Limestone

Chert (Field-collected variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Yellow Jasper)

Microcrystalline Quartz (SiO2)

Chert Nodule (Fossiliferous Chert)

Microcrystalline Quartz (SiO2)

Yellow Chert or Jasper

Silicon Dioxide (SiO2)

Flint

Silicon Dioxide (SiO2) - variety of Chert

Green Fluorite

Fluorite (Calcium Fluoride, CaF2)

Pyrite Geode (Sparkling Druzy)

Iron Sulfide (FeS2) in Sedimentary Nodule

Quartz Geode

Silicon Dioxide (SiO2)

Chert (specifically Tan Chert)

Chert (SiO2)

Chert (Pebble)

Chert (Microcrystalline Quartz, SiO2)

Limonite with Galena

FeO(OH)·nH2O (Limonite) and PbS (Galena)

Chert (Yellow Jasper/Flint)

Microcrystalline Quartz (SiO2)

Chert (Black Flint)

Silicon Dioxide (SiO2)

Fluorite (Purple/Blue variety)

Calcium Fluoride (CaF2)

Geode (unopened)

Chert / Chalcedony Geode (SiO2)

Petoskey Stone (Fossilized Coral)

Hexagonaria percarinata

Quartz Geode

Silicon Dioxide (SiO2) within a secondary sedimentary structure

Chert (Jasper/Flint variety)

Microcrystalline Quartz (SiO2)

Charoite

K(Ca,Na)2Si4O10(OH,F)·H2O

Chert (variously known as Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Galena

Lead Sulfide (PbS)

Chert (specifically Flint or Jasper variant)

Silicon Dioxide (SiO2)

Chert (Jasper/Pebble)

Microcrystalline Quartz (SiO2)

Fluorite in Host Rock

Calcium Fluoride (CaF2)

Dyed Magnesite (often sold as Red Turquoise or Howlite)

Magnesium Carbonate (MgCO3)

Lapis Lazuli

Lapis Lazuli (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2

Chert (Jasper)

Microcrystalline Quartz (SiO2)

Orange Calcite

Calcium Carbonate (CaCO3)

Chert (often called Flint for dark variants)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert / Flint Nodule

Silicon Dioxide (SiO2)

Chert (Jasper)

Silicon dioxide (SiO2)

Amphibolite with Hornblende

Amphibole-rich Metamorphic Rock (Ca2(Mg,Fe)5Si8O22(OH)2)

Chert (Lightly weathered variety)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Lapis Lazuli

Sodalite-rich metamorphic rock containing Lazurite (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2

Optical Calcite (Iceland Spar)

Calcite (Calcium Carbonate, CaCO3)

Green Fluorite

Fluorite (Calcium Fluoride, CaF2)

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Apatite

Apatite group mineral (e.g., Fluorapatite - Ca5(PO4)3F, Chlorapatite - Ca5(PO4)3Cl, Hydroxylapatite - Ca5(PO4)3(OH))

Chert (Jasper variety)

Cryptocrystalline quartz (SiO2)

Chert (and its variety Flint)

Silicon dioxide (SiO2) / Microcrystalline quartz

Chert (Flint nodule)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Chert (Nodule)

Microcrystalline Quartz (SiO2)