Not A Rock

Sandstone (with Iron Siderite Concretion)

Arenite with Ironstone Concretion (FeCO3)

Chert (Chalcedony/Agate)

Microcrystalline Quartz (SiO2)

Pink Granite

Granite (Phaneritic igneous rock)

Granodiorite

Granodiorite (phaneritic intrusive igneous rock)

Olivine Peridotite

Peridotite (comprising Olivine (Mg,Fe)2SiO4 and Pyroxene)

Sandstone (likely Arkosic)

Arenite (SiO2 with KAlSi3O8)

Limestone (Weathered)

Calcium Carbonate (CaCO3)

Scoria (Lava Rock)

Extrusive Igneous Scoria (Vesicular Basalt)

Basalt

Basalt (Mafic Extrusive Igneous Rock)

Clear Quartz / Rock Crystal

Silicon Dioxide (SiO2)

Basalt (River Rock Cobble)

Extrusive mafic volcanic rock (Basalt)

Sandstone (Ferruginous)

Arenite with Iron-Oxide Cement

Sandstone (Quartzose Sandstone)

Arenite (SiO2 principal component)

Basalt with Quartz/Calcite matrix

Basalt (SiO2 with Ca/Mg/Fe silicates) on a Mineral Matrix

Sandstone

Clastic sedimentary rock (primarily SiO2)

Clear/White Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Quartzite River Rock

Quartzite (SiO2)

Sandstone (Ferruginous)

Arenite (SiO2 with iron oxide impurities)

Basalt

Mafic extrusive igneous rock

Banded Calcite (often sold as 'Travertine' or 'Mexican Onyx')

Calcium Carbonate (CaCO3)

Limestone

Calcium Carbonate (CaCO3)

Pink Feldspar

Orthoclase Feldspar (KAlSi3O8)

Quartz Vein on Matrix

Silicon Dioxide (SiO2)

Limestone

Calcium Carbonate (CaCO3)

Vesicular Basalt

Basalt (principally Plagioclase and Pyroxene)

Sandstone (Quartzose)

Arenite (primarily SiO2)

Schist

Mica Schist (primarily consisting of muscovite KAl2(AlSi3O10)(OH)2 or biotite K(Mg,Fe)3(AlSi3O10)(OH)2)

Sandstone

Arenite (SiO2 based)

Unakite

Epidotized Granite

Basalt (Weathered River Stone)

Basalt (Extrusive Mafic Igneous Rock)

Peridot in Basalt

Olivine ((Mg, Fe)2SiO4) in Basalt

Milky Quartz

Silicon Dioxide (SiO2)

Quartz Geode

Silicon Dioxide (SiO2)

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Wishing Stone (Basalt/Greywacke with Quartz Vein)

Basalt or Siltstone with SiO2 (Quartz) hydrothermal intrusion

Dalmation Jasper (Dalmation Stone)

Perthitic feldspar-quartz-amphibole rock

Basalt River Stone

Basalt (Aphanitic Mafic Igneous Rock)

Basalt River Cobble

Vitreous aphanitic Basalt

Quartz Geode

Silicon Dioxide (SiO2) in Host Rock

Unakite

Epidotized Granite

Ammonite Fossil in Limestone Matrix

Ammonoidea (subclass) in Calcium Carbonate (CaCO3)

Scoria (Lava Rock)

Scoria (extrusive volcanic rock)