Pentahydrite
A valid IMA mineral species - grandfathered
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About Pentahydrite
Formula:
MgSO4 · 5H2O
Colour:
Colourless, pale blue
Lustre:
Vitreous
Hardness:
2½
Specific Gravity:
1.896
Crystal System:
Triclinic
Member of:
Name:
In allusion to its chemical composition having five (PENTA-) molecules of water (HYDR-) in its formula.
Type Locality:
Unique Identifiers
Mindat ID:
3153
Long-form identifier:
mindat:1:1:3153:6
IMA Classification of Pentahydrite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
MgS6+O4·5H2O
Classification of Pentahydrite
7.CB.20
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
C : Sulfates (selenates, etc.) without additional anions, with H2O
B : With only medium-sized cations
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
C : Sulfates (selenates, etc.) without additional anions, with H2O
B : With only medium-sized cations
29.6.7.3
29 : HYDRATED ACID AND NORMAL SULFATES
6 : AXO4·xH2O
29 : HYDRATED ACID AND NORMAL SULFATES
6 : AXO4·xH2O
25.3.4
25 : Sulphates
3 : Sulphates of Mg
25 : Sulphates
3 : Sulphates 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 |
|---|---|---|
| Phy | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Pronunciation of Pentahydrite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Pentahydrite
Vitreous
Colour:
Colourless, pale blue
Comment:
pale blue or pale green from impurities.
Streak:
White
Hardness:
2½ on Mohs scale
Density:
1.896 g/cm3 (Measured) 1.90 g/cm3 (Calculated)
Optical Data of Pentahydrite
Type:
Biaxial (-)
RI values:
nα = 1.482 - 1.495 nβ = 1.492 - 1.512 nγ = 1.493 - 1.518
2V:
Measured: 55° , Calculated: 34°
Max. Birefringence:
δ = 0.011 - 0.023
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:
Moderate (negative)
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 Pentahydrite
Mindat Formula:
MgSO4 · 5H2O
Element Weights:
Elements listed:
Crystallography of Pentahydrite
Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Space Group:
P1
Cell Parameters:
a = 6.314(5) Å, b = 10.505(18) Å, c = 6.030(6) Å
α = 81.17°, β = 109.88°, γ = 105.1°
α = 81.17°, β = 109.88°, γ = 105.1°
Ratio:
a:b:c = 0.601 : 1 : 0.574
Unit Cell V:
362.21 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Typically as efflorescences.
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
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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) |
|---|---|---|---|---|---|---|---|
| 0004017 | Pentahydrite | Peterson R C, Hammarstrom J M, Seal R R (2006) Alpersite (Mg,Cu)SO4*7H2O, a new mineral of the melanterite group, and cuprian pentahydrite: Their occurrence within mine waste American Mineralogist 91 261-269 |  | 2006 | Miami, Arizona, USA | 0 | 293 |
| 0004016 | Pentahydrite | Peterson R C, Hammarstrom J M, Seal R R (2006) Alpersite (Mg,Cu)SO4*7H2O, a new mineral of the melanterite group, and cuprian pentahydrite: Their occurrence within mine waste American Mineralogist 91 261-269 | | 2006 | Big Mike mine, Nevada, USA | 0 | 293 |
| 0009436 | Pentahydrite | Baur W H, Rolin J L (1972) Salt hydrates. IX. The comparison of the crystal structure of magnesium sulfate pentahydrate with copper sulfate pentahydrate and magnesium chromate pentahydrate Acta Crystallographica B28 1448-1455 |  | 1972 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 4.93 Å | (100) |
| 3.26 Å | (40) |
| 5.15 Å | (30) |
| 3.65 Å | (30) |
| 2.95 Å | (30) |
| 1.995 Å | (35) |
| 2.79 Å | (25) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 45b : [Other oxidized fumarolic minerals] | |
| 47b : [Sulfates and sulfites] | |
| Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
| 48 : Soil leaching zone minerals | <0.6 |
| 50 : Coal and/or oil shale minerals | <0.36 |
| Stage 10b: Anthropogenic minerals | <10 Ka |
| 55 : Anthropogenic mine minerals |
Type Occurrence of Pentahydrite
Place of Conservation of Type Material:
No designated type material.
Synonyms of Pentahydrite
Other Language Names for Pentahydrite
Varieties of Pentahydrite
| Kellerite | A Cu-bearing variety of pentahydrite. |
Relationship of Pentahydrite to other Species
Member of:
Other Members of Chalcanthite Group:
| Belogubite | CuZn(SO4)2 · 10H2O | Tric. 1 : P1 |
| Chalcanthite | CuSO4 · 5H2O | Tric. 1 : P1 |
| Jôkokuite | MnSO4 · 5H2O | Tric. 1 : P1 |
| Siderotil | FeSO4 · 5H2O | Tric. |
Common Associates
Associations Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
| 7.CB. | Sarvodaite | Al2(SO4)3 · 5H2O |
| 7.CB.02 | Voudourisite | CdSO4 · H2O |
| 7.CB.05 | Szmikite | MnSO4 · H2O |
| 7.CB.05 | Szomolnokite | FeSO4 · H2O |
| 7.CB.05 | Cobaltkieserite | CoSO4 · H2O |
| 7.CB.05 | Dwornikite | Ni(SO4) · H2O |
| 7.CB.05 | Kieserite | MgSO4 · H2O |
| 7.CB.05 | Poitevinite | (Cu,Fe)SO4 · H2O |
| 7.CB.05 | Gunningite | ZnSO4 · H2O |
| 7.CB.07 | Sanderite | MgSO4 · 2H2O |
| 7.CB.10 | Bonattite | CuSO4 · 3H2O |
| 7.CB.12 | Belogubite | CuZn(SO4)2 · 10H2O |
| 7.CB.15 | Drobecite | CdSO4 · 4H2O |
| 7.CB.15 | Aplowite | CoSO4 · 4H2O |
| 7.CB.15 | Cranswickite | MgSO4 · 4H2O |
| 7.CB.15 | Rozenite | FeSO4 · 4H2O |
| 7.CB.15 | Starkeyite | MgSO4 · 4H2O |
| 7.CB.15 | Ilesite | Mn2+(SO4) · 4H2O |
| 7.CB.15 | Boyleite | ZnSO4 · 4H2O |
| 7.CB.20 | Siderotil | FeSO4 · 5H2O |
| 7.CB.20 | Jôkokuite | MnSO4 · 5H2O |
| 7.CB.20 | Chalcanthite | CuSO4 · 5H2O |
| 7.CB.25 | Chvaleticeite | Mn2+(H2O)6(SO4) |
| 7.CB.25 | Nickelhexahydrite | Ni2+(H2O)6(SO4) |
| 7.CB.25 | Hexahydrite | Mg(H2O)6(SO4) |
| 7.CB.25 | Bianchite | Zn(H2O)6(SO4) |
| 7.CB.25 | Moorhouseite | Co2+(H2O)6(SO4) |
| 7.CB.25 | Ferrohexahydrite | Fe2+(H2O)6(SO4) |
| 7.CB.30 | Retgersite | NiSO4 · 6H2O |
| 7.CB.35 | Zincmelanterite | Zn(H2O)6(SO4) · H2O |
| 7.CB.35 | Melanterite | Fe2+(H2O)6(SO4) · H2O |
| 7.CB.35 | Alpersite | (Mg,Cu2+)(H2O)6(SO4) · H2O |
| 7.CB.35 | Bieberite | Co2+(H2O)6(SO4) · H2O |
| 7.CB.35 | Boothite | Cu2+(H2O)6(SO4) · H2O |
| 7.CB.35 | Mallardite | Mn2+(H2O)6(SO4) · H2O |
| 7.CB.40 | Epsomite | MgSO4 · 7H2O |
| 7.CB.40 | Goslarite | ZnSO4 · 7H2O |
| 7.CB.40 | Morenosite | NiSO4 · 7H2O |
| 7.CB.45 | Meta-alunogen | Al2(SO4)3 · 12H2O |
| 7.CB.45 | Alunogen | Al2(SO4)3 · 17H2O |
| 7.CB.50 | Aluminocoquimbite | Al2Fe2(SO4)6(H2O)12 · 6H2O |
| 7.CB.50 | Lazaridisite | Cd3(SO4)3 · 8H2O |
| 7.CB.52 | Pararaisaite | CuMg[Te6+O4(OH)2] · 6H2O |
| 7.CB.55 | Paracoquimbite | Fe4(SO4)6(H2O)12 · 6H2O |
| 7.CB.55 | Rhomboclase | (H5O2)Fe3+(SO4)2 · 2H2O |
| 7.CB.55 | Raisaite | CuMg[Te6+O4(OH)2] · 6H2O |
| 7.CB.55 | Coquimbite | AlFe3(SO4)6(H2O)12 · 6H2O |
| 7.CB.57 | 'Caichengyunite' | Fe2+3Al2(SO4)6 · 30H2O |
| 7.CB.60 | Kornelite | Fe2(SO4)3 · 7H2O |
| 7.CB.65 | Quenstedtite | Fe2(SO4)3 · 11H2O |
| 7.CB.70 | Lausenite | Fe2(SO4)3 · 5H2O |
| 7.CB.75 | Römerite | Fe2+Fe3+2(SO4)4 · 14H2O |
| 7.CB.75 | Lishizhenite | ZnFe2(SO4)4 · 14H2O |
| 7.CB.80 | Ransomite | CuFe2(SO4)4 · 6H2O |
| 7.CB.85 | Dietrichite | ZnAl2(SO4)4 · 22H2O |
| 7.CB.85 | Halotrichite | Fe2+Al2(SO4)4 · 22H2O |
| 7.CB.85 | Apjohnite | Mn2+Al2(SO4)4 · 22H2O |
| 7.CB.85 | Redingtonite | Fe2+Cr3+2(SO4)4 · 22H2O |
| 7.CB.85 | Pickeringite | MgAl2(SO4)4 · 22H2O |
| 7.CB.85 | Bílinite | Fe2+Fe3+2(SO4)4 · 22H2O |
| 7.CB.85 | Wupatkiite | Co2+Al2(SO4)4 · 22H2O |
| 7.CB.90 | Meridianiite | MgSO4 · 11H2O |
Other Information
Notes:
Soluble in water
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Pentahydrite
mindat.org URL:
https://www.mindat.org/min-3153.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Pentahydrite
Reference List:
Robson, Homer Louis (1927) The system MgSO4·H2O from 68 to 240°. Journal Of The American Chemical Society, 49 (11). 2772-2783 doi:10.1021/ja01410a016
Milton, Charles, Johnston, William Drum (1938) Sulphate minerals of the Comstock Lode, Nevada. Economic Geology, 33 (7) 749-771 doi:10.2113/gsecongeo.33.7.749
Baur, W. H., Rolin, J. L. (1972) Salt hydrates. IX. The comparison of the crystal structure of magnesium sulfate pentahydrate with copper sulfate pentahydrate and magnesium chromate pentahydrate. Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry, 28 (5) 1448-1455 doi:10.1107/s0567740872004443
Localities for Pentahydrite
Showing 45 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.
Argentina | |
| Bengochea et al. (1998) |
Australia | |
| Harris et al. (2003) |
| Wilson et al. (2014) |
Austria | |
| Strasser (1989) |
| Exel (1993) |
| Exel (1993) |
Canada | |
| Last (1990) |
Chile | |
| Gerhard Möhn collection |
Costa Rica | |
| Ulloa et al. (2018) |
Czech Republic | |
| Matýsek et al. (2026) |
| Hršelová et al. (2013) |
Germany | |
| Brockt et al. (2001) |
| Witzke (1992) |
| Witzke et al. (1998) |
Greece | |
| Rieck et al. (2018) |
Hungary | |
| Mecsek-Oko |
Iceland | |
| Balić-Žunić et al. (2016) |
India | |
| Sinha et al. (2003) |
Namibia | |
| von Bezing (2007) |
| Dill et al. (2002) |
Norway | |
| Gunnar Raade (1990) |
Peru | |
| Diaby et al. (2006) |
Poland | |
| Cabała et al. (2008) |
Romania | |
| A. Januszewska PXRD data / Januszewska et al. (in preparation) |
Russia | |
| Cesnokov et al. (1998) |
| Cesnokov et al. (1998) | |
| N.V. et al. (2019) |
| Kasatkin et al. (2021) |
| Kasatkin et al. (2014) |
Senegal | |
| Montoroi (1995) |
Tunisia | |
| Smykatz-Kloss et al. (2010) |
Ukraine | |
| Nesterovskiy et al. (2015) | |
USA | |
| Quick et al. (1989) +1 other reference |
| Jeffrey Weissman collection |
| Adams et al. (2014) |
| Adams et al. (2014) |
| 87-293 +4 other references |
| Eckel et al. (1997) |
| Palache et al. (1951) |
| Econ Geol (2004) |
| Palache et al. (1951) +1 other reference |
| Milton et al. (1938) |
| Joe Marty (2015) |
| Dietrich (1990) |
Zimbabwe | |
| Frei (2005) |
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Alma Mine, Leona Heights deposit, Leona Heights, Oakland, Oakland Hills, Alameda County, California, USA