Assignment 23 - Tourmaline, Peridot, and Zircon

Question 1

Which tourmaline variety is the most valued?

Answer 1

Paraiba tourmaline.

Question 2

Which tourmaline variety makes a good emerald alternative?

Answer 2

Chrome tourmaline.

Question 3

Which tourmaline colors are most popular?

Answer 3

Blue (Paraiba), Green/Blue (Chrome), Red/Pink (Rubellite)

Question 4

Gems that show color zoning with two or more colors.

Answer 4

Parti-colored

Question 5

A tourmaline, usually elbaite, with color zoning made up of a pink central zone surrounded by a green overgrowth.

Answer 5

Watermelon tourmaline

Question 6

Trade term for a vibrant green tourmaline that’s colored by traces of vanadium, chromium, or both.

Answer 6

Chrome tourmaline.

Question 7

Trade name for pink to red elbaite tourmaline.

Answer 7

Rubellite

Question 8

Trade term for rare, expensive, vibrant green to blue or violet elbaite tourmaline, originally found only in Brazil’s Paraíba state.

Answer 8

Paraíba tourmaline.

Question 9

How are tourmalines most commonly treated?

Answer 9

Heating and irradiation are the two most important tourmaline treatments.

Question 10

Trade term for blue tourmaline.

Answer 10

Indicolite

Question 11

What are the most important source of tourmaline?

Answer 11

Brazil and Africa.

Nigeria and Mozambique are Africa’s most economically important tourmaline sources.

Question 12

What causes Paraiba tourmaline’s colors?

Answer 12

Traces of copper cause Paraíba tourmaline’s extraordinary colors.

Question 13

Why is Paraiba tourmaline so expensive?

Answer 13

Paraíba tourmaline’s high prices result from a combination of attractive, highly saturated hues, extremely restricted supply, and strong demand.

Question 14

Where is the world’s major source of gem-quality peridot?

Answer 14

Arizona supplies the world with rough for much of its commercial calibrated peridot.

Question 15

Which sources produce the finest peridot?

Answer 15

Sources in Myanmar supply the world with most of its large, fine-color peridot.

Question 16

What’s the safest cleaning technique for peridot?

Answer 16

Because peridot is sensitive to rapid temperature changes and chemicals, it’s best cleaned with warm water and mild detergent or soap.

Question 17

Which treatment is used to produce blue zircon?

Answer 17

Heat treatment.

Question 18

What is the most popular zircon color?

Answer 18

Heat-treated blue zircon.

Question 19

What are zircon’s most distinctive gemological properties?

Answer 19

Colorless zircon’s strong double refraction easily distinguishes it from diamond and synthetic cubic zirconia.

Question 20

A mineral that’s been broken down from a crystalline to a partly amorphous state by emanations from radioactive impurities.

Answer 20

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.”

Question 21

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

Answer 21

C. 6.5 to 7

Question 21

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

Answer 21

C. 6.5 to 7

Question 22

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

Answer 22

A. Myanmar and Pakistan

Question 23

Most gem tourmalines form in

A. marble.

B. limestone.

C. pegmatites.

D. metamorphic rock.

Answer 23

C. pegmatites.

Question 24

Most fine chrome tourmaline comes from Kenya and

A. Brazil.

B. Tanzania.

C. Sri Lanka.

D. Madagascar.

Answer 24

B. Tanzania.