Properties of Minerals
Lesson 4 of 14
Objective: SWBAT use properties to identify minerals.
The Why Behind Teaching This
Unit 5 covers standards relating to Earth's Systems. It covers Standard 5-ESS2-1: Develop a model using an example to describe ways the geosphere, biosphere, hydrosphere, and/or atmosphere interact. Students will be learning the difference between each of the systems, and ways that each of the systems interact to help make Earth what it is today. The other standard covered is Standard 5-ESS2-2: Describe and graph the amounts and percentages of water and fresh water in various reservoirs to provide evidence about the distribution of water on Earth.
Modeling will be an important component of this unit. Students will be modeling layers of Earth, the water cycle, land forms, and more. The unit begins with an overview of all the systems, then each system is taught in isolation. As each new system is covered, how it depends on or interacts with the previous systems will be addressed. In addition to the end of unit assessment, there will also be a culminating activity where groups build a model to demonstrate how 2 of the systems interact. Connections to several previously covered standards will also be made throughout this unit.
This specific lesson covers standard 5-ESS2-1 because minerals make up part of the geosphere which will be important to know when discussing how the geosphere and biosphere interact later in the unit. Minerals are broken down by various processes and combine with animal matter to create soil. This connection will be important to note when identifying how the two systems impact each other.
The goal of this lesson is for students to be able to use properties to identify given minerals.
Students will demonstrate success by accurately identifying the six given minerals based on the properties tested.
Preparing For The Lesson:
- Two black minerals, one being magnetite, for each group
- A magnet for each group
- A copy of the Properties of Minerals Lab Sheet to put on the overhead.
- A copy of the Mohs Scale of Hardness for each group
- A ziplock bag with a sample of pyrite, quartz, talc, fluorite, hematite, and calcite in it.
- A streak plate for each group.
- A steel nail and copper penny for each group
- A copy of the Mineral Fact Sheet for each group
We will be comparing answer in this section so no additional materials are needed.
We have been learning about the layers of the Earth the past couple of days. The next couple of days, we will be learning about what makes up the crust of the Earth. Minerals are one thing found in the crust. Elements combine naturally, in variety of ways, to create different minerals. There are more than 3,700 known minerals. So how do scientists tell these minerals apart? They use properties.
I pass out two black minerals to each table group. I explain that one of the two minerals is magnetite. I ask them if they are able to identify which one is magnetite just by looking at them. They are not able to. I tell them that magnetite has a property that only a few minerals have. The students are able to guess that it is magnetic based on the name. I hand each group a magnet and tell them to figure out which mineral is magnetite. All groups test both minerals and hold up the one that is magnetic, which is magnetite.
Why Begin the Lesson This Way
I begin the lesson by having them identify magnetite because it is the only mineral that I have that is magnetic. It is easy to test and students can quickly identify magnetite. Magnetism is a property that the students will not be using in today's lab to identify minerals so I used it to begin the lesson so they would know that magnetism is another property that can be used to identify minerals.
What Other Properties Can Be Used to Identify Minerals
I place a copy of the Properties of Minerals Lab Sheet on the overhead so that the top portion is the only part showing. I explain each of the properties listed. Color is the appearance of the mineral: black, yellow, silver, transparent. Luster describes the way light is reflected off the mineral. Words such as dull/earthy, waxy, glassy, and metalic are used to describe luster. I show a mineral that is metallic and one that is earthy and ask students to describe the luster. They describe them using the correct terminology so I move on. If they were to struggle, I would show them more examples.
I continue on with streak: A streak plate is used to test streak color. I show a streak plate and use the sample of magnetite to model how to test the streak. I circulate to show all students the color of the streak left behind on the streak plate.
Hardness is the ability of a mineral to be scratched. The softest mineral is talc and the hardest mineral is diamond. Mohs Scale of Hardness is used to determine hardness, with one being the softest and ten being the hardest. I place the Mohs Scale of Hardness sheet on the overhead and point out the numbers, minerals, and common things used to test. All minerals high on the list can scratch all the listed minerals below them. For example, Quartz is a 7 on the hardness scale so it would be able to scratch any mineral that is a 6, 5, 4, 3, 2, 1. There are also some common materials used to test hardness. A fingernail is a 2.5, a penny is a 3.5, and a steel nail is 6.5. We will be using these items to test the hardness of our minerals today.
Cleavage is another property that can be used to identify a mineral. When minerals are hit with a hammer, they break in different ways, how they break can help determine the mineral. We will not be investigating this property today, but it is one they have to be able to identify. I circulate the room to show a mineral that has been broken so they can see that it breaks with a smooth side.
Completing the Lab
I reveal the bottom portion of the lab sheet so that students can now see the chart they will be completing during the lab. I hold up a Ziplock bag containing 6 minerals (talc, pyrite, fluorite, gypsum, hematite, and mica), a streak plate, a steel nail, a penny, a copy of Mohs Scale of Hardness, and 6 index cards labeled 1-6.
I explain that they will be working with their table group to complete the chart identifying the properties for each mineral in the bag. After they have the properties filled in, I give them a Mineral Fact Sheet. They match what they have recorded on the lab sheet, to the facts on the fact sheet, and identify each mineral.
I pass out a lab sheet to each student. As they glue it into their science notebook, I pass out the bag of minerals and supplies to each group. Each group takes out the index cards from the baggie and lays them out on a desk 1 -6. I hold up a greenish white colored mineral and instruct each group to find their mineral that matches and place it on the index card labeled as 1. I go through each of the six minerals so that each group has the same mineral for each number. This will help when we are checking them at the end to see which group has identified them correctly.
Groups begin recording their observations for color and luster, then begin testing the streak and hardness. I circulate to ensure that groups are doing one thing at a time, working together, and recording information as they go. The video of group testing mineral properties shows one group testing and recording the streak for a mineral. The video 2 of group testing mineral properties shows a group testing the hardness using the penny.
Using the Information Gathered to Identify the Minerals
Once groups have all of the information recorded for each of the six minerals, I provide them with the mineral fact sheet. They match what they have recorded on the lab sheet with what is on the fact sheet to determine which mineral is which. They record this in the mineral identification section of the lab sheet. I circulate while groups work on identifying the mineral to ensure they pay attention to all properties and not just use one to identify it. As you can see in the video of group determining mineral names, I draw their attention to properties that they may have missed to help them identify them correctly.
I wait to pass out the fact sheet until after they have recorded all of their observations from the lab because I do not want the fact sheet to guide their findings. I don't want them looking at the fact sheet as the answers they should have recorded, instead as a resource to match their answers to.
Sharing Our Findings
When all groups have completed the lab sheet, we check answers together. All groups should have found the following minerals:
- 1 - talc
- 2 - gypsum
- 3 - mica
- 4 - pyrite
- 5 - hematite
- 6 - fluorite
All groups were able to correctly identify pyrite, fluorite, mica, and hematite. I believe that pyrite, mica, and hematite were all easy for groups to identify because of the properties listed under the "other" category. For example, pyrite says fool's gold which is pretty easy to identify. Mica says it is in thin sheets which is also a unique characteristic. I think the property of luster is what was used by most groups to successfully identify fluorite. It says that it is glassy and after mica was identified, this was the only other mineral that would have been described as glassy.
2 out of the 5 groups got gypsum and talc mixed up. I think this is because the properties for these two are very similar. Both leave a white streak, are soft minerals, and are gray or white in color. I had these two groups feel both minerals again and identify which one feels greasy. This was a property listed under the "other" section of the lab sheet that should have helped identify talc.
Connecting This Lesson To Earth's Systems
To help students connect this lesson to the unit goal of how all four of Earth's systems interact, we have a short discussion to share ideas. Connections will be more clear as they learn more about the other systems. I ask the following questions:
- Which of Earth's systems would minerals belong to? The Geosphere
- How does what you learned today relate to the biosphere? One student says that humans are part of the biosphere and we use minerals to make things. Another student says he believes that plants use minerals to help them grow.
- Are their any ideas on how minerals might interact with the hydrosphere or atmosphere? The only idea that was shared was that different minerals probably form under water than those that form on land.