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INVESTIGATIONS

 

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

Howlite

1.583

1.605

0.022

0.022

2.45

2.58

1.583

1.586

1.596

1.598

1.605

1.605

Joel Arem, Color Encyclopedia of Gemstones, 1987 

Howlite

1.583

1.61

0.019

0.022

2.45

2.59

1.583

1.586

1.596

1.598

1.605

1.610

http://www.geminterest.com 

Howlite

1.583

1.605

0.19

0.22

2.45

2.59

1.583

1.586

 

 

1.605

1.605

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

Howlite

1.583

1.605

0.022

0.022

2.45

2.58

 

 

 

 

 

 

http://www.gemmology.be 

Howlite

1.583

1.605

0.019

0.022

2.45

2.58

1.583

1.586

1.596

1.598

1.605

1.605

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

Howlite

1.586

1.605

0.019

0.019

2.58

2.58

 

 

 

 

 

 

Bestimmungstabellen für Edelsteine, Birgit Günther, 1981 

Howlite

1.586

1.605

0.019

0.019

2.58

2.58

1.586

1.586

1.598

1.598

1.605

1.605

Gemmological Tables, Ulrich Henn, 2004 

Howlite

1.59

1.59

 

 

2.58

2.58

 

 

 

 

 

 

John Sinkakas, Gemstone and mineral data book,1972 

Howlite

1.59

1.59

0.02

0.02

2.58

2.58

 

 

 

 

 

 

Gems, R Webster, 5th edition 1994 

 

CAUSE OF COLOUR

 

MINERAL INCLUSIONS

 

LOCALITIES

 

CHEMICAL DATA