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INVESTIGATIONS

Stone

RI min

RI max

Biref min

Biref max

Dens min

Dens max

Colour

Locality

Info

nx min

nx max

ny min

ny max

nz min

nz max

Spectrum

UVS

UVL

Reference

Cordierite

1.52

1.541

 

 

2.57

2.57

colourless

Embilipitiya, Sri Lanka

 

 

 

 

 

 

 

 

 

 

Gems & Gemology 1996 winter, p262-269

Cordierite

1.52

1.541

0.01

0.01

2.57

2.57

nearly colourless

Embilipitiya, Sri Lanka

very Mg-rich

 

 

 

 

 

 

 

 

 

The Australian Gemmologist 1986 Vol 16, Nr 2, p35-40

Cordierite

1.527

1.536

0.009

0.009

2.55

2.55

colourless

Sri Lanka

 

1.527

1.527

1.532

1.532

1.536

1.536

 

 

 

Zeitschrift der Deutschen Gemmologischen Gesellschaft 1985 34, Nr1/2, p79-80

Cordierite

1.528

1.54

 

 

2.548

2.554

red

Iakora district, Fianarantsoa province, in southeast Madagascar

1.28ct, 2.69ct and 4.17ct, Usambara effect, very strong pleochroism: deep red to orange to greyish brown with a hint of blue or purple

1.528

1.530

1.532

1.533

1.538

1.540

 

 

 

Gems & Gemology 2016 Spring, p 97

Cordierite

1.529

1.538

0.009

0.009

2.55

2.55

brownish orange

Iakora, Madagascar

2.96ct

 

 

 

 

 

 

 

inert

very faint red

http://www.spec4gem.info/index.php 2016

Cordierite

1.53

1.543

0.013

0.013

2.65

2.65

colourless

 

3ct

 

 

 

 

 

 

 

 

 

ACAM lab

Cordierite

1.53

1.54

0.01

0.01

2.53

2.55

orange-red to yellowish brown

Madagascar

2.55, 3.17 and 3.63ct

1.530

1.530

1.533

1.534

1.540

1.540

strong band near 500nm

inert

inert

The Journal of Gemmology 2016 Vol 35, No. 1, p 8-9

Cordierite

1.531

1.54

0.009

0.009

2.65

2.65

colourless

 

0.26ct

 

 

 

 

 

 

 

 

 

ACAM lab  886

Cordierite

1.531

1.541

0.01

0.01

2.62

2.62

colourless

 

1.48ct, lamellar twinning

1.531

1.531

1.534

1.534

1.541

1.541

 

inert

inert

Gems & Gemology 1998 winter, p 295-296

Cordierite

1.531

1.542

0.009

0.009

2.59

2.6

greyish violet to violet

Palmer Canyon, Laramie Mts, Wyoming

0.36-1.33 ct

1.531

1.533

 

 

1.540

1.542

no features

 

 

Gems & Gemology 2001 Winter, p336-337

Cordierite

1.532

1.541

0.009

0.009

2.57

2.57

brown

Madagascar

 

 

 

 

 

 

 

band 490

inert

inert

Gems & Gemology 2004 winter, p328

Cordierite

1.532

1.549

0.017

0.017

2.562

2.562

colourless

 

0.26ct

 

 

 

 

 

 

 

 

 

ACAM lab

Cordierite

1.532

1.548

0.016

0.016

2.59

2.59

colourless

 

0.25ct

 

 

 

 

 

 

 

 

 

ACAM lab 

Cordierite

1.532

1.55

0.018

0.018

2.59

2.59

violet

 

 

 

 

 

 

 

 

 

 

 

ACAM lab 

Cordierite

1.532

1.546

0.01

0.012

2.55

2.57

blue

Kragerö, Norway

 

1.532

1.534

1.537

1.540

1.542

1.546

 

 

 

Zeitschrift der Deutschen Gemmologischen Gesellschaft 1990 Sep, p99-106

Cordierite

1.535

1.54

0.005

0.005

2.69

2.69

violet

Beraketa, Toliara Province, Madagascar

2.69ct

 

 

 

 

 

 

broad absorption below 420nm

inert

inert

GIA Gem Database  34405

Cordierite

1.536

1.548

0.012

0.012

2.59

2.59

 

Madagascar

1.33ct

 

 

 

 

 

 

 

inert

inert

Gems & Gemology 1995 Spring, p62

Cordierite

1.537

1.55

0.013

0.013

2.58

2.58

colourless

Sri Lanka

3.81ct

 

 

 

 

 

 

 

 

 

Gemmologie, Zeitschrift der Deutschen Gemmologischen Gesellschaft 1999 Jul p106

Cordierite

1.538

1.549

0.011

0.011

2.575

2.575

violet

 

2.36ct

 

 

 

 

 

 

 

 

 

ACAM lab 

Cordierite

1.539

1.55

0.011

0.011

2.605

2.605

violet

 

0.8ct

 

 

 

 

 

 

 

 

 

ACAM lab 

Cordierite

1.539

1.546

0.007

0.007

2.58

2.58

violetish blue

Mogok, Myanmar

10.14ct

 

 

 

 

 

 

line at 467nm

inert

inert

GIA Gem Database  34555

Cordierite

1.54

1.549

0.009

0.009

2.59

2.59

blue

 

2.59ct

 

 

 

 

 

 

 

inert

inert

ACAM lab  3850

Cordierite

1.54

1.54

 

 

2.56

2.56

greyish blue

 

cabochon, cat's-eye, translucent, 13.91ct, spot RI

 

 

 

 

 

 

faint lines at 490 nm and 590nm

 

 

Gems & Gemology 1982 Fall, p171

Cordierite

1.547

1.515

0.037

0.037

2.56

2.56

dark orangy red

 

 

 

 

 

 

 

 

 

 

 

Gems & Gemology 2017 Spring, p91-92

 

TABLES

Stone

RI min

RI max

Biref min

Biref max

Dens min

Dens max

nx min

 nx max

ny min

ny max

nz min

nz max

Reference

Cordierite

1.522

1.578

0.008

0.012

2.53

2.78

1.522

1.558

 

 

1.524

1.578

Gemme, Dati per l'identificazione, P. De Stefano et al, 1993 

Cordierite

1.522

1.578

0.005

0.018

2.53

2.78

 

 

 

 

 

 

http://www.gemmology.be 

Cordierite

1.522

1.578

0.005

0.018

2.53

2.78

1.522

1.558

1.524

1.574

1.527

1.578

http://www.geminterest.com 

Cordierite

1.522

1.578

0.005

0.018

2.53

2.78

1.522

1.558

1.524

1.574

1.527

1.578

Joel Arem, Color Encyclopedia of Gemstones, 1987 

Cordierite

1.522

1.578

0.005

0.02

2.53

2.78

1.522

1.558

1.524

1.574

1.527

1.578

Tables of Gemstone Identification, Roger Dedeyn, Ivo Quintens, 2007 

Cordierite

1.522

1.596

0.005

0.018

2.56

2.66

 

 

 

 

 

 

Gemology Tools Professional 2010

Cordierite

1.526

1.579

0.006

0.018

2.52

2.67

 

 

 

 

 

 

Gemmo.eu 

Cordierite

1.527

1.596

0.008

0.01

2.55

2.66

 

 

 

 

 

 

Bestimmungstabellen für Edelsteine, Birgit Günther, 2008 

Cordierite

1.527

1.578

0.008

0.018

2.53

2.78

1.527

1.560

1.532

1.574

1.536

1.578

Gemmological Tables, Ulrich Henn, 2004 

Cordierite

1.53

1.55

0.008

0.012

2.57

2.66

1.530

1.540

 

 

1.540

1.550

Gems, R Webster, 5th edition 1994 

Cordierite

1.53

1.539

0.009

0.009

2.58

2.58

 

 

 

 

 

 

Tables of Gemstone Identification, Roger Dedeyn, Ivo Quintens, 2007 

Cordierite

1.532

1.556

0.008

0.012

2.57

2.66

1.532

1.550

 

 

1.540

1.556

Tabellen zur Edelstein-Bestimmung, Pschichholz FGA, 1975 

Cordierite

1.537

1.55

0.008

0.012

2.58

2.64

 

 

 

 

 

 

John Sinkakas, Gemstone and mineral data book,1972 

 

CAUSE OF COLOUR

Stone

Colour

Cause of colour

Reference

Cordierite

violet, blue

Fe²+-O-Fe³+ charge transfer, yellow // c-axis : Fe³+

Gems & Gemology Summer 1988

Cordierite

red (bloodshot iolite)

hematite and or lepidocrocoite inclusions

Gems & Gemology Summer 1988

 

MINERAL INCLUSIONS

Inclusion

Stone

Reference

apatite

Cordierite

Gemmological Tables, Ulrich Henn , GGA, 2004

hematite

Cordierite

Gemmological Tables, Ulrich Henn , GGA, 2004

lepidocrocite

Cordierite

Internal World of Gemstones, Gübelin, 1983

magnetite

Cordierite

Internal World of Gemstones, Gübelin, 1983

mica

Cordierite

Gemmological Tables, Ulrich Henn , GGA, 2004

phlogopite

Cordierite

The Journal of Gemmology, 2016, Vol 35, No. 1, p 8-9

quartz

Cordierite

The Journal of Gemmology, 2016, Vol 35, No. 1, p 8-9

rutile

Cordierite

Gemmological Tables, Ulrich Henn , GGA, 2004

tourmaline

Cordierite

The Journal of Gemmology, 2016, Vol 35, No. 1, p 8-9

zircon

Cordierite

Joel Arem, Color Encyclopedia of Gemstones, 1987

 

LOCALITIES

STONE

LOCALITIES

REFERENCE

Cordierite

 

Nova Palmeira

Paraiba

Brazil

Gems & Gemology 2000 winter p324

Cordierite

Santa Barbara mine

Parelhas

Rio Grande do Norte

Brazil

Gems  & Gemology Spring 2005, p58

Cordierite

 

Passmore

British Columbia

Canada

InColor Fall-Winter 2007-2008 p24

Cordierite

Slocan Valley

Selkirk Mts

British Columbia

Canada

Gems & Gemology 2000 winter p324

Cordierite

Ghost Lake, Yellowknife

Mackenzie District

Northwest Territories

Canada

Natural History Museum Vienna collection

Cordierite

 

Tumkur

Karanataka

India

Gems & Gemology 2000 winter p324

Cordierite

Manmunda

Boudh

Orissa

India

Gems & Gemology 2000 winter p324

Cordierite

Kantamal

Boudh

Orissa

India

Gems & Gemology 2000 winter p324

Cordierite

Urharanga

Kalahandi

Orissa

India

Gems & Gemology 2000 winter p324

Cordierite

Orhabahal

Kalahandi

Orissa

India

Gems & Gemology 2000 winter p324

Cordierite

Burhapara

Nawapada

Orissa

India

Gems & Gemology 2000 winter p324

Cordierite

Bommagoundamur

Karur

Tamil Nadu

India

Gems & Gemology 2000 winter p324

Cordierite

Uthampatty

Karur

Tamil Nadu

India

Gems & Gemology 2000 winter p324

Cordierite

Madurai District

Madurai District

Tamil Nadu

India

Gems & Gemology 2000 winter p324

Cordierite

Ibity Mt

Sahatany Valley

Antananarivo

Madagascar

Gems & Gemology 2000 winter p324

Cordierite

 

 

Tuléar (Toliara) Province

Madagascar

Gemmologie, Dez 1999,p196

Cordierite

 

Kragero

Telemark

Norway

Zeitschrift der Deutschen Gemmologischen Gesellschaft 1990, Sep, p99

Cordierite

Avissawella

Kegalla

Central Proviince

Sri Lanka

Gems & Gemology 2000 winter p324

Cordierite

 

Kurunegala

Central Proviince

Sri Lanka

Gems & Gemology 2000 winter p324

Cordierite

Hatton

Nuwara Elyia

Central Province

Sri Lanka

Gems & Gemology 2000 winter p324

Cordierite

Elahera

Polonnaruwa

Central Province

Sri Lanka

Gems & Gemology 2000 winter p324

Cordierite

Ratnapura

Ratnapura

Sabaragamuwa province

Sri Lanka

Gems & Gemology 2000 winter p324

Cordierite

Embilipitiya

Monaragata

Southern Province

Sri Lanka

Gems & Gemology 2000 winter p324

Cordieriet

Palmer Canyon vermiculite deposit

Albany County

Wyoming

USA

Gems & Gemology 2001 Winter,p336

 

CHEMICAL DATA

Stone

Colour

Locality

Reference

SiO2

Al2O3

MgO

FeO

TiO2

CaO

Na2O

Fe2O3

K2O

Cordierite

almost colourless

Embilipitiya

Sri Lanka

The Australian Gemmologist Feb 1986, Vol 16, Nr1, p3

49.51

32.98

12.64

0.95

0.02

0.01

0.08

0.14

0.01

Cordierite

almost colourless

Embilipitiya

Sri Lanka

The Australian Gemmologist Feb 1986, Vol 16, Nr1, p3

49.38

33.05

12.77

0.28

 

 

0.12

0.85

0.02

Cordierite

almost colourless

Embilipitiya

Sri Lanka

The Australian Gemmologist Feb 1986, Vol 16, Nr1, p3

49.31

33.08

11.47

0.98

 

 

0.1

 

0.01

Cordierite

blue

Kragerö

Norway

Zeitschrift der Deutschen Gemmologischen Gesellschaft, 1990, Sep, p101

48.88

33.78

13.13

1.41

 

 

0.38

 

 

Cordierite

blue

Kragerö

Norway

Zeitschrift der Deutschen Gemmologischen Gesellschaft, 1990, Sep, p101

47.52

32.9

12.8

1.43

 

 

0.37

 

 

Cordierite

blue

Kragerö

Norway

Zeitschrift der Deutschen Gemmologischen Gesellschaft, 1990, Sep, p101

46.48

32.38

12.56

1.46

 

 

0.37

 

 

Cordierite

blue

Kragerö

Norway

Zeitschrift der Deutschen Gemmologischen Gesellschaft, 1990, Sep, p101

47.14

32.9

12.81

1.68

 

 

0.4