The rarity and unique physical properties of diamonds have earned them an important and valuable place in our society. The Nature episode “Diamonds” investigates the origins of this brilliant gemstone, as well as how it is mined and sold.
In this lesson, students will explore the characteristics of diamonds, and begin building an understanding of their formative environment, the resulting crystal structures and the physical properties of earth materials. Students will also be introduced to the silica tetrahedron and the silicate minerals, build physical models of silicate structures, and determine the physical properties of several commonsilicate mineral samples.
Prior to commencing this lesson, students should have already been introduced to the concepts of minerals and the physical properties used to identify them (i.e. luster, hardness, and cleavage/fracture).
Students will be able to:
- Determine some physical properties of minerals;
- State and illustrate, with examples, that the physical properties of minerals are a function of their crystal structures;
- Connect the scientific significance of diamonds to its cultural and historical significance;
- Construct simple models of olivine, pyroxenes, amphiboles, and micas using 3 dimensional silicate tetrahedron models.
Two to three 45-minute class periods
- Diamonds Everywhere QuickTime VR Video
- Diamond Formation QuickTime Video
- Aging Diamonds? QuickTime Video
- Inclusion Conclusions QuickTime Video
For each student:
- Tetrahedron Cutouts
- Envelopes or plastic zip-top bags for student tetrahedron cutouts
- NY Earth Science Reference Tables (ESRT) or a copy of pages 8-9 of the ESRT
- Diamond Discussion Worksheet
- Tetrahedron Worksheet
For each group of 3-4 students:
- A mineral testing kit consisting of one sample each of olivine, augite, hornblende, and muscovite mica, one streak plate, and one glass hardness testing plate
- Envelopes or zip-top plastic sandwich bags to hold mineral testing kits
- Glue sticks or paste
- Paper and pens
- One computer with broadband internet access and updated browser installed
For the Classroom:
- One computer for the teacher with a digital projection system
- Diamond Discussion Worksheet Answer Key
- Tetrahedron Worksheet Answer Key
The Virtual Museum of Minerals and Molecules:
This site features 3-D crystal models for graphite and diamonds.
Please Note: These images require a plug-in download. See instructions under Prep for Teachers.
From the University of Wisconsin-Madison Web site:
From the University of Arkansas Web site:
Before The Lesson
Prior to teaching this lesson, you will need to:
Preview all of the video clips and Web sites used in the lessonload the video clips used in the lesson to your classroom computer, or prepare to watch them using your classroom’s Internet connection.
Bookmark the Web sites used in the lesson on each computer in your classroom. Using a social bookmarking tool such as del.icio.us or diigo (or an online bookmarking utility such as portaportal) will allow you to organize all the links in a central location.
The ideal setup for this lesson would be a workstation or laptop at a small lab table or station for each group of 3 or 4 students. If that setup is not possible, read through this lesson and decide how best to make it work in your classroom situation.
Test student workstations for compatibility with jmol scripts by logging on to the Virtual Museum Web pages (newer computers and updated browsers should support jmol). If yours does not, ask your technical staff to make the proper adjustments and test the computers yourself before attempting this lesson.
Make copies of all print materials as outlined in the materials section.
Copy, cut-out and assemble a few tetrahedron models yourself, noting best practices for assembly to share with your students.
Prepare a mineral kit for each group of 3 or 4 students containing a sample each of olivine, augite (pyroxene), hornblende (amphibole), biotite or muscovite (mica), a streak plate, and a glass hardness testing plate.
Part I: Introductory Activity
1. Begin by asking students write down the first thing that comes to mind when they think about diamonds. Then ask the students to write down any other information they know about diamonds. Lead a discussion that allows students to share their answers with each other. Record some of the answers and reactions to diamonds on the board.
2. Provide students with a focus for media interaction, asking students to record some of the different things a diamond can evoke and symbolize, according to the videosegment. Play segment 1, Diamonds Everywhere QuickTime VR Video. Lead a discussion that allows students to share their answers and compare them with their previous answers. Be sure to address the cultural and monetary value of diamonds.
Part II: Learning Activity
1. Tell students that in this lesson, they are going to learn a little about where and how diamonds are formed, and what makes them both rare and valuable. Distribute the Diamond Discussion Worksheet to your students.
2. Provide students with a focus for media interaction, asking students to use their Diamond Discussionworksheet to record the conditions necessary for the formation of diamonds, as well as the composition of diamonds. (Students should complete Questions # 1-2 on the organizer.) Play segment 2, Diamond Formation QuickTime Video. Lead a discussion about the extreme heat and pressure required for the formation of diamonds and their carbon composition. Emphasize that carbon is one of the most abundant elements in the universe. Carbon is a major component of graphite, limestone, marble, coal, petroleum and natural gas. Carbon occurs in all organic life and is important to many organic compounds.
3. Explain to students that graphite and diamonds are both examples of pure carbon atoms, but that they each have a different crystalline arrangement. Direct students to visit the following Web pages from the Virtual Museum of Minerals and Molecules:
Provide for the students a focus for media interaction, instructing students to manipulate the 3-D crystal structures, and read through the description of each mineral. Ask students to record a description of each structure on their Diamond Discussion worksheet, and provide information as to why the diamonds structure is so strong. (Students should complete Questions # 3-5 on the organizer.) See the Diamond Discussion Worksheet Answer Key for suggested student responses. Lead a discussion with students about their answers, and how the arrangements of the atoms determine the physical properties of the mineral.
4. Provide students with a focus for media interaction, asking them to determine where diamonds are formed. What kind of information can diamonds provide to geologistsstudying this location? (Students should complete Questions # 6-7 on the organizer.) Play segment 3, Aging Diamonds? QuickTime Video.Lead a discussion with students about their answers. Be sure to point out that while diamonds are formed deep beneath the surface of the earth, most other rocks are formed in the earth’s crust. This is what makes diamonds so important for geologists interested in learning about the deep interior of the earth.
5. Distribute pages 8-9 of the NY Earth Science Reference Tables (ESRT). Ask students read through the chart and be prepared to discuss what information is presented on the chart in pages 8-9. Direct students to the timelinealong the left column of the page, and briefly allow students to share different elements of the chart. Ask students to mark a guess on the timeline as to the age of diamonds.
6. Provide students with a focus for media interaction, asking students to determine what allows geologists to identify the age of a diamond, how old diamonds are, andwhat other information this resource offers, and record their answers on the Diamond Discussion worksheet. (Students should complete Questions # 8-10 on the organizer.) Play segment 4, Inclusion Conclusions QuickTime Video. Lead a discussion with the students about their answers. Define “inclusions” with your students: “inclusions” are bits of surrounding minerals that are captured within diamonds. Discuss how inclusions allow geologists to determine the age of the diamond. Inclusions alsooffer geologists the opportunity to study materials that can only be formed deep within the inner core of the earth.
7. Ask students to look back at page 8 of the ESRT and indicate, using a different marking, the actual age of diamonds. (Diamonds are 2-3 billion years old!) Lead a discussion with your students about the inaccuracy or accuracy of their guesses, and what led them to make their decisions.
Part III: Culminating Activity
1. Remind students of the arrangement of atoms within a diamond and how this arrangement determines the physical properties of the mineral. Tell students that the arrangement of atoms within many other minerals also determines their physical properties.
2. Project the image of the silica tetrahedron, and explain that this arrangement of four oxygen atoms surrounding a silicon atom is the basic building block of many common minerals. Provide students with a focus for media interaction, asking students to describe the shape of each side of the silica structure, and count the sides (each side is an equilateral triangle, and there are 4 sides). Explain that a four-sided regular solid is called a tetrahedron (tetra = 4 and hedron = sides), that the oxide of silicon forms a silica tetrahedron, and they are arranged in very specific patterns in different silicate minerals.
3. Project the animation of silicate structures. Provide students with a focus for media interaction, asking students to describe the various patterns illustrated in the animation. Lead a discussion with the students about their answers (the atoms of the silicone oxygen tetrahedron bond with each other in single chains, double chains, sheets, and framework arrangements).
4. Distribute the envelopes/bags of previously prepared tetrahedron cut-outs and a glue stick to every group of 3 or 4 students. Demonstrate for the class how to fold the tetrahedron cut-out into a 3-dimensional tetrahedron and glue it together. Explain that these paper models illustrate the basic atomic structure of the elements that compose many common minerals. Using these models, students willconstruct examples of the crystalline structure for four different types of minerals. Instruct students to make as many 3-dimensional tetrahedrons as they can with the cutouts they have prepared.
5. Distribute the mineral kits of olivine, augite, hornblende, and muscovite to each group of students. Direct them to the following Web pages:
Augite (Single Chain)
Hornblende (Double Chain)
Provide students with a focus for media interaction, instructing students to construct models of each structure as seen on the website. After constructing the model of each mineral and matching it with the sample rock, ask students to sketch it on the Tetrahedron Worksheet. Then, using the sample minerals, they should determine the physical properties of the sample and record that information on the Tetrahedron worksheet as well.
6. Lead a discussion with students about the different minerals they have just constructed and the various properties they possess. Allow students to share their drawings and models with each other.
7. Collect the Tetrahedron Worksheets as an assessment of student work. The Tetrahedron Worksheet Answer Key is provided.
Direct students to visit the Web sites about diamonds listed below. Provide students with a focus for media interaction, asking students to look for two examples ofdiamonds in folklore and superstitions, as well as examples of the role of diamonds in art. Students should record this information on their Diamond Discussion worksheet. Lead a discussion between students so they can share their answers (see Answer Key for possible answers). Remind students of what the discussed in the introductory activity andhow the cultural significance of diamonds is as valuable and extensive as the scientific.
Everything from diamond mining to diamond lore, this site offers fascinating look into the many facets of the world of diamonds.
This site explores the history of the diamond, the craft of diamond cutting, and the gem’s role in the art world.
Help students build a display of their models and drawings in the classroom.
Invite a local jeweler or gemologist to your classroom to discuss their career path and understanding of diamonds.