Zoisite Mineral Data

General Zoisite Information

Chemical Formula:

Ca2Al3(SiO4)3(OH) = Ca2AlAl2(SiO4)(Si2O7)O(OH)

Composition:

Molecular Weight = 454.36 gm

Calcium 17.64 % Ca 24.68 % CaO

Aluminum 17.82 % Al 33.66 % Al₂O₃

Silicon 18.54 % Si 39.67 % SiO₂

Hydrogen 0.22 % H 1.98 % H₂O

Oxygen 45.78 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca₂Al₃Si₃O₁₂(OH)

Environment:

Metamorphic and pegmatite rocks.

IMA Status:

Valid Species (Pre-IMA) 1805

Locality:

Rauris and Saualpe, Austria. Link to MinDat.org Location Data.

Name Origin:

Named after the Austrian natural scientist, Siegmund Zois (1747-1819).

Name Pronunciation:

Zoisite

Synonym:

Anyolite - green

ICSD 66924

PDF 13-562

Tanzanite - blue

Thulite - red

Zoisite Image

Images:

Zoisite

Comments: Gem quality crystal of zoisite with the striking pleochroism displayed in three different views.
Location: Alchuri Village, Shigar Valley, north of Skardu, Baltistan, Pakistan. Scale: 1x1x3.8 cm.
© Dan Weinrich

Images:

Zoisite

Comments: Dual views of a large crystal of blue-violet zoisite (var. tanzanite) showing the pleochroism.
Location: Merelani Hills, Umba Valley, Lelatema Mts., Arusha Region, Tanzania. Scale: 35 mm 42.32 ct.
© John Betts - Fine Minerals

Zoisite Crystallography

Axial Ratios:

a:b:c =2.9103:1:1.81

Cell Dimensions:

a = 16.24, b = 5.58, c = 10.1, Z = 4; V = 915.25 Den(Calc)= 3.30

Crystal System:

Orthorhombic - Dipyramidal H-M Symbol (2/m 2/m 2/m) Space Group: Pnmc

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

By Intensity(I/I_o): 2.69(1), 2.87(0.65), 4.03(0.5),

Forms:

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Forms: ( 1 0 0) ( 1 1 1) ( 0 0 1)

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Physical Properties of Zoisite

Cleavage:

{001} Perfect

Color:

Gray, Apple green, Brown, Blue, Rose red.

Density:

3.3

Diaphaneity:

Transparent to subtranslucent

Fracture:

Even - Flat surfaces (not cleavage) fractured in an even pattern.

Habit:

Columnar - Forms columns

Habit:

Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).

Habit:

Striated - Parallel lines on crystal surface or cleavage face.

Hardness:

6.5 - Pyrite

Luminescence:

Non-fluorescent.

Luster:

Vitreous - Pearly

Streak:

white

Optical Properties of Zoisite

Gladstone-Dale:

CI meas= -0.01 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.01 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2128,KPDmeas= 0.2128,KC= 0.2108
Ncalc = 1.7

Optical Data:

Biaxial (+), a=1.696-1.7, b=1.696-1.702, g=1.702-1.718, bire=0.0060-0.0180, 2V(Calc)=0-40, 2V(Meas)=0-70. Dispersion relatively strong.

Pleochroism (x):

colorless or pale pink.

Pleochroism (y):

colorless or colorless.

Calculated Properties of Zoisite

Electron Density:

Bulk Density (Electron Density)=3.28 gm/cc
note: Specific Gravity of Zoisite =3.30 gm/cc.

Fermion Index:

Fermion Index = 0.0091183238
Boson Index = 0.9908816762

Photoelectric:

PE_Zoisite= 3.40 barns/electron
U=PE_Zoisite x rElectron Density= 11.17 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Zoisite is Not Radioactive

Zoisite Classification

Dana Class:

58.02.01b.01 (58)Sorosilicate Insular, Mixed, Single, and Larger Tetrahedral Groups

(58.02)with cations in [6] and higher coordination; single and double groups (n=1,2)

(58.02.01b)Epidote group (Zoisite subgroup)

58.02.01b.01 Zoisite Ca2Al3(SiO4)3(OH)=Ca2AlAl2(SiO4)(Si2O7)O(OH) Pnmc 2/m 2/m 2/m

Strunz Class:

09.BG.10 09 - SILICATES (Germanates)

09.B - Sorosilicates

09.BG -Sorosilicates with mixed SiO4 and Si2O7 groups;

09.BG.10 Zoisite Ca2Al3(SiO4)3(OH)=Ca2AlAl2(SiO4)(Si2O7)O(OH) Pnmc 2/m 2/m 2/m

Other Zoisite Information

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Zoisite

Ca2Al3(SiO4)3(OH) = Ca2AlAl2(SiO4)(Si2O7)O(OH)
Dana No: 58.02.01b.01 Strunz No: 09.BG.10
Locality:

Notes:

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