The soil composition in people’s backyards containsminute particles of magnetic material called rare-earth metals.Larger quantities of rare-earth metals lie in deep underground.The particles belong to a class of magnetic materials called ferrites that are formed in igneous (made by heat) rocks.Presence of particles in a soil compositionsuggests larger deposits of that metal nearby. In this project, the independent variable is the location of the soil sample, and the dependent variable is the resultant metallic material drawn from the soil.The constants include the magnet, the jar, the water and other conditions.
How many metallic particles are in your local soil?
- A horseshoe magnet
- Plastic wrap
- Twist-tie fastener
- Two wide-mouth jars (similar to 16 oz canning jars)
- Garden spade
- Paper towels
- Magnifying glass
- Soil samples (Choosing samples from several sites offers good comparisons and opportunities to conjecture about local geology)
- Kitchen or science lab scale
- Dig several spades of dirt from the backyard and set aside.
- Dig samples from other locations nearby like a popular park, a hiking trail, a golf course, etc.
- Label the samples.
- Cut a length of string and tie to the interior bend of the magnet so that the poles hang straight down.
- Cut a swath of plastic wrap and pull tight over the poles and up toward the string, fastening with a twist-tie.
- Fill both bottles with the same amount of clean water.
- Scoop about two inches of soil into one of the jars and stir to saturate.
- When the soil has almost settled, stir again, swirling it in motion.
- As the soil circulates, carefully dip the magnet into the water, down to the bottom and up to the top.
- Repeat slowly several times.
- Lift the magnet from the jar and move it to the clean water, slowly lowering it but keeping the fastener above water where it can be undone.
- The plastic will fall into the water, taking the particles with it. Attach another swath of plastic wrap to the magnet, fasten it and repeat process a couple more times.
- After a specified number of repetitions, pour the top portion of clean water out without losing the particles at the bottom.
- Empty the bottom of the jar onto paper towels that will dry, leaving the particles for examination.
- The magnifying glass will allow the particles to be seen more precisely.
- Record observations.
- The gathered particles can be weighed.
- Record the weight.
- Repeat the extraction of particles from other samples.
- Compare results from different locations.