FAIRLY SIMPLE GEOLOGY EXERCISES
for
STUDENTS AND THEIR TEACHERS
Topics
Fairly Simple Mineral Identification
Fairly Simple Rock Identification
Easy (and Cheap) Crystal Growing
COOKIE MINING
Adapted by John J. Thomas
Purpose
This exercise is a good, basic, and practical activity that illustrates both what mining is and what the environmental effects of mining can be. The students will have the opportunity to find out what an ore is, will do the mining exercise, and then will try to restore the mined out land. They will be the mining company and will have to face the requirements of environmental law. Through this activity they will discover that being a good environmentalist is not an easy task.
Definitions
Ore - a material that can be economically mined. If you remove the material from the ground you can make a profit.
Waste Rock - all of the material that is left over after you remove the metal from the ore. It has no economic value at this time and so is dumped on a waste pile away from the ore bearing rock.
Mining - removing the ore from the non-ore rock.
Even today you can visit a mining area and observe the environmental havoc that is wreaked upon the countryside by the mining industry. Something as common as a gravel pit can at the least be an eyesore. In order to mine, one must separate the ore material from the waste rock, a process that blasts and/or moves everything in the mine, and removes 10-50% of the rock that was originally in the ground. In the past, the waste, 50-90% of the mine, was dumped out of the way of the mining activity in an area that was thought to be useless, frequently filling in a stream valley. The mine, where the ore and waste rock were removed, created a gigantic hole in the ground. One proposed mine in the Rocky Mountains would have removed an entire mountain and filled the adjacent valley. A popular mining technique in the coalfields of the Appalachians is to remove the top of a mountain to get at the coal underneath. During the mining and after the mine is abandoned, both the mine and the waste pile are usually devoid of vegetation. Rarely was any effort made to restore the land. Often it is so poisoned that nothing will grow on it. Since the 1970's the Environmental Protection Agency (EPA) has required that all mining lands must be returned to their original contours and the original vegetation.
The mine reclamation regulations have lead to some interesting environmental paradoxes. In many cases the original contours were not the best to control rainwater run-off and erosion. A simple aesthetic alteration would have been better, but the law does not allow changing the shape of the land surface. The most frustrating aspect of restoration is the vegetation. Mines are often developed in areas that have been significantly altered by the intrusion of people. A classic example is the coalfields in southeast Wyoming and northeast Colorado. Before the coal mines the area was severally overgrazed. The native vegetation was gone and the replacement plants were undesirable. But as each portion of the mines is rehabilitated, the vegetation that is regrown is the vegetation of overgrazing and not the native species. That's the law! It must be regrown with the vegetation that was there when the mine was started.
Materials
2 Paper towels or other clean materials. One on which the students can put the ore and waste rock the second for their fingers.
1 cookie for each student. The best, and easiest to use are the soft kind. Use chocolate chip, M&M, etc. Any cookie that contains a substance that can be separated from the cookie itself. Do be aware that some students may have dietary restrictions. Remember I usually give them two cookies.
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Simple Exercise
We will use chocolate chip cookies as the example. The teacher has to define what is an ore and what is waste rock. The ore is the chips. They are certainly the best part. The waste rock is the cookie. Be sure to tell the students not to eat the cookie. This has failed totally for me so I give them one cookie to eat and one to use for the exercise.
First mine the ore. Have the students break up the cookie so that they can remove all the chips as cleanly as possible. The minute they start to remove chips they will start to eat them. Tell them not to. They should make a pile of chips as they mine them. Remember that the waste rock (cookie) is not consumed so they should make a pile of the crumbs. When they are done, they should have a pile of chips (ore) and a pile of broken up country rock (waste rock). You might note that the ore (chips) still has some waste material (cookie) attached to it. It is very hard to get completely clean ore. The cleaning up is done in a processing plant.
Second, the ore is consumed. They may now eat the chips.
Third, the EPA has now ordered them to return the mine to its original shape. Tell them to put the cookie back together. This is an impossible task. The mining companies think it is impossible, too.
Quantitative Exercise
At each stage you can weigh the materials. Have the students weigh the cookie before they start to mine it. Then weigh the ore (chips) and the waste rock (cookie).
Starting Weight of Cookie ________________________
Weight of Chips _______________________
Weight of Cookie Crumbs ______________________
The weight of the ore (chips) divided by the original weight of the cookie is the percent ore in the mine.
Weight of Chips
Ore Percent = ———————————
Starting Weight of Cookie
Add the weight of the ore and the waste rock and see if it equals the weight of the original cookie. If it does not, there has been loss in the mining process. This loss would be similar to the loss due to erosion of the mine and the waste pile. The lost material pollutes the downstream area (the students' fingers and the floor).
Final Weight = Weight of Chips + Weight of Cookie Crumbs
Weight Loss = Starting Weight - Final Weight
Weight Loss
Percent Weight Loss = ———————
Starting Weight
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