Mineral name: Calcite
Chemical formula: CaCO3
Physical properties: vitreous luster, hardness 3, white streak, three directions of cleavage forming rhombohedral shapes, fizzes in dilute hydrochloric acid.
Pick a different color for marking things made with calcite. Again, be sure you have plenty of dots.
Calcite is a primary ingredient in concrete and cement. Unless your classroom has brick walls, you may not see any concrete around you, but the foundation of the building is concrete, so put a dot on the floor. Concrete and cement also form many of the roads and bridges that are used for transportation, so calcite played a role in transporting everything in your room!
Calcite is used in the manufacture of iron and steel, so mark all iron or steel items, such as nails, screws, scissors, filing cabinets, staplers, paper clips, etc.
Calcite is used in paper making, to give the paper its bright, white color, and to make its surface smooth. Put a calcite dot on any writing paper, magazines, or books.
Calcite is a major component in fertilizers, so if you have any dots left, mark any fruits, vegetables, breads, etc. Since feed grown with fertilizers is fed to livestock, put a dot on any meat as well.