Calomel
A valid IMA mineral species - grandfathered
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About Calomel
Formula:
[Hg2]2+Cl2
Simplified HgCl.
Colour:
Colourless, white, grayish, yellowish white, yellowish grey to ash-grey, brown; darkens upon exposure to light
Lustre:
Adamantine
Hardness:
1½ - 2
Specific Gravity:
7.15
Crystal System:
Tetragonal
Member of:
Name:
From Greek kalos = beautiful and melos = black, because it turns black when it comes into contact with ammonia. This reaction, which was already known to the alchemists centuries ago, is used as a test for mercury(I).
Unique Identifiers
Mindat ID:
869
Long-form identifier:
mindat:1:1:869:1
IMA Classification of Calomel
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
HgCl
Classification of Calomel
3.AA.30
3 : HALIDES
A : Simple halides, without H2O
A : M:X = 1:1, 2:3, 3:5, etc.
3 : HALIDES
A : Simple halides, without H2O
A : M:X = 1:1, 2:3, 3:5, etc.
9.1.8.1
9 : NORMAL HALIDES
1 : AX
9 : NORMAL HALIDES
1 : AX
8.5.2
8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
5 : Halides of Zn and Hg
8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
5 : Halides of Zn and Hg
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Clo | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Calomel
Adamantine
Transparency:
Transparent
Colour:
Colourless, white, grayish, yellowish white, yellowish grey to ash-grey, brown; darkens upon exposure to light
Streak:
Light yellowish white
Hardness:
1½ - 2 on Mohs scale
Tenacity:
Sectile
Cleavage:
Distinct/Good
{110} good but slightly uneven; {011} imperfect.
{110} good but slightly uneven; {011} imperfect.
Fracture:
Conchoidal
Density:
7.15 g/cm3 (Measured) 7.23 g/cm3 (Calculated)
Optical Data of Calomel
Type:
Uniaxial (+)
RI values:
nω = 1.973 nε = 2.656
Max. Birefringence:
δ = 0.683
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Very High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized uniaxial interference figure - the conoscopic
(convergent-light, Bertrand-lens-in) view, for a grain cut with the optic axis
centred and vertical. The coloured rings are isochromatics, computed with the
same physics as the Michel-Lévy bar above; the dark cross is the isogyre.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
Pleochroism:
Weak
Comments:
Absorption E greater than O.
Comments:
Mechanically deformed crystals may exhibit optical anomalies.
Chemistry of Calomel
Mindat Formula:
[Hg2]2+Cl2
Simplified HgCl.
Simplified HgCl.
Elements listed:
Crystallography of Calomel
Crystal System:
Tetragonal
Class (H-M):
4/mmm(4/m2/m2/m) - Ditetragonal Dipyramidal
Space Group:
I4/mmm
Cell Parameters:
a = 4.4795(5) Å, c = 10.9054(9) Å
Ratio:
a:c = 1 : 2.435
Unit Cell V:
218.83 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Crystals often tabular {001}; prismatic [001]; pyramidal; equant, especially in complex twins. Complex development often exhibited. Drusy crusts of minute crystals. Massive, earthy.
Twinning:
On {112}. As contact or interpenetrant twins often repeated and with irregular and concealed boundaries.
Crystal Structure
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Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
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View
CIF File Best | x | y | z | a | b | c
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Rotation
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0010993 | Calomel | Calos N J, Kennard C H L, Davis R L (1989) The structure of calomel, Hg2Cl2, derived from neutron powder data Zeitschrift fur Kristallographie 187 305-307 |  | 1989 | 0 | 293 | |
| 0011656 | Calomel | Wyckoff R W G (1963) Second edition. Interscience Publishers, New York, New York Crystal Structures 1 85-237 | 1963 | 0 | 293 | ||
| 0017669 | Calomel | Hylleraas E (1926) Die Anordnung der Atome in den tetragonalen Kristallen der einwertigen Quecksilberhalogenide Hg2 Cl2, Hg2 Br2, Hg2 J2. Berechnung der optischen Doppelbrechung von Hg2 Cl2. _cod_database_code 1010948 Zeitschrift fur Physik 36 859-896 | 1926 | 0 | 293 | ||
| 0017974 | Calomel | Havighurst R (1926) Parameters in crystal structure. The mercurous halides _cod_database_code 1011076 Journal of the American Chemical Society 48 2113-2130 | 1926 | 0 | 293 | ||
| 0017968 | Calomel | Havighurst R (1925) Crystal structure of the mercurous halides _cod_database_code 1011069 American Journal of Science 10 15-28 | 1925 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.170 Å | (100) |
| 4.15 Å | (75) |
| 2.067 Å | (40) |
| 2.727 Å | (30) |
| 1.962 Å | (30) |
| 1.970 Å | (16) |
| 2.824 Å | (12) |
Comments:
Synthetic.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47g : [Halogen-bearing surface weathering minerals] |
Geological Setting:
Uncommon in the secondary weathering zones of mercury deposits.
Type Occurrence of Calomel
Synonyms of Calomel
Other Language Names for Calomel
Relationship of Calomel to other Species
Member of:
Other Members of Calomel Group:
| Kuzminite | HgBr | Tet. 4/mmm(4/m2/m2/m) : I4/mmm |
| Moschelite | [Hg2]2+I2 | Tet. 4/mmm(4/m2/m2/m) : I4/mmm |
Forms a series with:
Common Associates
Associations Based on Photo Data:
| 39 photos of Calomel associated with Eglestonite | [Hg2]2+3OCl3(OH) |
| 36 photos of Calomel associated with Cinnabar | HgS |
| 26 photos of Calomel associated with Native Mercury | Hg |
| 8 photos of Calomel associated with Quartz | SiO2 |
| 5 photos of Calomel associated with Calcite | CaCO3 |
| 5 photos of Calomel associated with Terlinguaite | [Hg3]4+Hg2+Cl2O2 |
| 3 photos of Calomel associated with Rosasite | (Cu,Zn)2(CO3)(OH)2 |
| 3 photos of Calomel associated with 'Chalcedony' | SiO2 |
| 2 photos of Calomel associated with Malachite | Cu2(CO3)(OH)2 |
| 2 photos of Calomel associated with Magnesiochromite | MgCr2O4 |
Related Minerals - Strunz-mindat Grouping
| 3.AA. | Brontesite | (NH4)3PbCl5 |
| 3.AA.05 | Marshite | CuI |
| 3.AA.05 | Nantokite | CuCl |
| 3.AA.05 | 'UM1999-11:I:CuS' | Cu(I,S) |
| 3.AA.05 | Miersite | (Ag,Cu)I |
| 3.AA.10 | Tocornalite | (Ag,Hg)I (?) |
| 3.AA.10 | Iodargyrite | AgI |
| 3.AA.15 | Bromargyrite | AgBr |
| 3.AA.15 | Chlorargyrite | AgCl |
| 3.AA.20 | Sylvite | KCl |
| 3.AA.20 | Halite | NaCl |
| 3.AA.20 | Villiaumite | NaF |
| 3.AA.20 | Carobbiite | KF |
| 3.AA.20 | Griceite | LiF |
| 3.AA.25 | 'UM1998-03-Cl:Tl' | TlCl |
| 3.AA.25 | Nataliyamalikite | TlI |
| 3.AA.25 | Lafossaite | Tl(Cl,Br) |
| 3.AA.25 | Salammoniac | NH4Cl |
| 3.AA.30 | Moschelite | [Hg2]2+I2 |
| 3.AA.30 | Kuzminite | HgBr |
| 3.AA.35 | Neighborite | NaMgF3 |
| 3.AA.35 | Parascandolaite | KMgF3 |
| 3.AA.40 | Javorieite | KFeCl3 |
| 3.AA.40 | Chlorocalcite | KCaCl3 |
| 3.AA.45 | Kolarite | PbTeCl2 |
| 3.AA.50 | Radhakrishnaite | PbTe3(Cl,S)2 |
| 3.AA.55 | Challacolloite | KPb2Cl5 |
| 3.AA.60 | Hephaistosite | TlPb2Cl5 |
| 3.AA.90 | Pseudocotunnite | K2PbCl4 |
Fluorescence of Calomel
Brick-red (UV)
Other Information
Thermal Behaviour:
Thermally positive.
Health Risks:
Contains mercury - always wash hands after handling. Avoid inhaling dust when handling or breaking. Never lick or ingest.
Industrial Uses:
Ore of mercury.
Calomel in petrology
An essential component of rock names highlighted in red, an accessory component in rock names highlighted in green.
Internet Links for Calomel
mindat.org URL:
https://www.mindat.org/min-869.html
Please feel free to link to this page.
Please feel free to link to this page.
Search Engines:
External Links:
Mineral Dealers:
References for Calomel
Reference List:
Beudant, François-Sulpice (1830) Traité élémentaire de minéralogie. Deuxiéme Edition [Elementary Treatise on Mineralogy. Second Edition] (2nd ed.) Vol. 1 - Tome Premier [Volume One]. Chez Verdière. pp.500-500
Goldschmidt, V.; Mauritz, B. (1908) Über Kalomel. Zeitschrift für Kristallographie, 44 (1-6). 393-406 doi:10.1524/zkri.1908.44.1.393
Hillebrand, W.F.; Schaller, W.T. (1909) The mercury minerals from Terlingua, Texas. Bulletin 405. US Geological Survey p.1-174. doi:10.3133/b405 p.159
Nest, J. S. van (1910) Beiträge zur Kenntnis der Quecksilberhalogenide. Zeitschrift für Kristallographie, 47 (1-6). p.263-272. doi:10.1524/zkri.1910.47.1.263
Hawthorne, Frank C., Burke, Ernst A. J., Ercit, T. Scott, Grew, Edward S., Grice, Joel D., Jambor, John L., Puziewicz, Jacek, Roberts, Andrew C., Vanko, David A. (1988) New Mineral Names. American Mineralogist, 73 (1-2) 189-199
Localities for Calomel
Showing 107 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
Australia | |
| Byrnes (1993) |
Chile | |
| Oviedo et al. (1991) |
| Chouinard et al. (2005) |
China | |
| Jiansheng Qiu et al. (1994) |
Czech Republic | |
| Velebil (Dě) +4 other references |
France | |
| Palache et al. (1951) |
Germany | |
| Weiß (1990) |
| Palache et al. (1951) |
| Hartmut Hensel Collection | |
| Dreyer (1975) | |
| Arndt +1 other reference | |
| Hartmut Hensel Collection | |
| Heidtke (2001) |
| Weiß (1990) |
| Dreyer (1975) | |
| Heidtke (2001) | |
Italy | |
| Pantanelli D. (1896) |
| Orlandi et al. (2005) |
Japan | |
| - (2005) |
Kyrgyzstan | |
| Vasil'yev et al. (1982) +2 other references |
| Kolesar et al. (1993) | |
Mexico | |
| Gallagher et al. (1948) |
| Panczner (1987) | |
| Panczner (1987) |
| Percy Babb (1909) +1 other reference |
| Braith et al. (2001) |
| Clark (1993) |
Russia | |
| Vasil'yev et al. (1983) +1 other reference |
| [Der Aufschluss 1995:4 p163-180] +1 other reference |
| Seredin +1 other reference |
| Canadian Mineralogist Feb. 1999 +2 other references |
| Pekov (1998) +1 other reference |
Serbia | |
| Palache et al. (1951) |
Slovakia | |
| Koděra et al. (1986) |
| Koděra et al. (1986) |
| Koděra et al. (1986) |
Spain | |
| Rewitzer et al. (2023) |
| in Spanish version (Revista de Minerales) +1 other reference |
| Navarro et al. (2009) |
| Saupe (1990) |
| Fabre (n.d.) | |
| Sainz de Baranda Graf et al. (2019) |
| Calvo Rebollar et al. (2022) +1 other reference |
UK | |
| Encyclopedia of Mins. +2 other references |
USA | |
| Anthony et al. (1995) |
| MRDS file #10040378. |
| Orr (1990) |
| Lausen (1926) +1 other reference | |
| - (2005) |
| - (2005) | |
| - (2005) | |
| - (2005) |
| - (2005) | |
| - (2005) |
| Roberts et al. (2003) | |
| - (2005) | |
| - (2005) | |
| Mineralogical Society of America - ... | |
| - (2005) |
| - (2005) | |
| - (2005) | |
| - (2005) | |
| - (2005) | |
| - (2005) |
| Murdoch (1966) |
| Murdoch (1966) +2 other references |
| Dunning +2 other references |
| Bailey et al. (1959) |
| Rogers (1911) +2 other references |
| Rogers (1911) +1 other reference |
| Rogers (1911) +3 other references |
| Davis (1955) +3 other references | |
| Woodhouse (1934) +1 other reference | |
| Eckel et al. (1997) |
| Stewart et al. (1977) |
| Castor et al. (2004) |
| Stewart et al. (1977) | |
| USGS Open-File Report 76-56 +1 other reference |
| LaPointe et al. (199) | |
| NBMG Open File report 83-9 +1 other reference | |
| Castor et al. (2004) |
| Castor et al. (2004) | |
| Vikre (1985) +1 other reference |
| McCormack (2000) +1 other reference |
| Castor et al. (2004) |
| Castor et al. (2004) | |
| Castor et al. (2004) +1 other reference |
| USGS Bull 931-K +2 other references | |
| U.S.G.S. Bulletin 973E +1 other reference |
| Kleinhampl et al. (1984) |
| Castor et al. (2004) |
| Castor et al. (2004) | |
| Castor et al. (2004) |
| Johnson (1977) +1 other reference |
| Castor et al. (2004) | |
| Johnson (1977) | |
| Castor et al. (2004) | |
| Johnson (1977) | |
| Castor et al. (2004) +1 other reference |
| NBMG Bull 70 Geology and Mineral ... |
| Northrop et al. (1996) |
| - (2005) |
| McCormack (2000) |
| Smith (1991) |
| Smith (1991) | |
| Kelly Nash Collection | |
| Palache et al. (1951) +2 other references |
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Mariposa Mine, Brewster County, Texas, USA