12 well known rocks and their types (Igneous, Sedimentary, Metamorphic) include rocks like, Basalt, Gneiss, Marble, Granite, etc.
Basalt - Igneous Gneiss - Metamorphic Marble - Metamorphic Granite - Igneous Sandstone - Sedimentary Shale - Sedimentary Slate - metamorphic Limestone - Sedimentary Quartzite - Metamorphic Coal - Sedimentary Dolomite - Sedimentary Rhyolite - Igneous
I agree with the previous post, but if you need to add images to your report, this website has free images as well as explanations of the rocks. gccweb.gccaz.edu/earthsci/imagear.
those white dots are pearlite and they are a volcanic substance. In your potting soil they help to keep it aerated, or loose.
Perlite. Mix it in with soil for container plantings and your containers won't weigh a ton and the soil will retain moisture longer . . . a little longer.
I think it's perlite. It's a type of material used for potting soil that is very effective at holding in moisture.
