Sedimentary Rock

Septarian Nodule (Dragon Stone) sphere

Septarian concretion (Calcite, Aragonite, and Limestone)

Chert (specifically Green Chert/Jasper)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Gneiss

Metamorphic rock of high-grade regional metamorphism

Quartz (likely) / Siliceous rock with quartz phenocrysts (if a rock fragment)

Quartz (SiO₂)

Pumice

Pumice (volcanic rock)

Jasper

Jasper (Silica/Quartz) - SiO2

Gneiss (with Quartz-Feldspar vein)

Gneiss (high-grade metamorphic rock) containing Quartz (SiO2) and Feldspar (KAlSi3O8 – NaAlSi3O8 – CaAl2Si2O8)

Petrified Wood

Silicified Wood (SiO2)

Marble (Carrara style)

Recrystallized Calcite-rich Metamorphic Rock (CaCO3)

Gneiss

High-grade regional metamorphic rock (Foliated)

Banded Gneiss

Gneiss (High-grade regional metamorphic rock)

Sandstone with Tafoni Weathering

Arenite (SiO2 based)

Montana Moss Agate

Chalcedony (SiO2) with Manganese/Iron oxide inclusions

Red Sandstone

Arenite (primarily Quartz with Hematite cement)

Red Sandstone

Arenite (predominantly SiO2 with Fe2O3)

Red Jasper

Silicon Dioxide (SiO2) with Hematite inclusions

Tree Agate

Dendritic Agate (Silicon Dioxide, SiO2)

Green Moss Agate

Silicon Dioxide (SiO2) with inclusions of hornblende or chlorite

Banded Chert (with Quartz Vein)

Microcrystalline Silica (SiO2)

Greywacke (River Pebble)

Greywacke sandstone with quartz veining

Fossiliferous Limestone (Coquina / Shell Limestone)

Bioclastic Limestone (CaCO3)

Quartz Geode

Silicon Dioxide (SiO2) in a Secondary Sedimentary/Volcanic cavity

Quartz Vein in Host Rock

Silicon Dioxide (SiO2) within Sedimentary or Igneous Matrix

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

Quartz (SiO2 - Silicon Dioxide)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Gneiss

High-grade foliated metamorphic rock

Anthracite Coal

Anthracite (Carbon-rich metamorphic rock)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Quartz (with iron oxide staining)

Silicon Dioxide (SiO2)

Basalt with Caliche Crust

Aphanitic Mafic Igneous Rock with Calcium Carbonate (CaCO3) coating

River Cobble (Salt and Pepper Gneiss)

Gneiss (High-grade regional metamorphic rock)

Mica Schist

Mica Schist (KAl2(AlSi3O10)(OH)2 / K(Mg,Fe)3AlSi3O10(OH)2)

Banded Chert (Ironstone/Jasper)

Cryptocrystalline Quartz (SiO2) with Iron Oxides

Tufa

Calcareous Tufa (CaCO3)

Chert (Nodule / Geode fragment)

Microcrystalline Quartz (SiO2)

Banded Chert (Jasper)

Silicon Dioxide (SiO2)

Jasper with Quartz Veining

Silicon Dioxide (SiO2) with impurities

Granitic Gneiss

Gneiss (High-grade regional metamorphic rock)

Agate (specifically, a slice of a Blue Lace or Chalcedony Agate nodule)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Common Opal

Hydrated silica (SiO2 " nH2O)

Agate (Grey Agate Slice)

Microcrystalline Quartz (SiO2)

Agate (specifically Waterline or Onyx-type Agate)

Silicon Dioxide (SiO2) - variety Chalcedony