Limestone

Chert Nodule (Fossiliferous Chert)

Microcrystalline Quartz (SiO2)

Lapis Lazuli

Lazurite-rich metamorphic rock (approx. Na6Ca2(Al6Si6O24)(S,SO4,Cl)1,2)

Yellow Chert or Jasper

Silicon Dioxide (SiO2)

Quartz Geode

Silicon Dioxide (SiO2) within a secondary sedimentary structure

Fluorite (Purple/Blue variety)

Calcium Fluoride (CaF2)

Chert (specifically Tan Chert)

Chert (SiO2)

Green Fluorite

Fluorite (Calcium Fluoride, CaF2)

Pyrite Geode (Sparkling Druzy)

Iron Sulfide (FeS2) in Sedimentary Nodule

Charoite

K(Ca,Na)2Si4O10(OH,F)·H2O

Lapis Lazuli

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

Dyed Magnesite (often sold as Red Turquoise or Howlite)

Magnesium Carbonate (MgCO3)

Chert (often called Flint for dark variants)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Galena

Lead Sulfide (PbS)

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

Amphibolite with Hornblende

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

Travertine

Terrestrial Sedimentary Rock (CaCO3)

Chert / Flint Conglomerate

Silicified Sedimentary Breccia (primarily SiO2)

Quartzite River Pebble

Quartzite (primarily SiO2)

Yellow Calcite

Calcium Carbonate (CaCO3)

Petoskey Stone

Hexagonaria percarinata (Fossilized Rugose Coral)

Chert / Flint

Cryptocrystalline quartz (SiO2)

Orange Calcite (Carved as a Horned Skull)

Calcium Carbonate (CaCO3)

Chert (specifically a stream-worn Chert Nodule)

Sedimentary Cryptocrystalline Quartz (SiO2)

Chert (Yellow Jasper)

Microcrystalline Quartz (SiO2)

Chert (containing small fossils)

Chert (Microcrystalline Quartz, SiO2)

Quartz Geode in Sedimentary Matrix

Silicon Dioxide (SiO2) within a limestone/dolostone host

Chert Pebble/Nodule

Chert (a microcrystalline or cryptocrystalline sedimentary form of quartz, SiO2)

Celestine (or Celestite)

Strontium sulfate (SrSO4)

Chert

Siliceous sedimentary rock (predominantly microcrystalline quartz, SiO2)

Chert (specifically Flint)

Cryptocrystalline Quartz (SiO2)

Chert (Jasper)

Microcrystalline Quartz (SiO2) with Iron Oxide inclusions

Emerald

Beryl (Be3Al2(SiO3)6) with Chromium/Vanadium impurities

Chert (Chalcedony/Agate)

Microcrystalline Quartz (SiO2)

Chert (Jasper variation)

Microcrystalline Quartz (SiO2)

Chert (Jasper/Quartzite variety)

Microcrystalline Silica (SiO2)

Chert Pebble

Microcrystalline Quartz (SiO2)

Green Fluorite

Calcium Fluoride (CaF2)