Not A Rock (Synthetic Material)

Sandstone (Pebble/Cobble)

Sandstone (arenite is a more precise term for sandstone with less than 15% matrix; this specimen appears to be a lithic or quartz arenite)

Limestone

Calcium Carbonate (CaCO3)

Petrified Wood

Silicified Wood (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Conglomerate (or Breccia)

Clastic Sedimentary Rock (Conglomeratic)

Granite

Granite (Felsic Plutonic Rock)

Snowflake Obsidian

Volcanic glass containing Spherulitic Cristobalite (SiO2)

Basalt

Basalt (principally Plagioclase and Pyroxene)

Basalt with Quartz/Feldspar Inclusions

Amygdaloidal or Porphyritic Mafic Volcanic Rock with Siliceous Veining

Granite

Phaneritic Igneous Rock (Granite)

Quartzite

Quartzite (primarily SiO2)

Pink Granite

Granite (Felsic Plutonic Rock)

Mica Schist

Mica Schist (primarily composed of Muscovite, Biotite, and Quartz)

Serpentinite

Serpentinite (a rock composed predominantly of serpentine group minerals)

Coquina

Bioclastic Limestone (composed primarily of CaCO3)

Sandstone

Arenite (SiO2 based clastic rock)

Sandstone (likely Quartzose Sandstone)

Arenite (composed primarily of SiO2)

Granitic Quartz with Feldspar

Granite (composed primarily of SiO2 and KAlSi3O8)

Thunderegg (Agetized Geode nodule)

Rhyolitic Agate Nodule (SiO2 filling volcanic cavities)

Sandstone (Ferruginous)

Arenite (Fe2O3 staining)

Cinnabar in Quartz

Silicon Dioxide (Quartz, SiO2) with Mercury Sulfide inclusions (Cinnabar, HgS)

Sandstone (likely Quartzose Sandstone)

Arenite (SiO2 principal composition)

Chert (Nodular)

Microcrystalline Silica (SiO2)

Ferruginous Sandstone (Ironstone Conglomerate fragments)

Ferruginous clastic sedimentary rock (SiO2 cemented by Fe2O3)

Quartz (specifically Milky/Gray Quartz vein)

Silicon Dioxide (SiO2)

Sandstone

Arenite (primarily SiO2)

Sandstone (Ferruginous)

Clastic Sedimentary Rock (primarily SiO2 with Fe2O3 staining)

Serpentine

Serpentinite (Mg,Fe,Ni,Al,Zn,Mn)2-3(Si,Al,Fe)2O5(OH)4

Milky Quartz/Clear Quartz Cluster

Silicon Dioxide (SiO2)

Granite

Phaneritic Felsic Igneous Rock

Porphyritic Basalt (or Andesite) Pebble

Porphyritic Mafic Volcanic Rock

Granite Cobble

Phaneritic Felsic Igneous Rock

Sandstone (with Iron Staining)

Clastic Sedimentary Rock (primarily SiO2 with FeO(OH) impurities)

Sandstone (specifically Lithic or Quartz Arenite)

Arenite (composed primarily of SiO2)

Milky Quartz with Iron Inclusions

Silicon Dioxide (SiO2)

Quartz (Milky/Yellowish variety)

Silicon Dioxide (SiO2)

Quartzite

Metamorphic Quartzite (predominantly SiO2)

Sandstone

Clastic sedimentary rock (primarily Quartz and Feldspar)

Ferruginous Quartz Cobble

Silicon Dioxide (SiO2) with Iron Oxide inclusions

Sandstone

Arenite (primarily SiO2)

Limestone

Calcium Carbonate (CaCO3)

Sandstone (Ferruginous)

Arenite (with iron oxide cement)