Sedimentary (With Some Aspects Of Mineral Replacement)

Satin Spar (Selenite)

Gypsum (Calcium Sulfate Dihydrate) - CaSO4·2H2O

Schist

Schist (various mineralogical compositions including mica, chlorite, talc, etc.)

Ironstone Concretion (Moqui Marble Type)

Goethite/Hematite-cemented Sandstone Concretion

Rhodonite

Manganese Silicate (Mn,Fe,Mg,Ca)SiO3

Gneiss

Gneiss (High-grade metamorphic rock)

Chalcedony (Agate)

Cryptocrystalline Quartz (SiO2)

Sandstone (Wonderstone)

Arenite (composed primarily of SiO2 with Fe2O3 impurities)

Pyrite

Iron Sulfide (FeS2)

Gneiss (specifically a water-worn pebble)

Gneiss

Sulfur

Sulfur (S8)

Fossilized Shark Tooth

Carcharodon carcharias (fossilized) / Hydroxyapatite permineralized with silica or iron

Pink Opal

Hydrated Amorphous Silica (SiO2·nH2O)

Gneiss (specifically Granite Gneiss)

Gneiss (High-grade Regional Metamorphic Rock)

Chalcedony (Common Opal or Agate variant)

Silicon Dioxide (SiO₂)

Red Sandstone

Arenite (predominantly SiO2 with Fe2O3)

Almandine Garnet

Almandine (Fe3Al2Si3O12)

Fossil Brachiopod Cast (Atrypa species)

Phylum Brachiopoda, Class Rhynchonellata, Order Atrypida

Chert (Nodular Chert)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert / Flint with Cortex

Silicon Dioxide (SiO2)

Petrified Wood

Silicified wood (Quartz/Chalcedony replacement of organic matter)

Chert (specifically Jasper or Brown Chert node)

Microcrystalline Quartz (SiO2)

Jasper (Iron-stained Chert)

Silicon Dioxide (SiO2) with iron oxide inclusions

Sandstone Concretion

Clastic Sedimentary Concretion (primarily SiO2 with Fe2O3 cement)

Aragonite (variety 'Flos Ferri')

Aragonite (CaCO3)

Echinoid Fossil (Commonly called a Sea Urchin or Heart Urchin)

Phylum Echinodermata, Class Echinoidea

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Red Sandstone

Sandstone (mainly SiO2 with Iron Oxide cement)

Gneiss

Gneissic Metamorphic Rock

Agate Geode

Cryptocrystalline Quartz (SiO2)

Sandstone

Arenite (composed primarily of SiO2)

Chert (and Jasper/Flint variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Banded Gneiss (with Quartz Vein)

Gneiss (Metamorphic rock of varying mineralogy)

Red Jasper

Silicon dioxide (SiO2) with iron oxide (Fe2O3) inclusions

Jasper

Silicon Dioxide (SiO2) with iron oxide impurities

Honeycomb Coral Fossil (Petoskey-type Coral)

Favosites (Extinct Colonial Tabulate Coral), CaCO3

Gneiss (with Quartzite and Mica)

Gneiss

Jasper-Quartz Conglomerate / Chert

Siliceous Sedimentary Rock (SiO2)

Chert (specifically Flint or Novaculite variant)

Chert (Microcrystalline Quartz, SiO2)

Chert (Flint)

Microcrystalline or cryptocrystalline quartz (SiO2)

Chert (Nodule)

Silicon Dioxide (SiO2)

Fossilized Pycnodonte Oyster

Pycnodonte (Gryphaeostrea) species; Composition is Calcium Carbonate (Calcite/Aragonite)

Ironstone Concretion / Goethite Nodules

Ironstone (composed primarily of Goethite FeO(OH) and Limonite)