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Sugilite

sugilite
Tumbled sugilite

Sugilite is deep reddish purple to purple, semi-transparent to opaque, complex silicate of alkali metals, iron, aluminium, etc. with water content. It is normally occurred in massive form with small crystals.

Sugilite can be confused with a similar appearing mineral called Sogdianite, which can be distinguished by specific gravity and presence of zirconium and titanium in Sogdianite. Sugilite is mainly sourced from Japan and South Africa. It is widely used as beads in jewelry making.

Cause of Color : Manganese and iron.
Chemical Composition :

(K,Na)(Na,Fe3+)2(Li2Fe+3)Si12O3o + Mn – Complex silicate of alkali metals, iron, aluminium etc. and has a water content.


Crystal System / Forms :

Hexagonal / Commonly massive form, prismatic crystals.


Cuts & Uses :

Cabochons, beads, carving, etc.


Dispersion : None
Hardness : 6.5 - 7.5
Lustre : Sub - vitreous
Magnification :

Surface texture


Optic Character :

Anisotropic, D.R.; Uniaxial negative. Generally aggregates (A.G.G.).


Pleochroism : None
Refractive Index / Birefringence :

1.606 – 1.610 / 0.004


Simulants (with separation tests) :
  • Mistaken for another mineral Sogdianite (higher S.G., presence of Zr + Ti)
  • Charoite (wavy fibrous structure with sheen)
  • Dumortierite (structure)

Sources :

South Africa, Japan.


Specific Tests :

Recognized by the deep violet color.


Spectrum :

Bands at 411nm, 419nm, 437nm, diffused band at 570nm.


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