Picromerite Mineral Data

Picromerite Mineral Data +

General Picromerite Information

Chemical Formula:

K2Mg(SO4)2·6(H2O)

Composition:

Molecular Weight = 402.72 gm

Potassium 19.42 % K 23.39 % K₂O

Magnesium 6.04 % Mg 10.01 % MgO

Hydrogen 3.00 % H 26.84 % H₂O

Sulfur 15.92 % S 39.76 % SO₃

Oxygen 55.62 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

K₂Mg(SO₄)₂·6(H₂O)

Environment:

Volcanic fumaroles and marine evaporite deposits.

IMA Status:

Valid Species (Pre-IMA) 1855

Locality:

Vesuvius, Italy Link to MinDat.org Location Data.

Name Origin:

From the Greek for "bitter" and "part" in allusion to the magnesium content which makes this water-soluble salt bitter to the taste.

Synonym:

ICSD 26772

PDF 21-1400

Schoenite

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Picromerite Crystallography

Axial Ratios:

a:b:c =0.7395:1:0.4987

Cell Dimensions:

a = 9.064, b = 12.256, c = 6.113, Z = 2; beta = 104.8° V = 656.55 Den(Calc)= 2.04

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: P 2₁/a

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 3.706(1), 4.064(0.95), 4.156(0.85),

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Crystal Structure:

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Kannan K K , Viswamitra M A , Zeitschrift fur Kristallographie , 122 (1965) p.161-174, Crystal structure of magnesium potassium sulfate hexahydrate MgK2(SO4)2*6(H2O), Locality: synthetic

Physical Properties of Picromerite

Cleavage:

[201] Perfect

Color:

Colorless, Gray, Yellow, White, Reddish.

Density:

2.028

Diaphaniety:

Transparent

Habit:

Massive - Granular - Common texture observed in granite and other igneous rock.

Hardness:

2.5 - Finger Nail

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Picromerite

Gladstone-Dale:

CI meas= -0.011 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.005 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2286,KPDmeas= 0.23,KC= 0.2275

Optical Data:

Biaxial (+), a=1.4607, b=1.4629, g=1.4755, bire=0.0148, 2V(Calc)=46, 2V(Meas)=47.9.

Calculated Properties of Picromerite

Electron Density:

r_electron=2.09 gm/cc
note: r_Picromerite=2.04 gm/cc.

Fermion Index

Fermion Index = 0.00752
Boson Index = 0.99248

Photoelectric:

PE_Picromerite= 3.04 barns/electron
U=PE_Picromerite x r_electron= 6.35 barns/cc.

Radioactivity:

GRapi = 286.60 (Gamma Ray American Petroleum Institute Units)

Estimated Radioactivity from Picromerite - barely detectable

Picromerite Classification

Dana Class:

29.3.6.1 (29)Hydrated Acid and Sulfates

(29.3)where (A+)2 B (XO4)2 · x(H2O)

(29.3.6)Dana Group

29.3.6.1 Picromerite K2Mg(SO4)2·6(H2O) P 2₁/a 2/m

29.3.6.2 Cyanochroite K2Cu(SO4)2·6(H2O) P 2₁/a 2/m

Strunz Class:

VI/C.19-10 VI - Sulfates,Chromates,Molybdates and Tungstates

VI/C - Water-bearing sulfates without unfamiliar anions. cations of medium and very big size

VI/C.19 - Picromerite group

VI/C.19-10 Picromerite K2Mg(SO4)2·6(H2O) P 2₁/a 2/m

VI/C.19-20 Cyanochroite K2Cu(SO4)2·6(H2O) P 2₁/a 2/m

VI/C.19-30 Boussingaultite (NH4)2Mg(SO4)2·6(H2O) P 2₁/a 2/m

VI/C.19-40 Nickel-boussingaultite (NH4)2(Ni,Mg)(SO4)2·6(H2O) P 2₁/a 2/m

VI/C.19-50 Mohrite (NH4)2Fe(SO4)2·6(H2O) P 2₁/c 2/m

Other Picromerite Information

References:

NAME( Dana7) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

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Picromerite

K2Mg(SO4)2·6(H2O)
Dana No: 29.3.6.1 Strunz No: VI/C.19-10
Locality:

Notes: