Xaxim | Gemopedia

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.
Alternate
Names
Fossilized Tree Fern, Agatized Fossil Tree Fern, Petrified Tree Fern
Colors
Tan, Cream, Brown, Orange, White, Gray, Black, Yellow, Red

Xaxim Classification

Common Name

Xaxim

Species

Quartz

Variety

Chalcedony

Colors

Tan, Cream, Brown, Orange, White, Gray, Black, Yellow, Red

Alternate Names

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

Gemstone Groups

Key Separations

RI, SG, appearance and fracture

Comments

Xaxim is estimated to be 270 million years old.

Xaxim Optical Properties

Transparency

Semitransparent - Semitranslucent

Refractive Index

1.539-1.535

Birefringence

0.004-0.004

Optic Character

Uniaxial

Optic Sign

Positive

Polariscope Reaction

Aggregate (AGG)

Fluorescence

SWUV: Inert
LWUV: Inert

CCF Reaction

Pleochroism

None

Dispersion

Strength: none

Comments

Xaxim Chemistry & Crystallography

Chemical Name

silicon dioxide (aka silica)

Chemical Formula

SiO2

Synthesis

Crystal System

Trigonal

Classification

Silicate

Nature

Natural

Crystallinity

Aggregate

Comments

Xaxim Characteristic Physical Properties

Hardness

6.5-7

Streak

Specific Gravity

2.55-2.7 Typical:2.6

Toughness

Excellent

Inclusions

Xaxim's cellular appearance comes from the cross section structure of the fern.

Luster

Vitreous

Stability

Good

Fracture

Conchoidal, Granular

Cleavage

None

Comments

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