (Xikeng pegmatite field), Yanping District, Nanping Prefecture, Fujian Province, China2 Cs minerals
4Pakeagama Lake pegmatite, Pakeagama Lake Area, Kenora District, Ontario, Canada2 Cs minerals
5Separation Rapids Lithium Project (Separation Lake area), Kenora District, Ontario, Canada2 Cs minerals
Malkhan pegmatite field (Malchan; "Malechansk"), Krasnyi Chikoy, Chitinskaya Oblast', Transbaikalia (Zabaykalye), Eastern-Siberian Region, Russia2 Cs minerals
7Mawi pegmatite, Nilaw-Kolum pegmatite field, Du Ab District, Nuristan Province (Nurestan Province; Nooristan Province; Nuristan), Afghanistan2 Cs minerals
Antsongombato gem mine, FKT Antsentsindrano, Andrembesoa Commune, Betafo District, Vakinankaratra Region, Antananarivo Province, Madagascar2 Cs minerals

Spotted a mistake/omission? - These pages are a work in progress, so please send all comments/corrections to Thank you.

Constants and physical property data from:

David R. Lide (ed.), CRC Handbook of Chemistry and Physics, 85th Edition. CRC Press. Boca Raton, Florida (2005).
Kaye and Laby Tables of Physical & Chemical Constants (2005). Section 3.1.3, Abundances of the elements
A. Earnshaw, N. Greenwood, Chemistry of the Elements, 2nd edition, Butterworth-Heinemann, (1997)
Thomas J. Ahrens (ed.), Global Earth Physics : A Handbook of Physical Constants, American Geophysical Union (1995)
L.B. Railsback, An Earth Scientist's Periodic Table of the Elements and Their Ions : Geology 31:9 p737-740 (2003)
Emsley, J. Nature's Building Blocks: An A-Z Guide to the Elements. New York: Oxford University Press (2001)
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