Rock ID
Pumice--Igneous
This is the one that FLOATS. Note the texture. It is very coarse. It is actually glass. This is an Igneous Extrusive Rock.
Scoria--Igneous
Identify this one by texture. It feels very course like pumice. Doesn't float. It is an Igneous Extrusive Rock.
Obsidian--Igneous
This rock is Igneous Extrusive. It cooled so fast it has no visible mineral grains and is considered glass.
Gneiss--Metamorphic
This rock is a foliated metamorphic rock. Note the banding that goes through the rock from one side to the other.
Phyllite--Metamorphic
Note: from the side you can see sparkles.