experiment to
make your own
fossils
Make your own fossils
What you will need:
A small shallow cardboard or plastic box (like a cut-off milk jug)
modeling clay or sculpting clay
plaster of paris
water and a small bucket to mix the plaster in
a knife or popcicle stick
cooking oil, shortening, or petroleum jelly
sea shells, leaves, chicken bones, your baby teeth... items to make your "fossil" from
How to make your fossil
1. Start off by making a smooth layer of clay in the bottom of your box. This clay represents the mud that the once-living organism fell on to.
2. Press in your shell or leaf, or anything once living, into the clay. You can also make a handprint or footprint, or pawprint if your pet will let you.
3. Mix the plaster of paris according to the package directions. Pour the thick soupy plaster over your clay in a thin layer, and let it harden. Be sure *not* to pour any leftover plaster down your sink, because it will stop up the drain!
4. Carefully remove the clay and hard plaster from the box. Scrape the clay off of the plaster, and you'll find a backwards impression of your fossil. This negative shape is like a mold fossil, where a dead animal or plant rotted away and left its shape in the mud, which later turned to rock.
5. To make a cast fossil (or a positive shape) from what you have done, coat the negative plaster piece with oil or shortening. Put this piece back in the box, fossil side up. Mix up some more plaster and pour a second layer over the first.
6. After the plaster hardens, remove it all from the box and separate the two pieces. Now you have a shape like the original living organism. If you would like to make it more realistic, you can paint your fossils to look like real ones.
Rockhounding Arkansas revised July 1999
© Rockhounding Arkansas 1998 http://rockhoundingAR.com