Hydromagnesite
A valid IMA mineral species - grandfathered
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About Hydromagnesite
Formula:
Mg5(CO3)4(OH)2 · 4H2O
Colour:
Colourless to white; colourless in transmitted light
Lustre:
Vitreous, Silky, Pearly, Earthy
Hardness:
3½
Specific Gravity:
2.24 - 2.25
Crystal System:
Monoclinic
Name:
Named in 1827 by Hans Gabriel Trolle-Wachmeister in allusion to the composition, being a HYDRated MAGNESium carbonate.
Type Locality:
A low-temperature hydrothermal mineral occurring in veinlets in serpentine and altered magnesium-rich igneous rocks; also as an alteration product of brucite in periclase marbles.
Lowest hydrate in a group of similar species comprising also dypingite, giorgiosite, and 'UM1973-06-CO:MgH'.
Lowest hydrate in a group of similar species comprising also dypingite, giorgiosite, and 'UM1973-06-CO:MgH'.
Unique Identifiers
Mindat ID:
1979
Long-form identifier:
mindat:1:1:1979:4
Similar Names
| Hydromagnesite (of von Kobell, 1845) | A synonym of 'Hydrodolomite' | |
| Hydromagnetite | A variety of Magnetite | Fe2+Fe23+O4 · nH2O |
IMA Classification of Hydromagnesite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Mg5(CO3)4(OH)2·4H2O
Classification of Hydromagnesite
5.DA.05
5 : CARBONATES (NITRATES)
D : Carbonates with additional anions, with H2O
A : With medium-sized cations
5 : CARBONATES (NITRATES)
D : Carbonates with additional anions, with H2O
A : With medium-sized cations
16b.7.1.1
16b : HYDRATED CARBONATES CONTAINING HYDROXYL OR HALOGEN
7 : Miscellaneous
16b : HYDRATED CARBONATES CONTAINING HYDROXYL OR HALOGEN
7 : Miscellaneous
11.3.7
11 : Carbonates
3 : Carbonates of Mg
11 : Carbonates
3 : Carbonates of Mg
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 |
|---|---|---|
| Hmgs | 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 Hydromagnesite
Vitreous, Silky, Pearly, Earthy
Transparency:
Transparent, Translucent
Comment:
silky to pearly to dull in aggregates.
Colour:
Colourless to white; colourless in transmitted light
Hardness:
3½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
On {010}.
On {010}.
Parting:
Possible parting on {100}.
Density:
2.24 - 2.25 g/cm3 (Measured) 2.25 g/cm3 (Calculated)
Optical Data of Hydromagnesite
Type:
Biaxial (+)
RI values:
nα = 1.523(3) nβ = 1.527(3) nγ = 1.545(1)
2V:
Measured: 50° , Calculated: 52°
Birefringence:
0.022
Max. Birefringence:
δ = 0.022
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:
None to Very Low
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 biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Dispersion:
none
Chemistry of Hydromagnesite
Mindat Formula:
Mg5(CO3)4(OH)2 · 4H2O
Element Weights:
Elements listed:
Crystallography of Hydromagnesite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/b
Setting:
P21/c
Cell Parameters:
a = 10.105(5) Å, b = 8.954(2) Å, c = 8.378(4) Å
β = 114.44(5)°
β = 114.44(5)°
Ratio:
a:b:c = 1.129 : 1 : 0.936
Unit Cell V:
690.12 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Crystals small, occurring as tufts, rosettes, or crusts of acicular or bladed crysta;s elongated [001] and flattened {100}. Massive, chalky.
Twinning:
Twin plane {100} and composition face {100}. Twinning very common, polysynthetic.
Comment:
pseudo-orthorhombic.
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Show
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
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Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Display Options
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
View
CIF File Best | x | y | z | a | b | c
CIF File Best | x | y | z | a | b | c
Rotation
Stop | Start
Stop | Start
Labels
Console Off | On | Grey | Yellow
Console Off | On | Grey | Yellow
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) |
|---|---|---|---|---|---|---|---|
| 0009586 | Hydromagnesite | Akao M, Iwai S (1977) The hydrogen bonding of hydromagnesite Acta Crystallographica B33 1273-1275 |  | 1977 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Loading XRD data...
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 9.20 Å | (39) |
| 6.40 Å | (38) |
| 5.79 Å | (100) |
| 4.58 Å | (7) |
| 4.46 Å | (17) |
| 4.186 Å | (31) |
| 4.090 Å | (12) |
| 4.022 Å | (8) |
| 3.856 Å | (1) |
| 3.812 Å | (13) |
| 3.503 Å | (14) |
| 3.317 Å | (28) |
| 3.207 Å | (16) |
| 3.142 Å | (20) |
| 3.101 Å | (11) |
| 3.088 Å | (10) |
| 3.063 Å | (6) |
| 2.919 Å | (11) |
| 2.899 Å | (82) |
| 2.779 Å | (7) |
| 2.692 Å | (25) |
| 2.637 Å | (5) |
| 2.556 Å | (5) |
| 2.543 Å | (4) |
| 2.529 Å | (9) |
| 2.504 Å | (20) |
| 2.478 Å | (10) |
| 2.469 Å | (10) |
| 2.442 Å | (5) |
| 2.417 Å | (7) |
| 2.387 Å | (2) |
| 2.350 Å | (14) |
| 2.298 Å | (33) |
| 2.233 Å | (4) |
| 2.207 Å | (25) |
| 2.189 Å | (11) |
| 2.186 Å | (11) |
| 2.174 Å | (7) |
| 2.161 Å | (20) |
| 2.154 Å | (25) |
| 2.146 Å | (19) |
| 2.137 Å | (12) |
| 2.093 Å | (1) |
| 2.040 Å | (6) |
| 2.025 Å | (8) |
| 2.012 Å | (5) |
| 1.994 Å | (25) |
| 1.988 Å | (19) |
| 1.974 Å | (4) |
Comments:
ICDD 25-513
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 3b: Earth’s earliest hydrosphere | >4.45 |
| 13 : Hadean serpentinization | |
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47c : [Carbonates, phosphates, borates, nitrates] | |
| Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
| 50 : Coal and/or oil shale minerals | <0.36 |
| Stage 10b: Anthropogenic minerals | <10 Ka |
| 54 : Coal and other mine fire minerals (see also #51 and #56) | |
| 55 : Anthropogenic mine minerals |
Geological Setting:
Low-temperature, hydrothermal environments in serpentine and altered magnesium-rich igneous rocks.
Type Occurrence of Hydromagnesite
Associated Minerals at Type Locality:
Synonyms of Hydromagnesite
Other Language Names for Hydromagnesite
Common Associates
Associations Based on Photo Data:
| 86 photos of Hydromagnesite associated with Artinite | Mg2(CO3)(OH)2 · 3H2O |
| 45 photos of Hydromagnesite associated with Brucite | Mg(OH)2 |
| 37 photos of Hydromagnesite associated with Aragonite | CaCO3 |
| 27 photos of Hydromagnesite associated with Callaghanite | Cu2Mg2(CO3)(OH)6 · 2H2O |
| 21 photos of Hydromagnesite associated with Serpentine Subgroup | D3[Si2O5](OH)4 |
| 21 photos of Hydromagnesite associated with Magnesite | MgCO3 |
| 20 photos of Hydromagnesite associated with Calcite | CaCO3 |
| 16 photos of Hydromagnesite associated with Dypingite | Mg5(CO3)4(OH)2 · 5H2O |
| 12 photos of Hydromagnesite associated with Lizardite | Mg3(Si2O5)(OH)4 |
| 10 photos of Hydromagnesite associated with Quartz | SiO2 |
Related Minerals - Strunz-mindat Grouping
| 5.DA. | Alexkhomyakovite | K6(Ca2Na)(CO3)5Cl · 6H2O |
| 5.DA. | Amoraite | Ca12Al6(OH)36(CO3)2(SO3) · 15H2O |
| 5.DA.05 | Dypingite | Mg5(CO3)4(OH)2 · 5H2O |
| 5.DA.05 | 'UM1986-10-CO:ClHMgMnZn (also called Mineral F, Dunn, 1995)' | Mg5(Zn,Mn)3(CO3)2(OH,Cl)12 · H2O |
| 5.DA.05 | 'UM1987-01-CO:HMgS' | Mg4(CO3)2(OH)4 · 6H2O ? |
| 5.DA.05 | Giorgiosite | Mg5(CO3)4(OH)2 · 5-6H2O |
| 5.DA.05 | Widgiemoolthalite | Ni5(CO3)4(OH)2 · 5H2O |
| 5.DA.10 | Artinite | Mg2(CO3)(OH)2 · 3H2O |
| 5.DA.10 | Chlorartinite | Mg2(CO3)(OH)Cl · 2H2O |
| 5.DA.10 | Indigirite | Mg2Al2(CO3)4(OH)2 · 15H2O |
| 5.DA.15 | Zaratite | Ni3(CO3)(OH)4 · 4H2O ? |
| 5.DA.15 | Otwayite | Ni2(CO3)(OH)2 · H2O |
| 5.DA.20 | Kambaldaite | NaNi4(CO3)3(OH)3 · 3H2O |
| 5.DA.25 | Callaghanite | Cu2Mg2(CO3)(OH)6 · 2H2O |
| 5.DA.30 | Claraite | (Cu,Zn)15(CO3)4(AsO4)2(SO4)(OH)14 · 7H2O |
| 5.DA.35 | Hydroscarbroite | Al14(CO3)3(OH)36 · nH2O |
| 5.DA.35 | Scarbroite | Al5(CO3)(OH)13 · 5H2O |
| 5.DA.40 | Karchevskyite | Mg18Al9(OH)54Sr2(CO3)9(H2O)6(H3O)5 |
| 5.DA.40 | 'UM1987-05-OH:AlCMg' | Mg4Al2(OH)12(CO3,SO4) · 3H2O |
| 5.DA.40 | Quintinite | Mg4Al2(OH)12(CO3) · 3H2O |
| 5.DA.40 | Charmarite | Mn2+4Al2(OH)12[CO3] · 3H2O |
| 5.DA.40 | Caresite | Fe2+4Al2(OH)12[CO3] · 3H2O |
| 5.DA.45 | 'Hydrotalcite-2H' | Mg6Al2(CO3)(OH)16 · 4H2O |
| 5.DA.45 | 'Stichtite-2H' | Mg6(Cr,Al)2(CO3)(OH)16 · 4H2O |
| 5.DA.45 | Brugnatellite | Mg6Fe3+(CO3)(OH)13 · 4H2O |
| 5.DA.45 | Zaccagnaite | Zn4Al2(OH)12[CO3] · 3H2O |
| 5.DA.45 | 'Pyroaurite-2H' | Mg6Fe3+2(OH)16(CO3) · 4H2O |
| 5.DA.45 | Liudongshengite | Zn4Cr2(OH)12(CO3) · 3H2O |
| 5.DA.45 | Chlormagaluminite | Mg4Al2(OH)12Cl2 · 3H2O |
| 5.DA.50 | Pyroaurite | Mg6Fe3+2(OH)16[CO3] · 4H2O |
| 5.DA.50 | Takovite | Ni6Al2(OH)16[CO3] · 4H2O |
| 5.DA.50 | Reevesite | Ni6Fe3+2(OH)16(CO3) · 4H2O |
| 5.DA.50 | Kaznakhtite | Ni6Co3+2(CO3)(OH)16 · 4H2O |
| 5.DA.50 | Comblainite | Ni4Co2(OH)12[CO3] · 3H2O |
| 5.DA.50 | Marioantofilliite | [Cu4Al2(OH)12](CO3) · 3H2O |
| 5.DA.50 | Hydrotalcite | Mg6Al2(CO3)(OH)16 · 4H2O |
| 5.DA.50 | Stichtite | Mg6Cr3+2(OH)16[CO3] · 4H2O |
| 5.DA.50 | Desautelsite | Mg6Mn3+2(OH)16[CO3] · 4H2O |
| 5.DA.55 | Coalingite | Mg10Fe3+2(OH)24[CO3] · 2H2O |
| 5.DA.55 | Akopovaite | Al4Li2(OH)12(CO3)(H2O)3 |
| 5.DA.60 | Šlikite | Zn2Mg(CO3)2(OH)2 · 4H2O |
| 5.DA.65 | Marklite | Cu5(CO3)2(OH)6 · 6H2O |
Fluorescence of Hydromagnesite
Sometimes fluorescent.
Other Information
Thermal Behaviour:
Before the blowpipe, infusible, but whitens and gives an alkaline reaction (ex. with tumeric paper).
In a closed tube gives off water and carbon dioxide.
In a closed tube gives off water and carbon dioxide.
Notes:
Soluble in acids. The process may be slow in cold acids but in hot acid it may be fast, with effervescence.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Industrial Uses:
None.
Internet Links for Hydromagnesite
mindat.org URL:
https://www.mindat.org/min-1979.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Hydromagnesite
Reference List:
Silliman Jr., Benjamin (1850) [Lancasterite]. American Journal of Science: 9: 216 (as Lancasterite).
Larsen, Esper S. (1921) The microscopic determination of the nonopaque minerals. Bulletin 679. US Geological Survey doi:10.3133/b679 p.89
Cummings, J. M. (1940) Saline and Hydromagnesite Deposits of British Columbia. Bulletin 4. British Columbia Department of Mines
Caillère, Simonne (1943) Contribution à l'étude de l'hydromagnésite et de quelques autres hydrocarbonates magnésiens : l'hydrogiobertite, l'hydrodolomite et la giorgiosite. Bulletin de la Société française de Minéralogie, 66 (1). 55-70 doi:10.3406/bulmi.1943.4525
Davies, Peter J., Bubela, B. (1973) The transformation of nesquehonite into hydromagnesite. Chemical Geology, 12 (4) 289-300 doi:10.1016/0009-2541(73)90006-5
Akao, M., Marumo, F., Iwai, S. (1974) The crystal structure of hydromagnesite. Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry, 30 (11) 2670-2672 doi:10.1107/s0567740874007771
Akao, M., Iwai, S. (1977) The hydrogen bonding of hydromagnesite. Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry, 33 (4) 1273-1275 doi:10.1107/s0567740877005834
Localities for Hydromagnesite
Showing 426 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.
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Miola, Predazzo, Trento Province, Trentino-Alto Adige/Südtirol, Italy