We just started a Planet Earth unit in science and I am on the Types of Rocks unit. I got a worksheet after the first day and I know the answers to all the question except for this one because I couldn't find anything in my textbook;

Pumice is formed by gasses trapped inside of lava and has a light density, letting it float in water. Although, Scoria, which is formed by basaltic lava, is similar to Pumice in texture but does not float in water. Why do you think this happens? Give a possible explanation.

View the original article here