Ornamental tortoise shell is obtained from the carapace or shield of the hawksbill turtle found in the Malay Archipelago, West Indies and Brazil. The colour is mottled and mainly a translucent yellow with brown mottling.
Generally thicker shells are used to make jewellery which is brown in color with white spots.
Chemical Composition : Complex Protein (keratin)
Classification / Type :
Obtained from the carapace of a sea turtle.
Crystal System / Forms :
None. Amorphous.
Cuts & Uses :
Cabochons, used for inlay work, carvings, decorative combs and other items.
Dispersion : None.
Hardness : 2.5
Lustre : Oily to waxy.
Magnification :
Mottled sections show spherical spots of color. Larger numbers of dots give rise to deeper shades of color.
Optic Character :
A.G.G.
Pleochroism : None.
Refractive Index / Birefringence :
1.55 / Nil.
Simulants (with separation tests) :
- Most commonly plastic (bakelite).
- Dust and scrapings of tortoise shell are softened and moulded, also dyed to produce darker colors.
- Doublet – tortoise shell on a plastic base.
Sources :
Shell of turtles which are found at Indonesia, Indian Ocean, Malay Archipelago, Brazil and West Indies.
Specific Tests :
- Sectile and brittle.
- Thermoplastic nature which softens in boiling water; used to produce large sheets.
- Excessive heat darkens the color.
- Burnt hair odor.
Spectrum :
None.
Synthesis :
None.
Transparency :
Translucent to Opaque.
No comments:
Post a Comment