Chapter 4 Key Concepts & Terms

Question 1

What type of deposits do most diamonds mined today come from?

Answer 1

Primary deposits

Question 2

Which type of deposits contain a higher percentage of gem-quality diamonds?

Answer 2

Secondary deposits

Question 3

Where do geologists focus their search for primary diamond deposits?

Answer 3

Cratons

Question 4

In which locations do geologists look for secondary diamond deposits?

Answer 4

Rivers, streams, and estuaries flowing away from cratons

Question 5

What do various surveys help geologists do in diamond exploration?

Answer 5

Narrow the search areas for diamonds

Question 6

What is required to assess potential diamond content in secondary deposits?

Answer 6

More bulk sampling

Question 7

What mining method removes diamond-bearing ore from a large opening at the surface?

Answer 7

Open-pit mining

Question 8

What is the most common method of underground diamond mining?

Answer 8

Cave mining

Question 9

What are the three main steps of diamond recovery?

Answer 9

• Sizing
• Concentrating
• Recovering

Question 10

How is sizing accomplished in diamond recovery?

Answer 10

Through a series of crushing and scrubbing

Question 11

What caused a shift in emphasis from secondary to primary diamond mining?

Answer 11

Improved technology

Question 12

Where is the largest known marine diamond deposit in the world located?

Answer 12

Namibia

Question 13

How many main regions produce the majority of diamonds today?

Answer 13

Four main regions

Question 14

Which continent is home to the world’s most diverse diamond sources?

Answer 14

Africa

Question 15

Which country is a top diamond producer in terms of both value and volume?

Answer 15

Botswana

Question 16

Which mine in Australia was once a major colored diamond producer?

Answer 16

Argyle mine

Question 17

What is Canada’s rank as a diamond producer in terms of value and volume?

Answer 17

Third-largest

Question 18

From what type of deposits are Brazil’s diamonds predominantly mined?

Answer 18

Alluvial deposits

Question 19

What percentage of the world’s rough diamond supply does Russia provide?

Answer 19

About a third

Question 20

What are alluvial deposits?

Answer 20

A deposit where gems are eroded from their source rock and then transported away from the source and further concentrated in rivers and streams.

Question 21

Define bulk sampling.

Answer 21

Large-scale character sampling of 5,000 to 10,000 tons of rock.

Question 22

What is cave mining?

Answer 22

An underground mining technique in which orebody is drilled beneath the surface, loosened, and collected as it falls.

Question 23

What does character sampling test?

Answer 23

The size, shape, clarity, and color of the diamonds in a deposit based on 500 tons of rock.

Question 24

What is dense media separation?

Answer 24

A recovery process that separates diamonds from lighter materials.

Question 25

Define drift in mining.

Answer 25

A horizontal tunnel drilled through a diamond pipe.

Question 26

What is geochemical testing?

Answer 26

An analysis that determines the chemical composition of a sample.

Question 27

What is a grease belt?

Answer 27

A mechanism that uses diamond’s affinity for grease to separate diamonds from other minerals.

Question 28

What are indicator minerals?

Answer 28

Minerals that form along with diamonds at great depths and are brought to the surface by the same kimberlite or lamproite.

Question 29

Define marine deposit.

Answer 29

A secondary diamond deposit created by rivers or streams carrying diamonds to the shoreline or ocean floor.

Question 30

What is microdiamond testing?

Answer 30

Screening for the presence of tiny diamonds in a sample.

Question 31

What does ore grade measure?

Answer 31

The concentration of diamonds in a deposit, measured by the amount of diamonds in 100 tons of earth removed.

Question 32

What is overburden?

Answer 32

Rock or soil that covers a diamond-bearing orebody.

Question 33

Define parcel in diamond mining.

Answer 33

A quantity of stones, sometimes of similar size and quality, packaged together for sale or storage.

Question 34

What is a primary deposit?

Answer 34

A deposit where gems are found in the rock that carried them to the surface.

Question 35

Define recovery in the context of diamonds.

Answer 35

A process used to separate diamonds from host rock or sediments.

Question 36

What is a secondary deposit?

Answer 36

A deposit where gems are found away from their primary source.

Question 37

What is a shaft in mining?

Answer 37

A vertical tunnel drilled in stable rock near the pipe to provide access for personnel, equipment, supplies, and ventilation.

Question 38

What is sizing in diamond processing?

Answer 38

A process used to reduce diamond-bearing ore to smaller, more manageable sizes.

Question 39

What does X-ray separation utilize?

Answer 39

A recovery method that uses X-rays to detect diamonds and an air jet to remove them from the ore.