Background:
Diamonds are minerals that are valued for their durability, beauty, and rarity. They form deep in the earth under conditions of extreme heat and pressure, and are brought to the surface of the earth by the forces of volcanism and weathering. Generally, diamonds – and the rocks they’re found in – are very old. Studying diamonds, therefore, can help scientists reconstruct the processes that were central to the formation of the earth itself.

The physical properties of a diamond are determined more by the crystal structure of the diamond than by its composition – consider that diamond and graphite, despite their vastly different physical properties, are both composed of pure carbon. Every mineral is characterized a particular type of crystalline structure that is largely responsible for its physical properties.

These excerpts from the NATURE episode “Diamonds” demonstrate the characteristics of these rare gems, and explore the value they hold for scientists and the general public.

Suggested Focus Questions:

Clip 1: Diamonds Everywhere

1. What do diamonds symbolize in our society?
2. Explain the saying “a diamond is forever.” What are the different meanings of this phrase?

Clip 2: Diamond Formation

1. What materials and conditions are essential to the formation of a diamond?
2. How do you think artificial diamonds might be manufactured? What engineering problems might be involved in doing so?

Clip 3: Aging Diamonds?

1. How do diamonds get to the surface of the earth?
2. Why are diamonds valuable to scientists?
3. How do scientists determine the age of rocks and minerals? Why is it that “a diamond never grows old”?

Clip 4: Inclusion Conclusions

1. How hard are diamonds?
2. What is meant by the term “inclusion”?’
3. What can scientists determine by studying diamonds and their inclusions?

Downloadable QuickTime versions of the video segments:
(Note: To downoad a video, right-click on the video title and click “Save Link As…” or “Save Target As…” On a Mac, press the CTRL key and simultaneously click the mouse, then save the link.)
Clip 1, “Diamonds Everywhere”
Clip 2, “Diamond Formation”
Clip 3, “Aging Diamonds?”
Clip 4, “Inclusion Conclusions”

GRADE LEVEL: 9-11

TIME ALLOTMENT: Two to three 45-minute class periods

OVERVIEW: 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 common silicate 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).

SUBJECT MATTER: Earth Science, Mineralogy, Crystallography, Science and Society

LEARNING OBJECTIVES:
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.

STANDARDS and CURRICULUM ALIGNMENT:
National Science Education Standards

CONTENT STANDARD A: As a result of activities in grades 9-12, all students should develop

Abilities necessary to do scientific inquiry
Understandings about scientific inquiry

USE TECHNOLOGY AND MATHEMATICS TO IMPROVE INVESTIGATIONS AND COMMUNICATIONS.
A variety of technologies, such as hand tools, measuring instruments, and calculators, should be an integral component of scientific investigations. The use of computers for the collection, analysis, and display of data is also a part of this standard. Mathematics plays an essential role in all aspects of an inquiry. For example, measurement is used for posing questions, formulas are used for developing explanations, and charts and graphs are used for communicating results.

CONTENT STANDARD B: As a result of their activities in grades 9-12, all students should develop an understanding of STRUCTURE AND PROPERTIES OF MATTER.

• Bonds between atoms are created when electrons are paired up by being transferred or shared. A substance composed of a single kind of atom is called an element. The atoms may be bonded together into molecules or crystalline solids. A compound is formed when two or more kinds of atoms bind together chemically.
• The physical properties of compounds reflect the nature of the interactions among its molecules. These interactions are determined by the structure of the molecule, including the constituent atoms and the distances and angles between them.
• Carbon atoms can bond to one another in chains, rings, and branching networks to form a variety of structures, including synthetic polymers, oils, and the large molecules essential to life.

New York State Regents Core Curriculum Alignments:
Physical Setting: Earth Science Core Curriculum

Standard 1: Analysis, Inquiry, and Design
Students will use mathematical analysis, scientific inquiry, and engineering design in order to pose questions, seek answers, and develop solutions.

Key Idea 3. The observations made while testing proposed explanations, when analyzed using conventional and invented methods, provide new insights into phenomena.

Standard 2: Information Systems
Students will access, generate, process, and transfer information, using appropriate technologies.

Key Idea 1. Information technology is used to retrieve, process, and communicate information as a tool to enhance learning

Standard 4
Students will understand and apply scientific concepts, principles, and theories pertaining to the physical setting and living environment and recognize the historical development of ideas in science.

Key Idea 3. Matter is made up of particles whose properties determine the observable characteristics of matter and its reactivity.

Performance Indicators 3.1
Commencement: Students explain the properties of materials in terms of the arrangement and properties of the atoms that compose them

MEDIA COMPONENTS:
Video
NATURE: Diamonds, selected segments:

Clip 1: “Diamonds Everywhere”

A brief introduction the socio-economic value of diamonds

Clip 2: “Diamond Formation”

An expert describes the carbon composition of diamonds, as well as the conditions necessary for diamond formation.

Clip 3: “Aging Diamonds?”

Geological detectives use the ancient diamonds to learn more about the earth’s inner layers.

Clip 4: “Inclusion Conclusions”

Inclusions trapped within diamonds help geologists determine the age of diamonds and other information about where diamonds originate.

Access the streaming and downloadable video segments for this lesson at the Video Segments Page.

Web sites
The Virtual Museum of Minerals and Molecules:
Graphite crystal visualization
Diamond crystal visualization
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.

Silicate Structures
From the University of Wisconsin-Madison Web site:
Silica Tetrahedron

From the University of Arkansas Web site:
Olivine
Augite (Single Chain)
Hornblende (Double Chain)
Muscovite (Sheets)

From McGraw-Hill HIgher Education Online Learning Center Web site:
Animations of Silicate Structures

MATERIALS:
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 (PDF)(RTF)
• Tetrahedron Worksheet (PDF)(RTF)

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 (PDF)(RTF)
• Tetrahedron worksheet Answer Key (PDF) (RTF)

PREP FOR TEACHERS:
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.

PREP FOR STUDENTS:
Two days before the intended date of the lesson, hand out the Tetrahedron Cutouts and an envelope/plastic bag. Have students write their names on the envelope or bag. Instruct them to cut out their tetrahedrons at home, and bring the cutouts to class in the envelope/plastic bag the next day. Collect the envelopes/bags, and give students who forgot one more day to get them done. You may also hand out more sheets to students who are interested in cutting out a few more.

Next: Proceed to Activities.