Turquoise

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Natural Turquoise Gemstone

Refractive Index : 1.650 – 1.610 (1.61 spot)

Optical Characteristic : AGG

Specific Gravity : 2.76 (+0.14 – 0.36)

Formula : CuAI6(PO4)4(OH)8.5H2o +Fe.

Crystal System : Triclinic

Variety/Species : All

Species/Group : Turquoise

Birefringence : none

Dispersion : N/A

Hardness : 5 to 6

Toughness : poor to good

Ultrasonic : Never

Steam : Never

UV Long : Inert to weak

UV Short : Inert

Pleochroism : None

Strength : N/A

Pleochroism Colors : None

Heat : Avoid heating

Acids : Attacked by acids and/or chemicals

Light : stable

Polish Luster : waxy to vitreous

Fracture : conchoidal or granular

Fracture Luster : waxy to dull

Clarity Type : N/A

Tones : N/A

Saturations : N/A

Cause of Color : Blue – copper, Green – copper and iron

Enhancements :

Plasctic Impregnation, sometimes with a colorant added - This treatment can be detected by the combination of color and low SG (strong indication), hot point, infrared spectrum, magnification. This treatment is quite stable.

Wax Impregnation, Dyeing with liquid black shoe polish – This type of treatment imitates matrix. This dye is easily removed with an acetone-soaked cotton swab.

Backing thin pieces with an epoxy – If unmounted, always identfiable by visual appearance.

Filling cavities with metal loaded epoxy (usually a yellow pyrite color) – This treatment fills up the cavities and imitated pyrite inclusions. This can be detected by magnification, hot point, color and luster.

Surface coating with lacquer, epoxy etc – This is done to add color or to seal underlying dye or paint

Cleavage : None

Color Range : Medium to light blue, greenish blue, green, bluish green

Transparency : Semitranslucent to opaque

Phenomena : None

Separations : Turquoise from-
Synthetic turquoise : magnification, spectrum(possibly)

Dyed howite : appearance, color filter, SG(possibly), spectrum

Variscite : color filter, RI, appearance, spectrum, SG(possibly)

Amazonite : RI, apperance (structure), cleavage, epectrum

Glass : fracture luster, magnification, RI(possibly), spectrum(possibly)

Plastic : SG, magnification, RI(possibly), spectrum(possibly)

Serpentine : RI, hardness(possibly), spectrum

Pectolite : apperance (structure), spectrum, birefringence, fluorescence

Prosopite : RI, SG, spectrum

Identifying Characteristics and information
Matrix is often present
Natural Turquoise is part of a series to chalcosiderite

Spectral Data
Line at 4320, Weaker line at 4200. Possibly a Weaker yet line at 4600

Trade Names and Misnomers
American Turquoise
Callaite
Chalcosiderite
Egyptian Turquoise
Mexican Turquoise
Persian Turquoise
Spiderweb Turquoise
Turquoise

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Turquoise