Turquoise | Gemopedia

December's birthstone, turquoise was among the first gemstones ever mined. Stunning sky blues to stimulating sea greens have made turquoise one of the most popular color trends in jewelry history. Copper gives turquoise its range of blue hues while iron is responsible for its green colors. Treasured since the days of ancient Egypt, and the thousands of years since, turquoise is said to bring good fortune and happiness to those who wear it.
Alternate
Names
Turuqois
Colors
Light To Medium Blue, Greenish Blue To Green, Often Mottled With Brown, Dark Gray, Black Veins.

Turquoise Classification

Common Name

Turquoise

Species

Turquoise

Variety

Colors

Light To Medium Blue, Greenish Blue To Green, Often Mottled With Brown, Dark Gray, Black Veins.

Alternate Names

Turuqois

Gemstone Groups

Key Separations

The appearance of turquoise is a primary clue to its identity, especially if a recessed matrix is observed. Other key separations are its refractive index (using a spot reading or distant vision method), spectrum and possibly fluorescence.

Comments

Persian turquoise is an intense, robins egg or sky blue from the Nishapur district of Iran. Stones tend to have a low porosity and take a good polish. Persian turquoise has less dark veining than turquoise form other areas and might have white patches. It is considered to be the best quality of turquoise.Most American or Mexican turquoise is a by product of copper mining. Stones are generally light blue, greenish blue to blueish green and have can have a brown matrix and it is somewhat porous. The Sleeping Beauty Mine turquoise was light blue in color with very little veining. Egyptian turquoise has been depleted but antique stones will have a greenish blue to yellowish green color. Spiderweb turquoise has thin lines of matrix in web like patterns. Turquoise is a alternate birthstone for December.

Turquoise Optical Properties

Transparency

Semitranslucent - Opaque

Refractive Index

1.61-1.65

Birefringence

0.04

Optic Character

Biaxial

Optic Sign

Positive

Polariscope Reaction

Aggregate (AGG)

Fluorescence

SWUV: Inert
LWUV: Inert to weak greenish yellow

CCF Reaction

Pleochroism

None

Dispersion

Strength: none

Comments

Turquoise Chemistry & Crystallography

Chemical Name

hydrated copper aluminum phosphate

Chemical Formula

CuAl6(PO4)4(OH)8-5H2O

Synthesis

Crystal System

Triclinic

Classification

Phosphate

Nature

Natural

Crystallinity

Aggregate

Comments

Turquoise Characteristic Physical Properties

Hardness

5-6

Streak

White

Specific Gravity

2.38-2.86 Typical:2.74

Toughness

Varies

Inclusions

Turquoise often has brown, gray or black matrix that is sometimes recessed below the polished surface of the stone. Stone may contain pyrite or calcite inclusions.

Luster

Vitreous

Stability

Fracture

Granular

Cleavage

None

Comments

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