Sedimentary (With Some Aspects Of Mineral Replacement)

Chalcedony (Common Opal/Chert variety)

Silicon Dioxide (SiO2)

Schorl (Black Tourmaline) in Quartz and Feldspar

NaFe2+3Al6(Si6O18)(BO3)3(OH)3(OH)

Tiger's Eye

SiO2 (Silicon Dioxide with inclusions of Goethite/Limonite)

Ferruginous Sandstone

Clastic sedimentary rock (SiO2 with Fe2O3/FeO(OH) cement)

Ferruginous Quartz on Ironstone

Silicon Dioxide (SiO2) with Hematite (Fe2O3)

Kambaba Jasper

Stromatolite (Fossilized Algae)

Gneiss (River Cobble)

Gneiss (Foliated Metamorphic Rock)

Fluorite

Fluorite (Calcium Fluoride, CaF2)

Biotite Mica

Biotite (K(Mg,Fe)3AlSi3O10(F,OH)2)

Shale

Shale (clastic sedimentary rock)

Ferruginous Sandstone

Clastic sedimentary rock (primarily Quartz with Iron Oxide cement)

Flexicalymene Trilobite Fossil

Flexicalymene meeki (Order Phacopida, Family Calymenidae)

Chert (often referred to as 'Jasper' when red)

Chert (microcrystalline quartz, SiO₂)

Tiger's Eye

Tiger's Eye (Pseudomorph of Quartz after Crocidolite), SiO2

Fluorite in Matrix

Fluorite (CaF2) within a host rock matrix

Quartz (likely a weathered/tumbled piece)

Quartz (SiO₂)

Specular Hematite and Magnetite Ore

Iron Oxide (Fe2O3 and Fe3O4)

Herkimer Diamond

Quartz (Silicon Dioxide) - SiO2

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2 with iron inclusions)

Granite Gneiss

Gneiss (High-grade regional metamorphic rock)

Ferruginous Sandstone (with Iron Oxide staining)

Clastic Sedimentary Rock - Quartz Arenite/Wacke

Banded Gneiss

Gneiss (High-grade regional metamorphic rock)

Ferruginous Sandstone (Grit)

Clastic Sedimentary (Ironstone-rich Sandstone)

Petoskey Stone

Hexagonaria percarinata (Fossilized Rugose Coral)

Magnetite

Magnetite (Fe3O4)

Petrified Wood

Silicified Wood (SiO2)

Ammonite Fossil in Limestone Matrix

Ammonoidea (subclass) in Calcium Carbonate (CaCO3)

Chert / Flint (with Crinoid Stem Molds)

Microcrystalline Quartz (SiO2)

Gneiss (specifically Pink Gneiss)

Gneiss (high-grade regional metamorphic rock)

Gneiss

Gneissic Metamorphic Rock

Kambaba Jasper

Stromatolite (Fossilized Algae)

Fossilized Shark Tooth (Cretaceous to Neogene)

Elasmobranchii dental fossil (likely Squalicorax or similar species)

Travertine (Tufa)

Chemical Sedimentary Limestone (CaCO3)

Chert (often called Flint)

Chert (Microcrystalline Silicon Dioxide, SiO2)

Galena

Lead(II) sulfide (PbS)

Chert (Nodule / Geode fragment)

Microcrystalline Quartz (SiO2)

Jasper (Red Jasper)

Silicon Dioxide (SiO₂)

Chert (often called Flint)

Chert (Cryptocrystalline Quartz, SiO2)

Prehnite

Prehnite (Ca2Al(AlSi3O10)(OH)2)

Limonite

Hydrous Iron Oxide (often Goethite FeO(OH), Lepidocrocite γ-FeO(OH), and other amorphous iron oxyhydroxides)

Banded Chert

Chert (a microcrystalline variety of quartz, SiO2 with minor impurities)

Kambaba Jasper

Stromatolite (Fossilized Algae)