Limestone

River Pebbles (Stream-rounded rocks)

Fluvial Detritus (varied mineralogy)

Petoskey Stone

Hexagonaria percarinata (Fossilized Rugose Coral)

Ferruginous Slag (Iron Smelting Byproduct)

Fused Silicate Scoria (Amorphous mixture of FeO, SiO2, and CaO)

Chert (Jasper/Flint variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Marble (Carrara style)

Recrystallized Calcite-rich Metamorphic Rock (CaCO3)

Chert (specifically Tan/Yellow Chert)

Silicon Dioxide (SiO2)

Chert (Common Opal/Agate inclusion)

Microcrystalline Quartz (SiO2)

Chert (and/or Flint)

Chert (Cryptocrystalline variety of Quartz, SiO2)

Travertine

Travertine (CaCO3 - Calcium Carbonate)

Lapis Lazuli

Lapis lazuli (primary component: Lazurite (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2)

Lapis Lazuli

Na8[Al6Si6O24]n(S,Cl,SO4,OH)2 (Lazurite component)

Lapis Lazuli

Complex mixture of minerals (lazurite, calcite, pyrite, and sodalite); (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2

Septarian Nodule

Septarian Concretion (CaCO3 + CaMg(CO3)2)

Banded Chert

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Chert (Iron-stained)

Chert (Cryptocrystalline Silica, SiO2)

Epidote with Quartz and Feldspar

Ca2(Al2,Fe3+)(SiO4)3(OH) (Epidote complex)

Lapis Lazuli

Lapis Lazuli (A metamorphic rock primarily composed of Lazurite: (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2, along with Calcite and Pyrite)

Chert / Jasper / Agate (Chalcedony Group)

Microcrystalline Quartz (SiO2)

Chert (Red/Brown Variety)

Microcrystalline quartz (SiO2)

Lapis Lazuli

Lapis Lazuli (Rock composed primarily of Lazurite (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2, Calcite, and Pyrite)

Limonite Pseudomorph after Pyrite

Goethite/Limonite FeO(OH)·nH2O replacing Pyrite FeS2

Chert / Flint Nodule

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Banded Chert / Flint

Silicon dioxide (SiO2)

Granite

Phaneritic Igneous Rock (composed primarily of Quartz, Feldspar, and Mica)

Sandstone (Ferruginous)

Ferruginous Sandstone (SiO2 with iron oxide cement)

Chert (specifically a nodule with Chalcendony/Agate banding)

Microcrystalline Quartz (SiO2)

Chert (and Jasper/Flint variant)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Nodule)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (White-Grey variety)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Chert (Quartz Variety)

Chert (mostly SiO2 / Silicon Dioxide)

Chert (and Flint)

Silicon Dioxide (SiO2)

Chert (Green variety)

Microcrystalline Opaline/Quartz (SiO2)

Blue Calcite

Calcium Carbonate (CaCO3)

Ammonite Fossil

Ammonoidea (typically preserved as Calcite CaCO3 or Pyrite FeS2)

Chert (Brown Variety)

Silicon dioxide (SiO2)

Chert (Iron-stained)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Quartz / Quartzite

Silicon Dioxide (SiO2)

Quartz Druze on Matrix (Geode Fragment)

Quartz (Silicon Dioxide, SiO2)

Chert (often called Flint)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Quartz Druse (on Chalcedony/Agate base)

Silicon Dioxide (SiO2)

Chert (specifically Flint)

Chert (Microcrystalline or Cryptocrystalline Quartz, SiO2)

Chert (varieties: Flint or Chalcedony)

Microcrystalline Quartz (SiO2)