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Xaxim is a type of petrified tree fern from a period of time even before the dinosaurs roamed the earth. Estimated to be some 270 million years old, these fossilized specimens offer an exciting window into the past. Similar in appearance to the palm tree, xaxim trees can still be found growing in Brazil today. However, they grow very slowly, averaging about 3 inches every 10 years. Featuring all natural color with no enhancement, xaxim is prized by fossil collectors across the globe.

Xaxim Polished
Xaxim Classification
Common Name Xaxim
Species Organic
Xaxim Optical Properties
Transparency Semitransparent - Semitranslucent
Dispersion Strength: None
Refractive Index 1.539-1.535
Birefringence 0.004
Optic Character Uniaxial
Optic Sign Positive
Polariscope Reaction Aggregate (AGG)
Fluorescence SWUV: Inert
LWUV: Inert
Pleochroism None
Xaxim Characteristic Physical Properties
Hardness 6.5-7
Specific Gravity 2.550-2.700 Typical:2.600
Toughness Excellent
Inclusions Xaxim's cellular appearance comes from the cross section structure of the fern.
Luster Vitreous, Greasy
Stability Good
Fracture Conchoidal, Granular
Cleavage None
Xaxim Chemistry & Crystallography
Chemical Name silicon dioxide (aka silica)
Chemical Formula SiO2
Crystal System Trigonal
Chemistry Classification Silicate

Xaxim Colors

  • Brown Xaxim Brown
  • Yellow Xaxim Yellow
  • Pink Xaxim Pink

Alternate Names

Fossilized Tree Fern, Agatized Fossil Tree Fern, Petrified Tree Fern

Countries of Origin



Normal care

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Tim Matthews


Tim Matthews

Tim Matthews is President and Chief Executive Officer of Jewelry Television® (JTV), as well as a member of the company's Board of Directors. He oversees and leads all aspects of the company's powerful omni-digital retail platform that uniquely specializes in fine jewelry and gemstones. His passion for business and gemstones has led him to become a recognized expert in the field of gemology. He is a life member of the Gemmological Association of Great Britain (Gem-A) and has earned Gem-A's highest degrees, the Gemmology (FGA) and Diamond (DGA) diplomas. He is also a Graduate Gemologist (GG) of the Gemological Institute of America (GIA) and has also completed GIA's Graduate Diplomas in Diamonds, Colored Stones and Pearls. Under his leadership, JTV has become the leader in the sourcing and selling of color gemstones and jewelry.

This page was created on June 27, 2014.

This page was last edited on October 24, 2019.