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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

Omphacite

1.667

1.67

 

 

3.34

3.44

black or blackish green

 

called inky jadeite jade, >80% omphacite

 

 

 

 

 

 

 

inert

inert

The Journal of Gemmology 2003 Vol28, N6, p337-344

Omphacite

1.67

1.68

 

 

3.33

3.41

dark greenish blue, dark blue, greyish greenish blue

Quebrada Seca, Jalapa Department, Guatemala

translucent

 

 

 

 

 

 

nihil

inert

inert

Gems & Gemology 2004 spring, p68

Omphacite

1.67

1.68

 

 

3.35

3.36

dark green

Po Valley, Piemonte, Italy

hardness 6.5, jade, translucent

 

 

 

 

 

 

 

inert

inert

The Journal of Gemmology 2006 Vol 30, No3/4 p 215-226

 

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

Omphacite

1.662

1.723

0.023

0.023

3.29

3.39

1.662

1.701

1.670

1.712

1.685

1.723

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

 

CAUSE OF COLOUR

 

MINERAL INCLUSIONS

 

LOCALITIES

 

CHEMICAL DATA (%)

Stone

Colour

Locality

Reference

SiO2

Al2O3

MnO

MgO

FeO

TiO2

CaO

Na2O

Cr2O3

Fe2O3

K2O

Omphacite

 

Po Valley

Italy

The Journal of Gemmology 2006, 3/4, p221

55.86

13.23

0.13

6.38

1.14

0.22

8.27

9.94

0.17

5.17

0.01

Omphacite

 

Po Valley

Italy

The Journal of Gemmology 2006, 3/4, p221

55.44

11.96

0.12

8.37

1.38

0.14

11.22

8.29

0.29

2.6

 

Omphacite

 

 

 

The Journal of Gemmology 2003, Vol 28,N6, p342

56.45

11.19

 

7.84

3.97

 

11.84

7.91

0.16