Student Exploration: Mineral Identification
Vocabulary: crystal, density, hardness, homogeneous, luster, mass, mineral, streak, volume
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
1. Suppose you find a yellow piece of metal in a stream. How could you tell if it is real gold?
_To tell if it’s real gold check out it’s density, find it’s mass and volume, see if it’s luster
And how hard it is.__________________________________________________________
2. In the city a street peddler offers to sell you a diamond ring for thirty bucks. How could you test if the rock in the ring is a real diamond?
_To tell if it’s real diamond check out it’s density, find it’s mass and volume, see if it’s luster
And how hard it is.________________________________________________________
Gizmo Warm-up: Determining density
A mineral is a naturally formed crystal. You can identify a mineral by its properties. In the Mineral Identification Gizmo™, under Choose property to test, select Density.
1. Mass is the amount of substance in an object. Drag the mineral sample onto the balance.
What is the mass of the mineral? _69.6g_____
(Units are grams, g.)
2. Volume is the amount of space an object takes up. The volume is measured by how much the water rises in a graduated cylinder. Drag the mineral into the cylinder.
What is the volume of the mineral? __24.0 mL___ (Units are milliliters, or mL.)
3. Density is a measure of how “light” or “heavy” an object is for its size. To find the density of an object, divide the mass by the volume. (Calculators are recommended.)
What is the density of the mineral? ___2.9g/mL_____ (Units are grams per milliliter, g/mL. |Activity A: |Get the Gizmo ready: |[pic] | | |Under Property, select Appearance. | | |Mineral properties |Check that Sample A is on the screen. (If not, press Previous until sample A is | | | |there.) | |
Question: What properties allow us to identify minerals?
1. Observe: Minerals are made of atoms in a repeating pattern and often form crystals. The shapes of crystals can help identify the mineral. Luster is the way the mineral’s surface reflects light. There are many ways to describe luster, four examples are shown.
A. Describe the crystal shape of Sample A: It is like a hexagon and pyramid type of shape________
B. Describe its luster: _It is metallic with a little of glass on it _
C. What color is Sample A? _Gray_____________________
2. Calculate: Select the Density test. What is the density of Sample A? __2.6 g/mL _______
3. Measure: Select the Hardness test. Hardness is a measure of how easily a mineral can be scratched. It is measured on a scale of 1 to 10 called Mohs scale. If a mineral scratches a fingernail (hardness 2.5) but not a penny (3.5), its hardness is about 3.
A. Drag the mineral sample across each test object. Which objects are scratched?
Fingernail, penny, steel plate, and glass. __________________________
B. What is the estimated hardness of the mineral? _About 18____________________
4. Observe: Select the Streak test. The streak is the color of a material’s powder. You can observe the streak by rubbing the mineral across a tile called a “streak plate.”
Drag the mineral sample across the streak plate. What color is the streak? _The streak is Colorless and cannot be seen.
(Note: In some cases the streak is...