Diamonds 4 — How Diamonds Form

Question 1

Most of the world’s kimberlite pipes

A.	are located close to large cities.
B.	are being mined for diamonds at the present.
C.	do not contain diamonds in profitable quantities.
D.	are believed to contain great quantities of diamonds.

Answer 1

C. do not contain diamonds in profitable quantities.

Question 2

Before arriving at the earth’s surface, diamonds might remain in the mantle for as long as a few

A.	days.
B.	hours.
C.	hundred years.
D.	hundred million years.

Answer 2

D. hundred million years.

Question 3

Scientists have found that diamonds form in two types of rocks, called

A.	marble and shale.
B.	sandstone and schist.
C.	peridotite and eclogite.
D.	kimberlite and lamproite.

Answer 3

C. peridotite and eclogite.

Question 4

The three main components of the earth are the crust, mantle, and

A.	core.
B.	center.
C.	stratosphere.
D.	subduction zone.

Answer 4

A. core.

Question 5

The large, stable parts of the earth’s continental crust are called

A. plates.
B. islands.
C. shields.
D. cratons.

Answer 5

D. cratons.

Question 6

During emplacement, if diamonds are exposed to high temperature along with decreased pressure for a long period, they will

A.	melt.
B.	explode.
C.	vaporize.
D.	convert to graphite.

Answer 6

D. convert to graphite.

Question 7

The proper environment for diamond formation includes the right temperature, pressure and

A.	molten lava.
B.	indicator minerals.
C.	the availability of carbon.
D.	the presence of trace elements.

Answer 7

C. the availability of carbon.

Question 8

Subduction occurs when

A.	volcanoes erupt.
B.	mountains collide.
C.	tidal waves sweep over landmasses.
D.	two of the earth’s crustal plates collide.

Answer 8

D. two of the earth’s crustal plates collide.

Question 9

The first authenticated diamond discovered in South Africa is named the

A.	Eureka.
B.	Cullinan.
C.	De Beers.
D.	Star of Africa.

Answer 9

A. Eureka.

Question 10

How far beneath the earth’s surface do diamonds form?

A.	15 to 30 miles (25 to 50 kilometers)
B.	30 to 50 miles (50 to 75 kilometers)
C.	50 to 90 miles (75 to 140 kilometers)
D.	90 to 140 miles (140 to 220 kilometers)

Answer 10

D. 90 to 140 miles (140 to 220 kilometers)

Question 11

The correct conditions for diamond formation exist under

A.	cratons.
B.	volcanic ash.
C.	oceanic crust.
D.	large mountain ranges.

Answer 11

A. cratons.

Question 12

Diamond and graphite are both made of

A.	carbon.
B.	helium.
C.	oxygen.
D.	nitrogen.

Answer 12

A. carbon.

Question 13

Diamond is hard and graphite is soft because of the difference in

A.	their atoms.
B.	their transparency.
C.	their chemical formulas.
D.	the way their atoms fit together.

Answer 13

D. the way their atoms fit together.

Question 14

Diamonds were delivered to the earth’s surface as recently as

A.	20 billion years ago.
B.	20 million years ago.
C.	1 million years ago.
D.	10,000 years ago.

Answer 14

B. 20 million years ago.

Question 15

The deep vertical formations through which diamonds traveled to the surface are called

A.	drifts.
B.	pipes.
C.	cratons.
D.	alluvials.

Answer 15

B. pipes.