Spodumene

Spodumene occurs in a range of colours, although the most common is yellowish grey. Two gem varieties: lilac pink kunzite (coloured by manganese) and bright emerald green hiddenite (coloured by chromium) – are very popular by collectors, although perfect cleavage makes them fragile gemstones. Strong pleochroism is easily seen in gem material, showing colorless and two shades of the body color when viewed from different directions. Stones should always be cut to show the best color through the table facet. The pink color may fade with time, but some material is irradiated to intensify it.

Spodumene was discovered in 1877 in Brazil, although it was not until 1879 that kunzite and hiddenite were recognized as different varieties of the same mineral. Spodumene is also found in Madagascar, Burma, United States, Canada, the former USSR, Mexico and Sweden.

Lilac pink kunzite is named after the gemmologist G.F. Kunz, who first described it in 1902; hiddenite is named after W.E. Hidden, who discovered it in North Carolina in 1879.

Cause of Color :

Yellowish green: Ferric iron

Chemical Composition :

Silicate of Lithium and Aluminium where sodium, iron or calcium may replace lithium. LiAl(SiO3)O2

Crystal System / Forms :

Monoclinic System / Long, flat, deeply striated crystals with steep terminations, often have a wood-like surface alteration; massive.

Cuts & Uses :

Facetted cuts, cabochon, beads, carvings, etc. (table facet should be cut at right angles to the c-axis for best color).

Dispersion : 0.017
Hardness : 7
Lustre : Vitreous
Magnification :

Primary fluid inclusions, complex three phase liquid inclusions, needle-like etch tubes, twin planes and cleavage cracks, crystalline inclusions.

Optic Character :

Anisotropic, D.R.; Biaxial positive

Refractive Index / Birefringence :

1.660 – 1.675 / 0.015; Range: 1.655 – 1.671

Sources :

Brazil, Sri Lanka, U.S.A.

Specific Tests :

In different lighting, exhibits reversible darkening and lightening of color.

Spectrum :

Yellow / yellowish green: Band at 437nm with a weaker band at 433nm.

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