All terms in this list:
Granite: A group of igneous and plutonic rocks composed primarily of feldspar and quartz. Usually contains one or more dark minerals, which may be mica, pyroxene, or amphibole.
Basalt: A hard rock of varied mineral content; volcanic in origin, it makes up much of the Earth's crust.
Obsidian: a type of black glass produced by volcanos
Pumice: A light, porous type of pyroclastic igneous rock, formed during explosive volcanic eruptions when liquid lava is ejected into the air as a froth containing masses of gas bubbles.
Quartz: The most abundant mineral on the earth's surface, of chemical composition silicon dioxide, SiO2. It occurs in a variety of forms, both crystalline and amorphous. Found in every environment.
Slate: A fine-grained homogeneous sedimentary rock composed of clay or volcanic ash which has been metamorphosed so that it cleaves easily into thin layers.
Schist: Any crystalline rock having a foliated structure and hence admitting of ready division into slabs or slates.
Magnetite: A magnetic mineral, Fe3O4, one of the primary ores of iron. It has also been called lodestone.
Marble: A rock of crystalline limestone.
Graphite: A gray, crystalline, allotropic form of carbon that occurs as a mineral in some rocks and can be made from coke.
Sandstone: A sedimentary rock produced by the consolidation and compaction of sand, cemented with clay etc.
Shale: A fine-grained sedimentary rock of a thin, laminated, and often friable, structure.
Limestone: An abundant rock of marine and fresh-water sediments; primarily composed of calcite (CaCO₃); it occurs in a variety of forms, both crystalline and amorphous.