GIA Diamond Formation, Mining, and the Diamond Market 2

Question 1

Which mineral is diamond composed of?

Accepted Answer

Carbon

Answer

Diamond is pure carbon atoms arranged in a crystal lattice structure called the diamond cubic.

Question 2

What is the approximate depth at which most natural diamonds form in the Earth's mantle?

Accepted Answer

100–200 km

Answer

Natural diamonds crystallize roughly 100–200 km below Earth's surface where extreme pressure and temperature conditions exist.

Question 3

Open-pit diamond mining is best characterized by:

Accepted Answer

Excavating a large terraced crater at the surface

Answer

Open-pit (or open-cast) mining removes ore in terraced steps from a large surface excavation, common in early-stage kimberlite mining.

Question 4

Which country is historically the first to have diamonds discovered and mined commercially in the modern era (mid-19th century)?

Accepted Answer

South Africa

Answer

The 1867 discovery of diamonds near the Orange River in South Africa launched the modern diamond mining industry.

Question 5

Alluvial diamond deposits are formed when:

Accepted Answer

Erosion transports diamonds from primary sources to riverbeds or beaches

Answer

Alluvial deposits result from weathering and erosion of primary kimberlite or lamproite, concentrating diamonds in sediment.

(GIA) Certified Diamonds Gemological Institute of America Practice Test