Assignment 23 - Tourmaline, Peridot, and Zircon Flashcards
Which tourmaline variety is the most valued?
Paraiba tourmaline.
Which tourmaline variety makes a good emerald alternative?
Chrome tourmaline.
Which tourmaline colors are most popular?
Blue (Paraiba), Green/Blue (Chrome), Red/Pink (Rubellite)
Gems that show color zoning with two or more colors.
Parti-colored
A tourmaline, usually elbaite, with color zoning made up of a pink central zone surrounded by a green overgrowth.
Watermelon tourmaline
Trade term for a vibrant green tourmaline that’s colored by traces of vanadium, chromium, or both.
Chrome tourmaline.
Trade name for pink to red elbaite tourmaline.
Rubellite
Trade term for rare, expensive, vibrant green to blue or violet elbaite tourmaline, originally found only in Brazil’s Paraíba state.
Paraíba tourmaline.
How are tourmalines most commonly treated?
Heating and irradiation are the two most important tourmaline treatments.
Trade term for blue tourmaline.
Indicolite
What are the most important source of tourmaline?
Brazil and Africa.
Nigeria and Mozambique are Africa’s most economically important tourmaline sources.
What causes Paraiba tourmaline’s colors?
Traces of copper cause Paraíba tourmaline’s extraordinary colors.
Why is Paraiba tourmaline so expensive?
Paraíba tourmaline’s high prices result from a combination of attractive, highly saturated hues, extremely restricted supply, and strong demand.
Where is the world’s major source of gem-quality peridot?
Arizona supplies the world with rough for much of its commercial calibrated peridot.
Which sources produce the finest peridot?
Sources in Myanmar supply the world with most of its large, fine-color peridot.
What’s the safest cleaning technique for peridot?
Because peridot is sensitive to rapid temperature changes and chemicals, it’s best cleaned with warm water and mild detergent or soap.
Which treatment is used to produce blue zircon?
Heat treatment.
What is the most popular zircon color?
Heat-treated blue zircon.
What are zircon’s most distinctive gemological properties?
Colorless zircon’s strong double refraction easily distinguishes it from diamond and synthetic cubic zirconia.
A mineral that’s been broken down from a crystalline to a partly amorphous state by emanations from radioactive impurities.
Metamict.
Because metamict zircon’s physical and optical properties (specific gravity, double refraction, and refractive index) are so much lower than other types of zircon, they’re also described as “low zircons.”
What is peridot’s rating on the Mohs scale?
A. 2 to 3
B. 5 to 5.5
C. 6.5 to 7
D. 9
C. 6.5 to 7
What is peridot’s rating on the Mohs scale?
A. 2 to 3
B. 5 to 5.5
C. 6.5 to 7
D. 9
C. 6.5 to 7
Which countries produce the finest peridot?
A. Myanmar and Pakistan
B. Madagascar and Sri Lanka
C. Afghanistan and Cambodia
D. The United States and Brazil
A. Myanmar and Pakistan
Most gem tourmalines form in
A. marble.
B. limestone.
C. pegmatites.
D. metamorphic rock.
C. pegmatites.
Most fine chrome tourmaline comes from Kenya and
A. Brazil.
B. Tanzania.
C. Sri Lanka.
D. Madagascar.
B. Tanzania.
