This Collection contains 20 Types of Basic Rocks Specimens of Igneous, Sedimentary & Metamorphic Rocks Types. The Rock Specimens include Basalt, Gabbro, Granite, Obsidian, Pegmatite, Pumice, Anthracite, Gneiss, Marble, Quartzite, Serpentine, Slate, Chalk Lumps, Conglomerate, Diatomite, Flint, Lime Stone, Rock Salt, Sand Stone and Shale. Average sizes are 2 cm X 3 cm X 1.5 cm