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 % H₂O

Sulfur 15.24 % S 38.05 % SO₃

Oxygen 68.42 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Mg(SO₄)•5(H₂O)

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

Comments: White, powdery pentahydrite.
Location: Shaft 371, Schlema-Hartenstein area, Erzgebirge, Saxony, Germany. Scale: Picture size 4 mm.
© Thomas Witzke / Abraxas-Verlag

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 - PinacoidalH-M Symbol ( 1) Space Group: P1

Crystal Structure:

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Help on Above

Peterson R C , Hammarstrom J M , Seal R R , American Mineralogist , 91 (2006) p.261-269, Alpersite (Mg,Cu)SO4*7H2O, a new mineral of the melanterite group, and cuprian, pentahydrite: Their occurrence within mine waste, Locality: Big Mike mine, Nevada, USA

View Additional jPOWD Structure files for Pentahydrite
[1] [2]

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:

PE_Pentahydrite= 1.29 barns/electron
U=PE_Pentahydrite x rElectron 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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Ask about Pentahydrite here :
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Print or Cut-and-Paste your Pentahydrite Specimen Label here :

Pentahydrite

MgSO4•5(H2O)
Dana No: 29.06.07.03 Strunz No: 07.CB.20
Locality:

Notes: