Fire Opal | Gemopedia

Unique and mysterious, fire opals are appropriately named for their fiery cherries, sunburst yellows and deep tangerines. Unlike many other opals, fire opal may not display play of color, and specimens that do are highly valuable. Mexico is one of today's primary fire opal sources, where this fiery gem has been treasured since the time of the Aztecs, who called it "gem of the bird of paradise" in their native language.
Alternate
Names
Precious Opal, Mexican Fire Opal, Brazilian Fire Opal, Cherry Opal, Gold Opal, Sun Opal
Colors
Yellow, Red, Orangy Red, Orange, Brown

Fire Opal Classification

Common Name

Fire Opal

Species

Opal

Variety

Fire Opal

Colors

Yellow, Red, Orangy Red, Orange, Brown

Alternate Names

Precious Opal, Mexican Fire Opal, Brazilian Fire Opal, Cherry Opal, Gold Opal, Sun Opal

Gemstone Groups

Key Separations

Appearance, RI and fluorescence

Comments

Fire opals RI is typically between 1.420 to 1.430, but some have been found to be as low as 1.370. Some stones might show play-of-color.

Fire Opal Optical Properties

Transparency

Transparent - Opaque

Refractive Index

1.45
Tolerance:(+0.020/-0.080)

Birefringence

Optic Character

NA

Optic Sign

Polariscope Reaction

Singly Refractive (SR) With ADR

Fluorescence

SWUV: Inert to moderate greenish brown
LWUV: Inert to moderate greenish brown

CCF Reaction

Pleochroism

None

Dispersion

Comments

Fire Opal Chemistry & Crystallography

Chemical Name

hydrated silicon dioxide

Chemical Formula

SiO2.nH2O

Synthesis

Crystal System

NA

Classification

Silicate

Nature

Natural

Crystallinity

Amorphous

Comments

Fire Opal Characteristic Physical Properties

Hardness

5-6.5

Streak

White

Specific Gravity

1.97-2.23 Typical:2.15

Toughness

Varies

Inclusions

Fire opal might have a cloudy appearance, show color zoning and have mineral or fluid inclusions.

Luster

Vitreous

Stability

Poor

Fracture

Conchoidal, Uneven

Cleavage

None

Comments

JTV on Google+
0 Items
My Wish List
Close
Item
Description
Qty.
Price


Estimated Order Total:
0
Total Due Today:
0
Close
Item
Description
Qty.
Price


Page of 1