Hexahydrite
A valid IMA mineral species - grandfathered
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About Hexahydrite
Formula:
MgSO4 · 6H2O
Colour:
Colourless, white, pale greenish white; colourless in transmitted light.
Lustre:
Sub-Vitreous, Pearly, Dull, Earthy
Hardness:
2 - 2½
Specific Gravity:
1.757
Crystal System:
Monoclinic
Member of:
Name:
Named in 1911 by Robert Angus Alister Johnston in allusion to its composition, having six (HEXA-) molecules of water (HYDR-) in its formula.
Unique Identifiers
Mindat ID:
1891
Long-form identifier:
mindat:1:1:1891:9
GUID
(UUID V4):
(UUID V4):
6a2650aa-e6ab-40e4-b1f7-2df4fe6fd5db
Classification of Hexahydrite
Approved, 'Grandfathered' (first described prior to 1959)
First published:
1911
Type description reference:
7.CB.25
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
29.6.8.1
29 : HYDRATED ACID AND NORMAL SULFATES
6 : AXO4·xH2O
29 : HYDRATED ACID AND NORMAL SULFATES
6 : AXO4·xH2O
25.3.5
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 |
---|---|---|
Hhy | 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 Hexahydrite
Pronunciation:
Play | Recorded by | Country |
---|---|---|
Jolyon & Katya Ralph | United Kingdom |
Physical Properties of Hexahydrite
Sub-Vitreous, Pearly, Dull, Earthy
Transparency:
Transparent, Translucent
Colour:
Colourless, white, pale greenish white; colourless in transmitted light.
Streak:
White
Hardness:
2 - 2½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
On {100}, perfect.
On {100}, perfect.
Fracture:
Conchoidal
Density:
1.757 g/cm3 (Measured) 1.745 g/cm3 (Calculated)
Optical Data of Hexahydrite
Type:
Biaxial (-)
RI values:
nα = 1.426 nβ = 1.453 nγ = 1.456
2V:
Measured: 38° , Calculated: 36°
Max Birefringence:
δ = 0.030
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
Moderate
Dispersion:
none
Optical Extinction:
Y = b; X ∧ c = 25°.
Chemical Properties of Hexahydrite
Formula:
MgSO4 · 6H2O
IMA Formula:
Mg(SO4) · 6H2O
Elements listed:
Crystallography of Hexahydrite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P2/m
Cell Parameters:
a = 24.44 Å, b = 7.21 Å, c = 10.11 Å
β = 98.28°
β = 98.28°
Ratio:
a:b:c = 3.39 : 1 : 1.402
Unit Cell V:
1,762.94 ų (Calculated from Unit Cell)
Morphology:
Good crystals rare; sometimes thick tabular {001}. Also coarse columnar to delicately fibrous to acicular.
Twinning:
1. On {001}; 2. on {110}.
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
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Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
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View
CIF File Best | x | y | z | a | b | c
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Rotation
Stop | Start
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Labels
Console Off | On | Grey | Yellow
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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) |
---|---|---|---|---|---|---|---|
0009280 | Hexahydrite | Zalkin A, Ruben H, Templeton D H (1964) The crystal structure and hydrogen bonding of magnesium sulfate hexahydrate Acta Crystallographica 17 235-240 | 1964 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Image Loading
Radiation - Copper Kα
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
d-spacing | Intensity |
---|---|
5.45 Å | (50) |
5.10 Å | (45) |
4.88 Å | (30) |
4.39 Å | (100) |
4.16 Å | (35) |
4.04 Å | (45) |
2.94 Å | (30) |
Comments:
ICDD 24-719
Geological Environment
Paragenetic Mode(s):
Paragenetic Mode | Earliest Age (Ga) |
---|---|
Stage 2: Planetesimal differentiation and alteration | 4.566-4.550 |
6 : Secondary asteroid phases | 4.566-4.560 |
Near-surface Processes | |
21 : Chemically precipitated carbonate, phosphate, iron formations | |
25 : Evaporites (prebiotic) | |
Stage 7: Great Oxidation Event | <2.4 |
45b : [Other oxidized fumarolic minerals] | |
Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
49 : Oxic cellular biomineralization (see also #44) | <0.54 |
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 |
Type Occurrence of Hexahydrite
General Appearance of Type Material:
Seams (to about 1 cm thick) and scattered patches in altered rock. A somewhat coarse columnar structure or sometimes delictae fibrous. No distinct crystals observed.
Place of Conservation of Type Material:
No designated type specimen.
Reference:
Johnston, R.A.A. (1911) Hexahydrite, a new mineral. Summary Report of the Geological Survey Branch of the Department of Mines For the Calendar Year 1910: 26: 256-257.
Other Language Names for Hexahydrite
Relationship of Hexahydrite to other Species
Member of:
Other Members of this group:
Bianchite | Zn(SO4) · 6H2O | Mon. 2/m : P2/m |
Chvaleticeite | Mn(SO4) · 6H2O | Mon. 2/m : B2/b |
Ferrohexahydrite | FeSO4 · 6H2O | Mon. 2/m : B2/b |
Moorhouseite | Co(SO4) · 6H2O | Mon. 2/m : B2/b |
Nickelhexahydrite | Ni(SO4) · 6H2O | Mon. 2/m : B2/b |
Common Associates
Associated Minerals Based on Photo Data:
7 photos of Hexahydrite associated with Epsomite | MgSO4 · 7H2O |
6 photos of Hexahydrite associated with Betpakdalite-NaCa | [Na2(H2O)17Ca(H2O)6][Mo6+8As5+2Fe3+3O34(OH)3] |
6 photos of Hexahydrite associated with Bandylite | Cu[B(OH)4]Cl |
6 photos of Hexahydrite associated with Blödite | Na2Mg(SO4)2 · 4H2O |
6 photos of Hexahydrite associated with Nitratine | NaNO3 |
5 photos of Hexahydrite associated with Pickeringite | MgAl2(SO4)4 · 22H2O |
4 photos of Hexahydrite associated with Sulphur | S8 |
4 photos of Hexahydrite associated with Aubertite | CuAl(SO4)2Cl · 14H2O |
3 photos of Hexahydrite associated with Metavoltine | K2Na6Fe2+Fe3+6O2(SO4)12 · 18H2O |
2 photos of Hexahydrite associated with Tschermigite | (NH4)Al(SO4)2 · 12H2O |
Related Minerals - Strunz-mindat Grouping
7.CB.02 | Voudourisite | CdSO4 · H2O |
7.CB.05 | Dwornikite | Ni(SO4) · H2O |
7.CB.05 | Gunningite | ZnSO4 · H2O |
7.CB.05 | Kieserite | MgSO4 · H2O |
7.CB.05 | Poitevinite | (Cu,Fe)SO4 · H2O |
7.CB.05 | Szmikite | MnSO4 · H2O |
7.CB.05 | Szomolnokite | FeSO4 · H2O |
7.CB.05 | Cobaltkieserite | CoSO4 · H2O |
7.CB.07 | Sanderite | MgSO4 · 2H2O |
7.CB.10 | Bonattite | CuSO4 · 3H2O |
7.CB.12 | Belogubite | CuZn(SO4)2 · 10H2O |
7.CB.15 | Aplowite | (Co,Mn,Ni)SO4 · 4H2O |
7.CB.15 | Boyleite | (Zn,Mg)SO4 · 4H2O |
7.CB.15 | Ilesite | (Mn,Zn,Fe)SO4 · 4H2O |
7.CB.15 | Rozenite | FeSO4 · 4H2O |
7.CB.15 | Starkeyite | MgSO4 · 4H2O |
7.CB.15 | Drobecite | CdSO4 · 4H2O |
7.CB.15 | Cranswickite | MgSO4 · 4H2O |
7.CB.20 | Chalcanthite | CuSO4 · 5H2O |
7.CB.20 | Jôkokuite | MnSO4 · 5H2O |
7.CB.20 | Pentahydrite | MgSO4 · 5H2O |
7.CB.20 | Siderotil | FeSO4 · 5H2O |
7.CB.25 | Bianchite | Zn(SO4) · 6H2O |
7.CB.25 | Chvaleticeite | Mn(SO4) · 6H2O |
7.CB.25 | Ferrohexahydrite | FeSO4 · 6H2O |
7.CB.25 | Moorhouseite | Co(SO4) · 6H2O |
7.CB.25 | Nickelhexahydrite | Ni(SO4) · 6H2O |
7.CB.30 | Retgersite | NiSO4 · 6H2O |
7.CB.35 | Bieberite | CoSO4 · 7H2O |
7.CB.35 | Boothite | CuSO4 · 7H2O |
7.CB.35 | Mallardite | MnSO4 · 7H2O |
7.CB.35 | Melanterite | Fe2+(H2O)6SO4 · H2O |
7.CB.35 | Zincmelanterite | (Zn,Cu,Fe)SO4 · 7H2O |
7.CB.35 | Alpersite | (Mg,Cu)(SO4) · 7H2O |
7.CB.40 | Epsomite | MgSO4 · 7H2O |
7.CB.40 | Goslarite | ZnSO4 · 7H2O |
7.CB.40 | Morenosite | NiSO4 · 7H2O |
7.CB.45 | Alunogen | Al2(SO4)3 · 17H2O |
7.CB.45 | Meta-alunogen | Al2(SO4)3 · 12H2O |
7.CB.50 | Aluminocoquimbite | Al2Fe2(SO4)6(H2O)12 · 6H2O |
7.CB.50 | Lazaridisite | 3CdSO4 · 8H2O |
7.CB.52 | Pararaisaite | CuMg[Te6+O4(OH)2] · 6H2O |
7.CB.55 | Coquimbite | AlFe3(SO4)6(H2O)12 · 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.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 | Lishizhenite | ZnFe2(SO4)4 · 14H2O |
7.CB.75 | Römerite | Fe2+Fe3+2(SO4)4 · 14H2O |
7.CB.80 | Ransomite | CuFe2(SO4)4 · 6H2O |
7.CB.85 | Apjohnite | Mn2+Al2(SO4)4 · 22H2O |
7.CB.85 | Bílinite | Fe2+Fe3+2(SO4)4 · 22H2O |
7.CB.85 | Dietrichite | (Zn,Fe2+,Mn2+)Al2(SO4)4 · 22H2O |
7.CB.85 | Halotrichite | FeAl2(SO4)4 · 22H2O |
7.CB.85 | Pickeringite | MgAl2(SO4)4 · 22H2O |
7.CB.85 | Redingtonite | (Fe2+,Mg,Ni)(Cr,Al)2(SO4)4 · 22H2O |
7.CB.85 | Wupatkiite | (Co,Mg,Ni)Al2(SO4)4 · 22H2O |
7.CB.90 | Meridianiite | MgSO4 · 11H2O |
Fluorescence of Hexahydrite
Fluoresces and phosphoresces dull cream white (Sterling Mine, Ogdensburg, NJ, USA).
Other Information
Thermal Behaviour:
Heated in a closed tube it yields a large amount of water of neutral pH. Before the blowpipe, on charcoal, it swells and emits bubbles of vapour, but does not melt; and leaves an infusible mass, of neutral pH. When moistened with a solution of cobalt nitrate and reignited the mass becomes pink.
Notes:
Dissolves readily in cold water, giving a clear solution with a bitter salty taste. Adding ammonium chloride, this solution does not give a precipitate, but when a solution of sodium phosphate is added to the ammoniacal solution, a large amount of white precipitate of ammonium-magnesium phosphate is produced. Adding HCl and barium chloride to the starting aqueous solution produces abundant white precipitate of barium sulphate.
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 Hexahydrite
mindat.org URL:
https://www.mindat.org/min-1891.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 Hexahydrite
Reference List:
Localities for Hexahydrite
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).
Struck out - Mineral was erroneously reported from this locality.
Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).
All localities listed without proper references should be considered as questionable.
All localities listed without proper references should be considered as questionable.
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| Kampf, A. R., Mills, S. J., Nash, B. P., Housley, R. M., Rossman, G. R., Dini, M. (2013) Camaronesite, [Fe3+(H2O)2(PO3OH)]2(SO4)·1–2H2O, a new phosphate-sulfate from the Camarones Valley, Chile, structurally related to taranakite. Mineralogical Magazine, 77 (4) 453-465 doi:10.1180/minmag.2013.077.4.05 |
Kampf, A. R., Mills, S. J., Nash, B. P., Housley, R. M., Rossman, G. R., Dini, M. (2013) Camaronesite, [Fe3+(H2O)2(PO3OH)]2(SO4)·1–2H2O, a new phosphate-sulfate from the Camarones Valley, Chile, structurally related to taranakite. Mineralogical Magazine, 77 (4) 453-465 doi:10.1180/minmag.2013.077.4.05 | |
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| Joan Abella i Creus (Joanabellacreus@gmail.com) specimens and analyses by EDS and XRD.Identification: XRD, SEM-EDS |
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Lengenbach Quarry, Fäld, Binn, Goms, Valais, Switzerland