Organic Gemstone (Often Associated With Sedimentary Sequences)

Water and Silt (Sedimentary Environment)

Suspended Sediment / H2O (dihydrogen monoxide)

Chert (Brown variety)

Silicon Dioxide (SiO2)

Chert (or Flint)

SiO2 (predominantly microcrystalline quartz)

Chert (White Chert / Flint)

Microcrystalline or Cryptocrystalline Silicon Dioxide (SiO2)

Shale

Fissile Clay-dominant Mudrock (SiO2, Al2O3, K2O, Na2O, CaO, MgO)

Chert (and its variety Flint)

Silicon Dioxide (SiO2) - Microcrystalline or cryptocrystalline Quartz

Banded Chert

Microcrystalline Quartz (SiO2)

Chert (and/or Flint)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Chert (Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert with Quartz Veining

Silicon Dioxide (SiO2)

Tektite

Tektite (Amorphous silica rich glass)

Chert (Jasper/Flint variety)

Microcrystalline quartz (SiO2)

Yellow Jasper

Chalcedony (SiO2) with iron oxide inclusions

Banded Metamorphic Rock (likely Quartzite or Serpentinite/Soapstone)

Metamorphic Rock (possibly a banded Quartzite or a foliated Serpentinite/Talc Schist based on appearance, general term for such a rock is 'Banded Metamorphic Rock' or 'Gneiss' if pronounced banding of different minerals)

Yellow Chert

Sedimentary cryptocrystalline quartz (SiO2)

Chert (Green variety)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Chert (specifically Gray/Blue Chert)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Ironstone Concretion (Ironstone Gourd)

Limonite/Goethite Concretion (FeOO(H))

Turquoise

Turquoise (CuAl6(PO4)4(OH)8·4H2O)

Unakite

Epidotized Granite

Fossilized Wood (with Coal and Limonite)

Petrified Wood (Silicified or Carbonized Flora)

Chert (often called Flint or Jasper locally)

Chert (Microcrystalline Quartz, Formula: SiO2)

African Turquoise (Jasper)

Polychrome African Jasper (often marketed as 'African Turquoise' due to its color, but it is not true turquoise)

Fossiliferous Brachiopod in Shale

Brachiopoda (Phylum) preserved in Carbonaceous Shale

Chert (Iron-stained)

Microcrystalline Quartz (SiO2)

Lepidolite

K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2

Silver (Jewelry Specimen)

Native Silver (Chemical Formula: Ag)

Ironstone Concretion (Limonite/Hematite Nodules)

Ironstone (principally Limonite FeO(OH)·nH2O or Hematite Fe2O3 mixed with silica/clay)

Black Mountain Stone (Seiryu Stone)

Limestone with Calcite veins (CaCO3)

Chert (Iron-stained)

Chert (Silicon Dioxide, SiO2)

Chert (Flint)

Chert (microcrystalline quartz)

Chert (Chert Pebble)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Banded Chert with Quartz Veining

Microcrystalline Quartz (SiO2)

Stromatolite (Fossiliferous Limestone)

Biogenic Limestone (Calcium Carbonate, CaCO3)

Chert (Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Flint)

Chert (Silicon Dioxide, SiO2)

Chert (Nodule)

Silicon Dioxide (SiO2)

Chert (Chert / Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Chert (Jasper/Agate variety)

Microcrystalline Quartz (SiO2)

Epidote

Epidote (Ca2(Al,Fe)3(SiO4)3(OH))

Wonderstone (Liesegang Sandstone)

Silicified Sandstone with Liesegang Rings (SiO2 + FeO(OH))