None

Chert

Microcrystalline Quartz (SiO2)

Sand and Gravel (Quartz-rich)

Unconsolidated fluvial/beach sediment (primarily Silica/SiO2)

Red Chert (Jasper)

Silicon Dioxide (SiO2)

Banded Sandstone (River Pebble)

Arenite (SiO2 primarily)

Sandstone and Quartzite Specimens

SiO2 with varying mineral/clastic inclusions

Chert

Microcrystalline Quartz (SiO2)

Gold Nugget

Native Gold (Au)

Sandstone with Iron Banding

Arenite with Hematite or Limonite staining (SiO2 with Fe2O3)

Natural Gold Nugget

Native Gold (Au)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Chert

Chert (Microcrystalline Quartz)

Kidney Stone

Calcium Oxalate (CaC2O4), Uric Acid, or Struvite

Jasper

Silicon dioxide (SiO2)

White Howlite

Howlite (Calcium borosilicate hydroxide, Ca2B5SiO9(OH)5)

Chalky Limestone

Carbonate sedimentary rock (CaCO3)

Aura Quartz (Rainbow Quartz)

Silicon Dioxide (SiO2) with metallic vapor coatings

Milky Quartz with Nephrite Jade

Silicon Dioxide (SiO2) with Ca2(Mg,Fe)5Si8O22(OH)2

Fossiliferous Chert (Chert with Crinoid Stem Impression)

Chert (SiO2) with fossil Anthozoan or Crinoid columnals

Chalcedony (specifically Agate or Carnelian)

Silicon Dioxide (SiO2)

Citrine

Silicon Dioxide (SiO2)

Fossilized Shark Tooth

Otodus sp. (approximate genus) / Hydroxyapatite fossil

Dyed Quartz Geode

Silicon Dioxide (SiO2) with artificial pigment

Druzy Quartz on Sandstone

Silicon Dioxide (SiO2) with Quartz crystals

Fossil Shark Tooth

Carcharodon sp. (likely Otodus or similar Lamniformes order)

Sapphire (Blue)

Corundum (Al2O3)

Chondrite Meteorite

Ordinary Chondrite (S-type asteroid origin)

Quartzite with Epidote

Meta-quartzite containing Epidote (Ca2(Al2,Fe)(SiO4)(Si2O7)O(OH))

River Siltstone / Mudstone Pebble

Siltstone (composed of mixed silicate and carbonate minerals)

Yellow Quartzite Pebble

Quartzite (primarily SiO2)

Thunderegg (Agate-filled Geode Node)

Silicon dioxide (SiO2) with various inclusions

Magnetite (Lodestone)

Magnetite (Fe3O4)

Quartzite

Quartzite (SiO2)

Granite

Phaneritic intrusive igneous rock (Granite)

Corundum (variety Ruby/Sapphire)

Aluminum Oxide (Al2O3)

Obsidian

Volcanic glass (SiO2-rich extrusive igneous rock)

Amethyst

Quartz variety; SiO2 (Silicon Dioxide)

Sapphire

Corundum (Al2O3)

Pink Quartzite

Quartzite (SiO2) with trace Iron Oxides

Red Quartzite Pebble

Quartzite (SiO2)

Quartzite Cobble

Quartzite (SiO2)

Black Obsidian

Volcanic Glass (SiO2 with impurities)

Quartzite Pebble

Quartzite (SiO2)