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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

Nuummite

1.635

1.663

0.02

0.022

3.18

3.37

matrix: light grey to almost black; iridescence: green, metallic blue, yellow to golden, rarely violet; mostly only two colours of the same end of the spectrum

50 km of Nuuk, Greenland

cause of iridiscence : very thin lamellae of gedrite (0.8Ám) and anthophyllite (0.2Ám)

 

 

 

 

 

 

general absorption from 485, broad lines at 505 and 545nm

dark violet

dark violet

Gems & Gemology 1987 spring, p36-42

Nuummite

1.649

1.669

 

 

2.93

3.03

black, dark brown, with blue and bluish green or golden iridescence

Sahara Desert, Mauretania

cabochons of 8-20ct

 

 

 

 

 

 

 

inert

inert

Gems & Gemology 2011 Fall, p242-243

Nuummite

1.65

1.65

 

 

3.2

3.2

 

 

 

 

 

 

 

 

 

 

 

 

The Australian Gemmologist 1985 November, p 461

Nuummite

1.65

1.66

 

 

3.08

3.1

violet-blue

Simiuttat, Greenland

 

 

 

 

 

 

 

no features

inert

inert

The Journal of Gemmology 2016 Vol 35 (4), p330-338

 

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

Nuummite

1.635

1.663

0.022

0.022

3.18

3.37

1.635

1.641

 

 

1.657

1.663

Gemmological Tables, Ulrich Henn, 2004 

Nuummite

1.635

1.663

0.022

0.022

3.18

3.37

1.635

1.641

 

 

1.657

1.663

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

Nuummite

1.64

1.66

0.02

0.02

3.24

3.24

 

 

 

 

 

 

Gems, R Webster, 5th edition 1994 

 

CAUSE OF COLOUR

Stone

Colour

Cause of colour

Reference

Nuummite

multicolour

iridescence, likely diffraction

Gems & Gemology Summer 1988

 

MINERAL INCLUSIONS

 

LOCALITIES

STONE

LOCALITIES

REFERENCE

nuummite

 

 

 

Greenland

Gems & Gemology 2011 Fall, p242-243

nuummite

 

Sahara Desert

 

Mauretania

Gems & Gemology 2011 Fall, p242-243

 

CHEMICAL DATA (%)