STUDENTS EXPERIMENT WITH “COOKING ROCKS”: APPLICATIONS TO UNDERSTANDING HEMATITE DIAGENESIS ON EARTH AND MARS
The basic experiment materials include goethite-cemented sandstone samples, oven access, and a digital camera to document before/after results. Students can evaluate how the formation of iron oxide minerals requires water. In the experiment, goethite (FeOOH) can transform to hematite (Fe2O3) by cooking the sandstone in a conventional oven (400+ degrees F) for an hour or more. Safety goggles and insulated gloves/potholders are recommended as a safety precaution. Students utilize the scientific method by outlining their hypothesis, methods/test, results, and conclusion. To document the change in mineralogy, before and after pictures are taken of the sample in the same position with a consistent scale.
To extend exploration, students can investigate: 1) analytical instrumentation (e.g., XRD or Vnir spectroscopy) to identify the before and after sample minerals; 2) additional experiments on whether adding more water after would produce further change; 3) aspects of time and how quickly change can occur; and 4) published literature to understand how Earth analogs and/or experiments helps scientists understand conditions of hematite formation on Mars. This easy recipe “rocks” with students.