Limestone

Quartzite

Quartzite (SiO2)

River Quartzite (Water-worn Quartzite)

Quartzite (primarily SiO2)

Marble

Marble (metamorphosed limestone/dolostone). Predominantly composed of Calcite (CaCO3) for marble derived from limestone, or Dolomite (CaMg(CO3)2) for marble derived from dolostone.

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Fluorite (Rainbow Fluorite)

Fluorite (Calcium Fluoride, CaF2)

Travertine (often colloquially called Tufa)

Chemical Sedimentary Calcium Carbonate (CaCO3)

Chert (specifically Iron-stained River Cobble)

Silicon Dioxide (SiO2)

Green Banded Chert (Agate/Jasper)

Silicon Dioxide (SiO2) with trace impurities of Chlorite or Glauconite

Chert (Yellow/Tan Variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Jasper (Red Jasper)

Silicon Dioxide (SiO₂)

River Quartzite Siltstone

Quartz-rich Meta-siltstone (SiO2 dominated)

Banded Chert (or Banded Jasper)

Silicon Dioxide (SiO2) with Iron Oxide impurities (Hematite/Goethite)

Red Shale

Lutite (primarily composed of clay minerals and iron oxides like hematite, Fe2O3)

Chert (Nodule)

Cryptocrystalline Silica (SiO2)

Chert (Nodule)

Microcrystalline Quartz (SiO2)

Banded Calcite (often commercially called 'Mexican Onyx')

Calcium Carbonate (CaCO3)

Chert (Iron-Stained)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Druzy Quartz on Host Rock

Silicon Dioxide (SiO2)

Favosites (Honeycomb Coral Fossil)

Favosites sp. (Phylum Cnidaria, Order Tabulata)

Quartz Geode

Silicon Dioxide (SiO₂)

Limonite and Goethite encrusted Chert/Ironstone

Hydrated Iron Oxide (FeO(OH)·nH2O) with cryptocrystalline Silica (SiO2)

Turquoise

Hydrated phosphate of copper and aluminium [CuAl6(PO4)4(OH)8·4H2O]

Malachite

Malachite (Cu2CO3(OH)2)

Chert (also known as Flint or Common Chalcedony)

Cryptocrystalline Silica (SiO2)

Dendritic Agate or Manganese Nodule in Chert/Limestone

Silicon Dioxide (SiO2) with Manganese Oxide (MnO2) inclusions

Moss Agate

Silicon Dioxide (SiO2) with inclusions of Manganese or Iron oxide

Chert (Brown variety / Common Jasper)

Microcrystalline Quartz (SiO2)

Lapis Lazuli

Lazurite (primary mineral component), (Na,Ca)8(AlSiO4)6(S,SO4,Cl)1-2

Chert (variously identified as Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Banded Calcite (often sold as 'Mexican Onyx' or 'Green Onyx')

Calcite (CaCO3)

Chert (Iron-stained)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Sodalite

Na8(Al6Si6O24)Cl2

Raw Emerald

Beryl (Be3Al2(SiO3)6) with Cr/V impurities

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Chalcedony

Silicon dioxide (SiO2) - Microcrystalline quartz

Celestite (Celestine)

Strontium sulfate (SrSO4)

Fluorite

Calcium Fluoride (CaF2)

Dragon Stone (Septarian Nodule/Concretion)

Septarian Concretion (Composition: Calcite, Aragonite, Limestone/Clay)

Septarian Nodule (or Mudstone with Septarian Cracking)

Septarian Concretion (Composition: Calcite, Aragonite, and Limestone/Claystone)

Septarian Nodule

Septarian Concretion (Complex of Calcite, Aragonite, and Limestone/Mudstone)

Fluorite (Durango Fluorite)

Calcium Fluoride (CaF2)

Flint (variety of Chert)

Silicon Dioxide (SiO2)