Spessartite Garnet

Gem-quality spessartite (also known as spessartine) is uncommon. It is bright orange when pure, but an increase in the iron content makes the stone darker orange to red. Inclusions are lace - or feather-like.Spessartite occurs in granitic pegmatites and alluvial deposits. It is found in Sri Lanka, Madagascar, Brazil, Sweden, Australia, Burma, and the USA; also Germany and Italy, but crystals there are too small to facet.
Spessartine is named after Spessart district of Bavaria, Germany. It can be confused with hessonite garnet or yellow topaz, but on close examination of inclusions it is distinguishable.

Properties

Chemical Composition: 

Manganese Aluminium Silicate - Mn₃Al₂(SiO₄)₃

Colors / Varieties: 

• Orange, orange-red, brownish red.
• Chatoyant variety found.

Hardness: 

7.25

Specific Gravity: 

4.12 - 4.20

Refractive Index / Birefringence: 

1.790 - 1.830

Dispersion: 

0.027

Magnification: 

Wavy feathers formed by minute drops of liquid having a shredded appearance, fine needles / fibers and crystals.

U.V. Fluorescence: 

Inert

Spectrum: 

Bands at 412nm, 424nm, 432nm. Also bands at 462nm, 485nm, 495nm due to the presence of iron.

Cause of Color: 

Manganese, Iron

Treatment (Enhancement): 

-

Specific Tests & Remarks: 

-

Simulants (with key separation tests): 

Malaya Garnet / Pyralspite with Grossular (spectrum, inclusions), Synthetic Cubic Zirconia (lustre, spectrum, S.G.), Hessonite (R.I., S.G., spectrum, inclusions), Glass (inclusions, spectrum, U.V. fluorescence), Fire Opal (lustre, R.I., S.G.), etc.

Sources: 

Namibia, Pakistan, India, Madagascar, Brazil, Sri Lanka, Nigeria.

Cuts & Uses: 

Facetted, cabochon, beads, carvings, etc.