Anhydrite Mineral Data

Anhydrite Mineral Data +

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General Anhydrite Information

Chemical Formula:

CaSO4

Composition:

Molecular Weight = 136.14 gm

Calcium 29.44 % Ca 41.19 % CaO

Sulfur 23.55 % S 58.81 % SO₃

Oxygen 47.01 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca(SO₄)

Environment:

Sedimentary beds, gangue in ore veins, and in traprock zeolite occurrences.

IMA Status:

Valid Species (Pre-IMA) 1795

Locality:

World wide occurrences where marine evaporite beds occur. Often interbedded with halite. Link to MinDat.org Location Data.

Name Origin:

From the Greek anhydros, meaning "waterless" (In contrast to Gypsum, which contains water).

Synonym:

Calcium Sulfate

ICSD 16382

PDF 37-1496

Anhydrite Image

Images:

Anhydrite

Comments: Several terminated groups of light blue anhydrite crystals in parallel growth.
Location: Naica. Chihuahua, Mexico. Scale: 9.5 x 8 x 6 cm.
© Isaias Casanova / IC Minerals

Anhydrite Crystallography

Axial Ratios:

a:b:c =0.9992:1:0.8916

Cell Dimensions:

a = 6.991, b = 6.996, c = 6.238, Z = 4; V = 305.09 Den(Calc)= 2.96

Crystal System:

Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: Amma

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

By Intensity(I/I_o): 3.49(1), 2.849(0.35), 2.328(0.2),

Forms:

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Crystal Structure:

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Hawthorne F C , Ferguson R B , The Canadian Mineralogist , 13 (1975) p.289-292, Anhydrous sulphates. II. Refinement of the crystal structure of anhydrite

Physical Properties of Anhydrite

Cleavage:

[010] Perfect, [100] Perfect, [001] Good

Color:

Colorless, White, Bluish white, Violet white, Dark gray.

Density:

2.96 - 2.98, Average = 2.97

Diaphaniety:

Transparent to Subtransparent to translucent

Fracture:

Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.

Habit:

Massive - Fibrous - Distinctly fibrous fine-grained forms.

Habit:

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

Habit:

Plumose - "Mica-like" minerals forming aggregates of plume-like forms.

Hardness:

3.5 - Copper Penny

Luminescence:

None.

Luster:

Vitreous - Pearly

Streak:

white

Optical Properties of Anhydrite

Gladstone-Dale:

CI meas= -0.037 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= -0.04 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1983,KPDmeas= 0.1976,KC= 0.1906

Optical Data:

Biaxial (+), a=1.569-1.573, b=1.574-1.579, g=1.609-1.618, bire=0.0400-0.0450, 2V(Calc)=44, 2V(Meas)=36-45. Dispersion r < v.

Pleochroism (x):

colorless.

Pleochroism (y):

colorless.

Pleochroism (z):

colorless.

Calculated Properties of Anhydrite

Electron Density:

r_electron=2.97 gm/cc
note: r_Anhydrite=2.97 gm/cc.

Fermion Index

Fermion Index = 0.00238
Boson Index = 0.99762

Photoelectric:

PE_Anhydrite= 5.03 barns/electron
U=PE_Anhydrite x r_electron= 14.93 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Anhydrite is Not Radioactive

Anhydrite Classification

Dana Class:

28.3.2.1 (28)Anhydrous Acid and Sulfates

(28.3)(A++) XO4

(28.3.2)Dana Group

28.3.2.1 Anhydrite CaSO4 Amma 2/m 2/m 2/m

Strunz Class:

VI/A.08-50 VI - Sulfates,Chromates,Molybdates and Tungstates

VI/A - Waterfree sulfates [SO4]2- without unfamiliar anions. cations of very big size

VI/A.08 - Aphthitalite - Anhydrite series

VI/A.08-10 Aphthitalite (K,Na)3Na(SO4)2 P 3m 3 2/m

VI/A.08-20 Kalistrontite K2Sr(SO4)2 R 3m 3 2/m

VI/A.08-30 Palmierite (K,Na)2Pb(SO4)2 R 3m 3 2/m

VI/A.08-40 Glauberite Na2Ca(SO4)2 C 2/c 2/m

VI/A.08-50 Anhydrite CaSO4 Amma 2/m 2/m 2/m

Other Anhydrite Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Heinrich65)

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Anhydrite

CaSO4
Dana No: 28.3.2.1 Strunz No: VI/A.08-50
Locality:

Notes: