Sedimentary (If Natural Jasper) Or Artificial (If Slag)

Quartz Druze on Matrix

Silicon Dioxide (SiO2)

Geode (unopened)

Calcedony-lined Geode (SiO2)

Ferruginous Sandstone (with possible trace fossils)

Arenite with Iron-Oxide Cement (SiO2 with Fe2O3)

Sandstone

Clastic Sedimentary Rock (composed mostly of quartz and/or feldspar)

Chert (White-Grey variety)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Chert (Arrowhead/Tool Grade)

Microcrystalline Quartz (SiO2)

Coarse Sand Grain / Lithic Fragment

Clastic Sediment (Lithic fragment or Quartz/Feldspar grain)

Chert (often called Flint when dark or worked)

Cryptocrystalline silica (SiO2)

Corundum

Corundum (Aluminium oxide, Al2O3)

Bivalve Fossil (Clam/Mollusk)

Class: Bivalvia (Order: Veneroida), Calcium Carbonate (CaCO3)

Red Sandstone

Clastic sedimentary rock (primarily SiO2 with Fe2O3)

Fossil Shark Tooth (embedded in matrix)

Lamniformes (likely Cretalamna or Squalicorax) within phosphatic/calcareous matrix

Sandstone

Arenite (SiO2 with Fe2O3)

Chert (containing a small fossil)

Microcrystalline Quartz (SiO2)

Chert (and Chert Geode)

Silicon Dioxide (SiO2)

River Cobble (Conglomerate context)

Unconsolidated Fluvial Alluvium (comprised of various lithologies like Quartzite, Granite, or Basalt)

Conglomerate

Conglomerate (clastic sedimentary rock)

Chert (Yellow/Tan)

Microcrystalline Quartz (SiO2)

Rose Quartz

Silicon Dioxide (SiO2) with trace impurities of Titanium, Manganese, or Iron

Quartz Vein in Host Rock

Silicon Dioxide (SiO2) within Sedimentary/Metamorphic Matrix

Chert (and Chalcedony/Agate mixture)

Microcrystalline Quartz (SiO2)

Shiva Lingam

Cryptocrystalline Quartz (Jasproid/Sandstone) with Iron Oxide (Fe2O3)

Conglomerate

Conglomerate (Sedimentary Clastic Rock)

Ferruginous Sandstone (with Iron Oxide staining)

Clastic Sedimentary Rock - Quartz Arenite/Wacke

Conglomerate

Conglomerate rock

Banded Calcite (often sold as Onyx Marble)

Calcite (Calcium Carbonate, CaCO3)

Sandstone, Quartzite, and River Pebbles

Silicon Dioxide (SiO2) based Sedimentary/Metamorphic structures

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Gneiss with Quartz Veining

Gneiss (High-grade regional metamorphic rock)

Amethyst and Hematite Bracelet

Amethyst (SiO2) and Hematite (Fe2O3)

Quartz (Druzy Quartz)

Silicon Dioxide (SiO2)

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

Calcium Carbonate (CaCO3)

Limestone

Sedimentary Calcite (CaCO3)

Chert Arrowhead (Projectile Point)

Microcrystalline Quartz (SiO2)

Geodal Limestone / Calcite Druze

Calcium Carbonate (CaCO3)

Pyrite (on Quartz matrix)

Iron Sulfide (FeS2)

Fossilized Gastropod in Chert/Limestone

Internal mold of Gastropoda (Class) with CaCO3 or SiO2 mineral formula

Chert (Nodule)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Azurite-Malachite (often called Azerite Malachite or Azurmalachite)

Azurite (Cu3(CO3)2(OH)2) and Malachite (Cu2CO3(OH)2)

Fossiliferous Limestone (Gritstone/Marl)

CaCO3 (Calcium Carbonate) with Fossil Inclusions

Honeycomb Coral Fossil (Petoskey-type Coral)

Favosites (Extinct Colonial Tabulate Coral), CaCO3

Yellow Calcite

Calcium Carbonate (CaCO3)