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INVESTIGATIONS

Stone

RI min

RI max

Dens min

Dens max

Colour

Location

Info

Spectrum

UVS

UVL

Reference

Almandine-spessartine

 

 

4.13

4.13

deep brownish red

Clearwater County, Idaho, USA

11.06ct

a strong 432.0-nm band + almandine spectrum

 

 

Gems & Gemology 1986 Fall, p 187

Almandine-spessartine

1.8

1.8

4.17

4.17

orange-red

Lindi, Tanzania

1.35ct

weak absorption lines at 480 and 520 nm, stronger lines at 460, 505, and 565 nm, and general absorption to 440 nm.

inert

inert

Gems & Gemology 2008 Summer, p165

Almandine-spessartine

1.81

1.81

4.19

4.19

 

 

2.52ct

 

 

 

Gems & Gemology 2011 Winter, p274

Almandine-spessartine

1.81

1.81

4.22

4.22

 

 

6.78ct, composition: Sps63Alm37

 

 

 

Gems & Gemology 2011 Winter, p274

Almandine-spessartine

1.812

1.812

4.26

4.26

 

 

1.62ct, composition: Sps53Alm47

 

 

 

Gems & Gemology 2011 Winter, p274

 

TABLES

Stone

RI min

RI max

Dens min

Dens max

Reference

Almandine-spessartine 

1.808

1.822

3.96

4.3

Gemmo.eu 2013

Almandine-spessartine 

1.81

1.82

4.12

4.25

http://www.gemmology.be 

Almandine-spessartine 

1.81

1.82

4.14

4.31

http://www.geminterest.com 

Almandine-spessartine 

1.81

1.82

4.12

4.25

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

 

CAUSE OF COLOUR

 

MINERAL INCLUSIONS

Inclusion

Stone

Reference

apatite

Almandine-spessartine

http://www.geminterest.com/

rutile

Almandine-spessartine

E.J. Gübelin and J.I. Koivula, Photoatlas of inclusions in Gemstones, volume 2 (2005)

 

LOCALITIES

STONE

LOCALITIES

REFERENCE

almandine-spessartine

Star garnet locality, Ambatondrazaka Department

Alaotra-Mangoro Region

Toamasina (Tamatave) Province

Madagascar

The journal of Gemmology, 2002, Vol28, N°1, p13-23

 

CHEMICAL DATA

Stone

Colour

Locality

Reference

SiO2

Al2O3

MnO

MgO

FeO

TiO2

CaO

Na2O

Cr2O3

V2O3

Fe2O3

Almandine-spessartine

reddish to purplish brown, opaque, star

Ambatondrazaka

Madagascar

The Journal of Gemmology 2002, Vol 28, N°1, p19

36.32

20.93

8.96

20

31.71

0.04

0.47

 

0.01

0.02

 

Almandine-spessartine

reddish to purplish brown, opaque, star

Ambatondrazaka

Madagascar

The Journal of Gemmology 2002, Vol 28, N°1, p19

36.28

20.87

8.6

1.9

32.5

0.06

0.36

 

0.01

0.01

 

Almandine-spessartine

reddish to purplish brown, opaque, star

Ambatondrazaka

Madagascar

The Journal of Gemmology 2002, Vol 28, N°1, p19

36.5

20.9

8.02

2.17

32.48

0.14

0.6

 

0.02

0.01

 

Almandine-spessartine

orange-red

 

Sri Lanka

The Journal of Gemmology 2007,30,5/6,307-319

35.47

20.63

16.75

0.44

24.08

0.03

0.26

0.06

0.01

 

2.14