TA Notes, Second Lab (Minerals), 1405 The Dynamic Earth, Fall 2017
This information is confidential, intended only for the Geology 1405 teachers
Revised 9:40 AM, 4 September 2017
Before the lab begins...
Check to be sure that the lab is in good condition, that the correct specimens are in the labeled boxes (students sometimes switch the specimens so that the labels and the specimens no longer go together), and that everything is ready for the lab.
Direct students to put their coats, backpacks, longboards or other paraphernalia that is not essential for the lab along the edges of the lab room. Keep the emergency exit clear.
As the students are coming into the classroom, consolidate them into groups of ~3-5 folks around a given table. When all the students are in the room, the groups should have approximately equal numbers of students in them.
The Teacher's Lab Outline
It is ESSENTIAL that you get through the introductory stuff with all deliberate speed
so that students have enough time to complete the lab activities.
- When the start time of the lab is reached...
- Tell them that the goals of this lab are...
- ...to help them learn how we can identify minerals based on their physical properties, and
- ...to help them prepare for the mineral and rock quiz that will occur in a few weeks.
- Tell them that we will be spending the whole period working on Activities 3.2 through 3.5 in the lab book.
- There are no extra copies of the activity sheets today. If a student does not have your lab book, they need to go to the bookstore and get one.
- It is OK and encouraged to touch/handle the specimens in this lab; however, they must be returned to the correct labeled cardboard box.
- Many of the specimens do not belong to Baylor. (Many belong to me.) All are to be treated with care. They can't take any home to use as study specimens.
- Quickly walk around the room and briefly point-out the labeled specimens, displays, and optional activities that students should make use of.
- Minerals of the Mohs hardness scale
- Mica and mica-like minerals: black biotite, clear muscovite, pink lepidolite, and green chlorite.
Tell them that these minerals have one direction of cleavage, and demonstrate (using muscovite or biotite) how these minerals can be separated into very thin sheets.
- Minerals like quartz, calcite, and fluorite that come in many different colors
- Sulfide minerals like galena, pyrite, chalcopyrite, bornite, and sphalerite.
These minerals provide good examples of a metallic luster.
Tell them that sphalerite smells like sulfur or match heads if it is scratched.
- Feldspar minerals: potassium feldspar, sodium- and calcium-plagioclase feldspar
- Elemental minerals made of just one type of atom: gold, silver, graphite (carbon), sulfur, copper.
A microscope is available if you want to look at the gold and silver specimens up close. Show them (generally) how to turn-on (and off) the microscope light and focus the microscope.
- Carbonate minerals calcite and dolomite that fizz in dilute hydrochloric acid.
Demonstrate how to drop a single drop of HCl on the specimen provided to observe the fizzing, and stress that they must rinse and dry the specimen in the sink after the experiment.
- A workstation where you can whack a halite grain with a hammer (gently) and produce pieces showing halite's 3 directions of cleavage.
Demonstrate by putting on the glasses, gently whacking a grain, and observing the result.
Reiterate that they need to wear safety glasses if they choose to do this optional activity.
- A display of fluorescent minerals.
Show them how to turn-on the UV fluorescent light (separate long & short wavelength switches) and how to cup their hands around their face so they can block the room light as they look into the box
- A display of other important or interesting minerals.
- The displays around the room are to be used along with information they read in the tables in the book to help them identify minerals.
- Briefly introduce what each group will be doing, using words like the following:
- In Activity 3.2, you will be considering a number of different characteristics of minerals that can be used to identify them
- In Activity 3.3, you will be determining minerals based on their density, both by using a method for assessing their relative densities by hefting specimens by hand and by measuring their density using their mass and volume.
Measuring density in Activity 3.3 involves the following steps:
In Activity 3.4, you will identify 15 minerals based on their observable characteristics and will use your observations along with information in the tables in the book to fill-in the activity sheet.
In Activity 3.5, you will consider the sources of economic minerals used to build a typical smartphone, and fill-in a corresponding table of information.
- turn-on the pan balance that is on the side counter adjacent to the activity area.
- place the white paper on the balance, and press the "zero" or tare button to reset the scale display to zero.
- gently put the dry mineral specimen on the paper, and record its mass in grams
- turn-off the pan balance and remove the paper.
- observe and record the water level in the graduated cylinder. Use the wash bottle to add water to the cylinder if necessary.
- attach the wire "cage" to the specimen, and gently lower it into the graduated cylinder. Observe and record the new water level.
- the difference between those two observed water levels is the volume of the mineral specimen
- calculate the density of the specimen by dividing the mass by the volume.
Then get them started on their activities.
Determine the timing of the activities, and write the switch times on the front and back boards
- Determine when the activities must finish so that the end-of-lab quiz can be administered.
- Determine the number of minutes between when you started the first activity and when you need to end the last activity
- Divide the total time in minutes by the number of activities (4 this week)
- Write the four end times (switch times) on the front and back whiteboards.
With 10 minutes left in the lab session (or when everyone has finished the activities), administer the post-lab survey. Announce that this post-lab survey is to be completed by each student individually, without assistance from any other student. It is a closed-book, closed-note quiz.
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