Ekanite

Ekanite is green to brown colored rare stone with chemical composition calcium thorium silicate. Thorium is a highly radio active element and due to this element Ekanite is converted to metamict state. In metamict state Ekanite almost acts like amorphous. By applying heat at certain temperature the metamict state of Ekanite can be restored to crystalline state. The main source for Ekanite is Sri Lanka and Canada.

Properties

Chemical Composition: 

Calcium Thorium Silicate - ThCa₂Si₈O₂₀

Classification / Type: 

It is a metamict mineral.

Colors / Varieties: 

• Green, brown (metamict)
• Yellow, red (crystalline)
• Four rayed star

Crystal System / Forms: 

Tetragonal System / Prismatic crystals and water-worn pebbles.

Hardness: 

6 - 6.5

Specific Gravity: 

3.28

Cleavage / Fracture: 

None / Conchoidal.

Optic Character: 

Anisotropic, D.R.; Uniaxial negative. Is almost amorphous and appears Isotropic (S.R.) due to metamict state.

Lustre: 

Vitreous.

Refractive Index / Birefringence: 

• Metamict: 1.597
• Crystalline: 1.568 - 1.580 / 0.012

Pleochroism: 

Not common.

Dispersion: 

-

Magnification: 

Crystalline inclusions.

U.V. Fluorescence: 

Variable.

Spectrum: 

Not characteristic.

Cause of Color: 

-

Treatment (Enhancement): 

Heat treatment restores crystalline state.

Specific Tests & Remarks: 

Highly radioactive.

Synthesis: 

-

Simulants (with key separation tests): 

Moldavite (R.I., S.G., inclusions), Brazilianite (optic figure, R.I., birefringence).

Geological Occurrence: 

Alluvial deposits.

Sources: 

Sri Lanka, Canada.

Cuts & Uses: 

Facetted, cabochon, etc.