Pentahydrite Mineral Data
General Pentahydrite Information
Chemical Formula:
MgSO4•5(H2O)
Composition:
Molecular Weight = 210.45 gm
Magnesium 11.55 % Mg 19.15 % MgO
Hydrogen 4.79 % H 42.80 % H2 O
Sulfur 15.24 % S 38.05 % SO3
Oxygen 68.42 % O
______ ______
100.00 % 100.00 % = TOTAL OXIDE
Empirical Formula:
Mg(SO4 )•5(H2 O)
Environment:
Pseudomorphs of dehydration of epsomite.
IMA Status:
Valid Species (Pre-IMA) 1951
Locality:
The Geysers, Sonoma County, California, USA. Link to MinDat.org Location Data.
Name Origin:
Named from the Greek, penta, "five" and hydros "water" in allusion to the 5 water molecules in the formula.
Name Pronunciation:
Pentahydrite + Pronunciation
Synonym:
ICSD 2776
PDF 25-532
Pentahydrite Image
Images:
Pentahydrite Crystallography
Axial Ratios:
a:b:c =0.6004:1:0.5758
Cell Dimensions:
a = 6.335, b = 10.55, c = 6.075, Z = 2; alpha = 99.17°, beta = 109.88°, gamma = 75° V = 364.10 Den(Calc)= 1.92
Crystal System:
Triclinic - Pinacoidal H-M Symbol ( 1 ) Space Group: P1
Physical Properties of Pentahydrite
Cleavage:
None
Color:
White, Light blue, Light greenish blue.
Density:
1.9
Diaphaneity:
Transparent to Translucent
Habit:
Efflorescences - Crystals covering matrix, generally produced from transpiro-evaporation.
Habit:
Granular - Generally occurs as anhedral to subhedral crystals in matrix.
Hardness:
2.5 - Finger Nail
Luster:
Vitreous (Glassy)
Streak:
white
Optical Properties of Pentahydrite
Gladstone-Dale:
CI meas = -0.025 (Excellent) - where the CI = (1-KPDmeas /KC ) CI calc = -0.025 (Excellent) - where the CI = (1-KPDcalc /KC )
KPDcalc = 0.2574,KPDmeas = 0.2574,KC = 0.2512 Ncalc = 1.48
Optical Data:
Biaxial (-), a=1.482, b=1.492, g=1.493, bire=0.0110, 2V(Calc)=34, 2V(Meas)=45.13.
Calculated Properties of Pentahydrite
Electron Density:
Bulk Density (Electron Density)=1.99 gm/cc note: Specific Gravity of Pentahydrite =1.90 gm/cc.
Fermion Index:
Fermion Index = 0.01 Boson Index = 0.99
Photoelectric:
PEPentahydrite = 1.29 barns/electronU=PEPentahydrite x r Electron Density= 2.56 barns/cc.
Radioactivity:
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Pentahydrite is Not Radioactive
Pentahydrite Classification
Dana Class:
29.06.07.03 (29) Hydrated Acid and Sulfates
(29.06) where A XO4 � x(H2O)
(29.06.07) Chalchanthite Group (Triclinic: P-1)
29.06.07.01 Chalcanthite CuSO4•5(H2O) P1 1
29.06.07.02 Siderotil FeSO4•5(H2O) P1 1
29.06.07.03 Pentahydrite MgSO4•5(H2O) P1 1
29.06.07.04 Jokokuite MnSO4•5(H2O) P1 1
Strunz Class:
07.CB.20 07 - SULFATES (SELENATES, TELLURATES)
07.C - Sulfates (selenates, etc.) without Additional Anions, with H2O
07.CB -With only medium-sized cations
07.CB.20 Chalcanthite CuSO4•5(H2O) P1 1
07.CB.20 Jokokuite MnSO4•5(H2O) P1 1
07.CB.20 Pentahydrite MgSO4•5(H2O) P1 1
07.CB.20 Siderotil FeSO4•5(H2O) P1 1
Other Pentahydrite Information
References:
NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)
See Also:
Links to other databases for Pentahydrite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - MinDAT
10 - Mineralienatlas (Deutsch)
11 - Online Mineral Museum
12 - QUT Mineral Atlas
13 - Ruff.Info
14 - WWW-MINCRYST
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Pentahydrite
MgSO4•5(H2O)
Dana No: 29.06.07.03 Strunz No: 07.CB.20
Locality:
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