2nd Grade Investigates Volcanic Rocks

2nd graders have begun their unit on rocks by observing the properties of three different igneous rocks: basalt, tuff and scoria. They described how the rocks felt, looked and even smelled! Then, we rubbed two of the same rocks together to see what happens.  The scoria and tuff both make rock dust while the basalt is such a hard rock that they just make scratch marks.

The next investigation had us putting the rocks, one type at a time, into a cup of water. What would happen? The gray basalt rock looked darker.  The red scoria had bubbles rise from it and it turned lighter in color.  The white tuff turned orange and even purple! There was also a steady stream of very small bubbles coming out of the tuff.  We also noticed that the rock dust made the water look "dirty".