Sedimentary (Chemically Precipitated Mineral)

Green Onyx (Banded Calcite)

Banded Calcite / Aragonite (CaCO3)

Botryoidal Aragonite (Cave Popcorn)

Aragonite (Calcium Carbonate, CaCO3)

Banded Iron Formation (BIF)

Banded Iron Formation

Dyed Agate Geode Slice

Silicon Dioxide (SiO2) - Banded Chalcedony

Pink Tumbled Agate (Dyed)

Silicon Dioxide (SiO2) with artificial dyes

Pyrite (Limonite Pseudo-morph after Pyrite)

Iron sulfide (FeS2) transitioning to Iron oxide-hydroxide (FeO(OH)·nH2O)

Dyed Chalcedony (Agate)

Silicon Dioxide (SiO2) with artificial pigment

Dyed Blue Agate

Silicon Dioxide (SiO2) with artificial pigment

Orange Calcite

Calcium Carbonate (CaCO3)

Massive Quartz with Host Rock

Silicon Dioxide (SiO2)

Quartz Crystal

Quartz (SiO₂)

Chert (often referred to as Flint)

Chert (Microcrystalline Quartz, SiO2)

Chert (Chert / Flint)

Silicon Dioxide (SiO2)

Limonite (Yellow Ochre)

Hydrated iron(III) oxide-hydroxides (FeO(OH)·nH2O)

Chert (White Chert / Flint)

Microcrystalline or Cryptocrystalline Silicon Dioxide (SiO2)

Quartz Vein in Host Rock

Silicon dioxide (SiO2) veins in metamorphic/igneous host rock

Concrete Fragment

Hardened Portland cement and mineral aggregate

Limonite pseudomorph after pyrite

Goethite / Limonite pseudomorph after Pyrite (Fe3+O(OH) replacing FeS2)

Quartz Pebble

Silicon Dioxide (SiO2)

Chalcedony (Agate Pebble)

Silicon Dioxide (SiO2)

Halite (Rock Salt)

Halite (Sodium Chloride, NaCl)

Quartz Pebble

Silicon Dioxide (SiO2)

Quartz Vein / Quartzite

Silicon Dioxide (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Chert (Common Opal or Flint variant)

Microcrystalline Quartz (SiO2)

Red Chert (Jasper)

Silicon Dioxide (SiO2)

Jasper

Microcrystalline Quartz (SiO2)

Sandstone Pebble with Iron Staining

Clastic Sedimentary Rock (primarily Quartz with Fe2O3 oxides)

Coal (Anthracite or Bituminous)

Carbon (C) with varying hydrocarbon and mineral impurities

Jasper

Chalcedony (cryptocrystalline quartz), SiO2

Wonderstone (Sandstone)

Silicified Quartz Sandstone with Iron Oxide staining

Chalcedony (Agate/Jasper mix in host rock)

Chalcedony (cryptocrystalline Silicon Dioxide, SiO2)

Gold in Quartz Matrix

Native Gold (Au) with Quartz (SiO2)

Chert (specifically Zebra Chert/Flint)

Silicon Dioxide (SiO2)

Chert (Iron-stained)

Microcrystalline silica (SiO2) with trace Iron oxide (Fe2O3)

Fluorite

Calcium fluoride (CaF2)

Snowflake Obsidian

Vitreous Volcanic Glass (Siliceous Obsidian with Cristobalite inclusions)

Gossan (with Limonite and Hematite)

Goethite (FeO(OH)), Limonite (FeO(OH)·nH2O), and Hematite (Fe2O3)

Chert (specifically Gray/Black Chert)

Chert (Microcrystalline or Cryptocrystalline Quartz, SiO2)

Green Quartzite (with possible Epidote/Chlorite inclusions)

Quartzite (primarily SiO2)

Quartz Pebble (on Granite)

Silicon Dioxide (SiO2)

Agate Geode

Silicon Dioxide (SiO2) - Microcrystalline Quartz