Pink diamonds

This exercise is a part of Educator Guide: Pink diamonds and Demystifying myths with data / View Guide
three diamonds in varying shades of pink
Diamonds can become pink when powerful forces inside the Earth distort their crystal lattices, changing how the gemstones reflect and transmit light.Murray Rayner, Rio Tinto

Directions for teachers:

To engage students before reading the article, have them watch this video to learn where diamonds come from. Then answer the “Before Reading” questions as a warmup in class or for homework. Next, ask students to read the online Science News Explores article “To get diamonds perfect for Barbie, make and break a supercontinent.” For a higher reading level, students could also read the Science News article version “To form pink diamonds, build and destroy a supercontinent.” Next, have them answer the “During Reading” questions. As an optional extension for deeper analysis, have students discuss the “After Reading” questions.

Directions for students:

Watch this video to learn about diamond formation, then answer the “Before Reading” questions as instructed by your teacher. Next, read the online Science News Explores article “To get diamonds perfect for Barbie, make and break a supercontinent”  and answer the following questions as directed by your teacher.

Before Reading:
1. Compare the physical properties of pencil lead — called graphite — with diamonds. Come up with two differences.

Student answers will vary. Graphite is a dull gray color, while diamonds are generally colorless, or clear, and sparkle in light. Diamonds are very hard structures that cannot be easily broken. To write on paper, graphite smears off. So it must be softer than diamonds.

2. Despite these differences in physical properties, both graphite and diamond are made of carbon atoms bonded together chemically. Consider what might cause graphite and diamond to exhibit such different properties. Come up with a potential explanation for those differences.

Answers will vary. Possible answers may guess that the materials have different arrangements of their atoms or have perhaps have different types of chemical bonds.

3. According to the video, what two conditions led to the creation of diamonds at Earth’s surface?

Intense heat and pressure about 160 kilometers below Earth’s surface forced the carbon atoms into a tetrahedral crystal structure. Then volcanic eruptions blasted the diamonds up to Earth’s surface quickly — so quickly that the carbon atoms couldn’t shift back into another crystalline structure.

During Reading:
1. On which continent do the natural pink diamonds described in this article occur most frequently?

They occur most frequently in Australia.

2. The Argyle mine occurs along a rift zone. In one sentence, explain how this rift zone formed. Include the name of “Earth’s first true supercontinent” in your explanation.

The rift zone formed from the breaking apart of the Earth’s first true supercontinent, called Nuna.

3. What form does carbon usually take when it crystallizes on Earth’s surface? Give one example of an everyday tool that makes use of this substance.

Carbon on Earth’s surface tends to form as graphite. An everyday tool that uses graphite is a pencil.

4. How might gemstones that form far below Earth’s crust “hitch a ride” to the surface?

Gemstones might escape to the surface by hitching a ride with rising magma.

5. What is the relationship between kimberlite pipes and most diamonds?

Most diamonds appear in these pipes.

6. How might changes in its atomic structure change a diamond’s appearance?

Diamonds typically have no color. But colors can emerge if the 3-D arrangement of atoms gets altered.

7. Generally, does lamproite form deeper, more shallow or at the same depth as kimberlite? In general, which material tends to contain more diamonds

Generally, lamproite forms at shallower depths than kimberlite and tends to contain less carbon in the form of diamonds.

8. What geological event likely brought about the formation of the natural pink diamonds? What event likely allowed those pink diamonds to rise to the surface?

Scientists believe the collision of ancient continents that resulted in the formation of Nuna brought about the formation of the natural pink diamond. Millions of years later, when those continents drifted apart, that likely allowed the pink diamond to escape to the surface.

After Reading:
1. In the 1980s, scientists tried to determine the age of rocks in the Argyle mine. However, the scientists were skeptical of their results. (Being skeptical means you are not easily convinced of something, or perhaps you have doubts.) Years later, different scientists would use a different technique to test the Argyle rocks and produce different results than the scientists did in the 1980s. To what extent do you feel that skepticism can be valuable in science? If scientists in this article had not been skeptical, how might that have changed the outcome of this study?

Answers about scientific skepticism will vary. A possible answer might be that skepticism is valuable in science and that if the scientists in this study had not been skeptical of the rock’s age, they might not have uncovered the true origin of the pink diamonds.

2. How might the findings described in this article allow us to identify other places in the world where pink diamonds may reside? Imagine you’re going on a quest for diamonds. Where would you begin?

These findings revealed a type of geological history that could encourage natural pink diamonds to form. If we found other places in the world with a similar geological history, we might locate new deposits containing these crystals.