Label the plastic bag with the name and the location of the stream, mix the minerals back together again, pour them into the bag, and stick the magnet outside the bag so it is attached to the magnetite inside the bag and does not get lost. Back at school, separate out the magnetite by using the same procedure as step 11 and weigh the magnetic and nonmagnetic fractions. Look more carefully at the other minerals. Gold is a soft metal, softer than most other metals. Try a metal probe.
Gold has different colors because it mixes with different impurities.
Yellow gold is very, very heavy and will be with the gravel. Black gold is very heavy and will be with the sand. White gold is heavy and will be with the silt. Every stream carries a different suite of heavy minerals because streams have different rocks weathering in their watersheds. Many streams in the United States contain gold, especially in the East and the West.