Permineralization: making a fossil

This resource teaches a way to for students and teachers to make fossils besides a mold or cast method. The materials are regular non-abrasive kitchen sponges and paraffin wax. The method describes could be adapted for all ages of students.  Fossils are remnants of once living things. One way fossils form is by permineralization. This is when the pore spaces of a bone are filled with mineral rich water and internal crystals begin to form. Eventually the whole bone becomes rock. The activity uses a sponge dipped in wax to imitate permineralization.

Standards & Objectives

Academic standards
GLE 0107.5.2
Recognize that some organisms which formerly lived are no longer found on earth.
GLE 0207.5.2
Draw conclusions from fossils about organisms that lived in the past.
GLE 0507.5.2
Analyze fossils to demonstrate the connection between organisms and environments that existed in the past and those that currently exist.
GLE 0807.5.6
Investigate fossils in sedimentary rock layers to gather evidence of changing life forms.
Alignment of this item to academic standards is based on recommendations from content creators, resource curators, and visitors to this website. It is the responsibility of each educator to verify that the materials are appropriate for your content area, aligned to current academic standards, and will be beneficial to your specific students.
Learning objectives: 

Students will be able to:

  • Make a comparison between their new wax sponge fossils and how mineral rich water crystallizes in the pore spaces of an organism's bones.
  • List the steps in how a bone becomes permineralized.
  • List organic body parts besides bones that can become permineralized.

Lesson Variations

Blooms taxonomy level: 
Differentiation suggestions: 

Add different colors of food coloring to multiple pots of boiling wax to simulate different kinds of mineral impurities. As directed by the students, dip different portions of the sponge fossil in different colors of wax. Alternatively, experiment with squeezing the sponge in one color and then just quickly dipping in another, in an attempt to simulate different internal permineralization.

Extension suggestions: 

Have the students cut out their fossils so that the leftover portion of the sponge is one intact piece. Use the internal portion of the sponge and the external border to illustrate the concept of molds and casts. Tour a museum or natural setting where various kinds and colors of permineralized fossils can be observed. Initiate and guide a discussion about the conflict created between souvenir hunters / rock hounds and paleontologists. Explain how permineralized fossils are exceeding in value to both groups of people yet for entirely different reasons. Invite the students to come up with ideas and policies that might satisfy both kinds of people's needs.


Helpful Hints

Materials needed:

Paraffin wax, 1 block (2" x 2" x 6") per 10 students 1 Nonabrasive household sponge per student (the bigger, the better) Heat source and a pot/pan for boiling paraffin wax Rubber gloves and safety goggles Tongs Permanent Markers and Scissors Various colors of food coloring (optional) * Stencils of different fossil shapes download file Wax paper