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.






Sugilite Properties

Chemical Composition: 
(K,Na)(Na,Fe3+)2(Li2Fe+3)Si12O3o + Mn - Complex silicate of alkali metals, iron, aluminium etc. and has a water content.
Colors / Varieties: 
Reddish purple to purple, lavender, pink, yellow - brown / Semi-transparent to opaque.
Crystal System / Forms: 
Hexagonal / Commonly massive form, prismatic crystals.
Hardness: 
6.5 - 7.5
Specific Gravity: 
2.74
Cleavage / Fracture: 
None / Granular fracture.
Optic Character: 
Anisotropic, D.R.; Uniaxial negative. Generally aggregates (A.G.G.).
Lustre: 
Sub - vitreous
Refractive Index / Birefringence: 
1.606 - 1.610 / 0.004
Pleochroism: 
None
Dispersion: 
None
Magnification: 
Surface texture
U.V. Fluorescence: 
Inert
Spectrum: 
Bands at 411nm, 419nm, 437nm, diffused band at 570nm.
Cause of Color: 
Manganese and iron.
Specific Tests: 
Recognized by the deep violet color.
Simulants (with separation tests): 
  • Mistaken for another mineral Sogdianite (higher S.G., presence of Zr + Ti)
  • Charoite (wavy fibrous structure with sheen)
  • Dumortierite (structure)
Geological Occurrence: 
In manganese ores.
Sources: 
South Africa, Japan.
Cuts & Uses: 
Cabochons, beads, carving, etc.