I want to recreate the rock cycle using some item that can behave as a rock. The purpose of this is to get a point across to my students about how really there is a reason why the rock cycle is called rock cycle.

Most of them find rocks dull and uninteresting, so I was thinking about proving the rock cycle some other way. In a couple of hours researching I came across some surprising ideas, such as crayons, chocolates, wax, etc.

I wanted some feedback on how well you think I can get the point across of the rock cycle being a cycle. To them, thinking that something liquid, turn into solid, then gets destroyed, and mixed into something else, then melted again, is really hard to understand. Using something that does not take millions of years to form might be a better strategy I think.

  • 3
    $\begingroup$ You should take the "PS" part and post it as another question. It is actually interesting. $\endgroup$
    – Gimelist
    Mar 23 '15 at 5:29
  • $\begingroup$ Yes, I agree with @Michael here - consider turning your 'PS' statement into a separate question - it is something that does indeed sound very interesting! $\endgroup$
    – user889
    Mar 23 '15 at 8:58
  • $\begingroup$ My initial reaction was "wax". Not so sure about a biogeochemical cycle though. $\endgroup$
    – mtb-za
    Mar 23 '15 at 9:58
  • $\begingroup$ Chocolate might do a better job of erosion, although it would be by dissolution. I guess you could use a grater on wax? $\endgroup$
    – winwaed
    Mar 23 '15 at 13:29
  • 2
    $\begingroup$ What is the age range / grade of students you are teaching to? $\endgroup$
    – txpaulm
    Mar 30 '15 at 20:12

Here's an idea:

You can use dark chocolate and white chocolate. Use a grater to create "sediments": layers of alternating grated dark and white chocolate.

Now heat them up just before melting so you can stick them together with pressure, preserving the layered structure. Now fold them. There's your "metamorphic" rock.

Then, just melt the entire thing to create some chocolate-lava flows. Grate them again and eat!


If you want to stick to actual geological products rather that kitchen substitutes, you could demonstrate the properties of an extraordinary natural evaporite mineral, Mirabilite, Na2.SO4.10H2O. This is found in some of the East African salt lakes, amongst other places. Under dry conditions it dehydrates to a white powdery mineral, Thenardite. Under warm conditions it dissolves in its own water of crystallization. In some East African lakes, Mirabilite saturated water splashes on the beach by wave action, where it dries out as crystals. Then when it warms in the sun, it turns back to a liquid and drains back into the Lake. It's a phase change rather than a chemical change, but it gets across the message of cyclicity.


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