Sedimentary Rock (Specifically A Concretion Or Possibly A Geode)

Jasper (Yellow Jasper)

Silicon Dioxide (SiO2) with iron inclusions

Basalt

Basalt (Mafic volcanic rock)

Amethyst Geode

Silicon Dioxide with trace inclusions of Iron (SiO2)

Ironstone Concretion (Limonite/Goethite)

Ferruginous Siltstone / Limonite Concretion (FeOO(OH)·nH2O)

Quartz (likely Rose Quartz or Milky Quartz based on color)

Quartz (SiO2 - Silicon Dioxide)

Druzy Quartz Geode (Vug)

Silicon Dioxide (SiO2)

Fossil shark tooth

Likely fossilized shark tooth, possibly Carcharhinus or Otodus species

Agate

Silicon dioxide (Chalcedony), SiO2

Quartz Druzy (Geode Fragment)

Silicon Dioxide (SiO2)

Chert (Flint)

Microcrystalline quartz (SiO2)

Pink Amethyst (or Pink Quartz)

Silicon Dioxide (SiO2) with trace inclusions

Amethyst and Smoky Quartz (Tumbled)

Silicon Dioxide (SiO2) with trace impurities iron (Amethyst) and aluminum/radiation (Smoky Quartz)

Chert (Jasper)

Microcrystalline Quartz (SiO2) with iron oxide impurities

Druzy Quartz on Matrix

Silicon Dioxide (SiO2)

Quartz Geode Segment

Crystalline Silicon Dioxide (SiO2)

Weathered iron-rich concretion or ironstone nodule

Goethite–hematite limonite concretion (FeO(OH), Fe₂O₃, and hydrated iron oxides)

Amethyst on Matrix

Amethyst (Silicon Dioxide, SiO2) with impurities of iron and irradiation

Druzy Quartz

Silicon Dioxide (SiO2)

Sandstone (Ferruginous)

Clastic sedimentary rock (SiO2 with Fe2O3)

Diabase

Diabase (also known as Dolerite)

Quartz

Silicon Dioxide (SiO2)

Sandstone (Quartz Arenite)

Sandstone (SiO2 with possible mineral cements)

Chert (Yellow Jasper)

Microcrystalline Quartz (SiO2)

Chert

Chert (SiO2)

Quartz Geode (Cracked Open Fragment)

Silicon Dioxide (SiO2)

Sandstone

Arenite (specifically Quartz Arenite)

Sandstone (with Possible Iron Staining/Crust)

Arenite (SiO2 based)

Railway Ballast (Crushed Traprock / Basalt with Iron Oxide Staining)

Mafic Volcanic Rock (Basalt / Diabase with Fe2O3.nH2O limonite coatings)

Druzy Quartz on Sandstone

Silicon Dioxide (SiO2) on Sedimentary Host Rock

Weathered sandstone or fine-grained sedimentary rock

Quartz-rich sandstone, possibly arkose or lithic sandstone

Basalt (Vesicular)

Extrusive mafic igneous rock; primarily (Ca, Na)(Mg, Fe, Al)(Si, Al)2O6 with (Ca, Na)(Al, Si)4O8

Jasper (specifically Bloodstone/Heliotrope or Dark Green Jasper)

Cryptocrystalline Quartz (SiO2) with inclusions

Quartz Druze

Silicon Dioxide (SiO2)

Weathered iron-rich rock, possibly garnet schist or mica schist

Foliated metamorphic rock; likely mica schist with iron oxides and quartz, but exact identification is uncertain from the image

Jasper with Iron Staining

Silicon Dioxide (SiO2) with Hematite impurities

Drupa or Druzy Quartz on Geode Fragment

Crystalline Silicon Dioxide (SiO2)

Iron-Oxide Concretion (Moqui Marble)

Goethite/Hematite Concretion (Fe2O3 / FeO(OH))

Druzy Quartz on Matrix

Silicon Dioxide (SiO2) on host rock

Druzy Quartz on Chalcedony Matrix

Silicon Dioxide (SiO2)

Geode (Unopened)

Silica-lined Vug (primarily SiO2)

Quartz Geode (with Agate banding)

Silicon Dioxide (SiO2)

Biotite granite (weathered granitic rock)

Granite; chiefly quartz (SiO₂), feldspar, and biotite mica