1. ACTIVITY #13 DIAMOND DILEMMA

2. KEY CONCEPTS YOU WILL LEARN TODAY One way to gather data is through observations. Accurate and complete observations are important for making conclusions about the natural world. Scientists use common units of measurement to collect data. This system is known as the metric system A pure substance, such as a mineral, can be identified from observations and tests performed to determine its physical properties. These properties are based on the unique structure of the substance. Minerals are crystals that form naturally in the earth. They have characteristic properties, such as color, hardness, and a crystalline shape.

3. KEY VOCABULARY Crystal shape – the shape of a crystal sample of a mineral. Generally referred to by mineralogists as crystal habit. Luster – the shininess of a mineral. Property – the physical qualities of a material, such as color, hardness, state, density, and conductivity. Transparent/Transparency – the ability to transmit light clearly so that an object can be seen through a substance. Octahedron – a solid figure having eight sides.

4. DIAMONDS What is a diamond? Where do diamonds come from? What else could earrings be made from? Diamonds often look just like any other stones until they are cut and polished. Diamonds can come in a variety of different colors. How could you find out if earrings contain genuine diamonds?

5. ANALYSIS QUESTIONS 1a. Which of your observations were the same? All groups should have gotten the same answers: Color – colorless to light purple to pale gray Transparency – transparent Crystal shape – octahedron (8 sides) Luster – glassy, reflects some light Hardness – harder than copper, softer than glass b. Which of your observations were different? Your group might have differed on size 2. Every group received a sample of the same material. Compare your data with the rest of your group. Which observations do you predict will be the most useful in identifying the material? Why? Answers will vary 3. Do you think the material is a diamond? Support your opinion with at least three (3) observations from this activity and your data. Answers will vary