Limestone

Basalt Pebble

Basalt

Quartzite Pebbler

Quartzite (primarily SiO2)

Druzy Quartz Geode (Oco or Moroccan variety)

Silicon Dioxide (SiO2)

Druzy Quartz (part of a Geode)

Silicon Dioxide (SiO2)

Stromatolite

Biogenic Sedimentary Rock (Lithified microbial mat)

Chert (Iron-stained)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Chert (Grey-Green Var.)

Silicon Dioxide (SiO2)

Rhyolite

Rhyolite (Extrusive Igneous Rock)

Chert (Quartz Variety)

Chert (Silicon Dioxide, SiO2)

Herkimer Diamond in Matrix

Quartz (SiO2) in Dolostone (CaMg(CO3)2)

Nephrite Jade

Nephrite (Ca2(Mg, Fe)5Si8O22(OH)2)

Green Chert (Jasper)

Silicon Dioxide (SiO2)

Echinoid Fossil (Sea Urchin)

Echinoidea (specifically likely Schizaster or similar genus), calcium carbonate (CaCO3)

Chert (often called Flint when dark)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Pink Chert (Brecciated Jasmine/Jasper)

Silicon Dioxide (SiO2)

Honeycomb Coral Fossil

Favosites (extinct genus of tabulate coral)

Chert (variant Flint)

Silicon Dioxide (SiO2)

Chert (Nodule)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Optical Calcite (Iceland Spar)

Calcium Carbonate (CaCO3)

Basalt

Basalt (principally Plagioclase and Pyroxene)

Wonderstone (Liesegang Sandstone)

Silicified Sandstone with Liesegang Rings (SiO2 + FeO(OH))

Chert / Flint (with Iron Staining)

Silicon Dioxide (SiO2)

Chalcedony (Agate/Carnelian)

Cryptocrystalline Silicon Dioxide (SiO2)

Quartz Geode

Silicon Dioxide (SiO2) in a concretionary structure

Red Granite

Phaneritic Plutonic Rock (High Potassium Feldspar)

Ammonite Fossil (Polished Section)

Ammonoidea (typically mineralized with Calcite CaCO3)

Banded Chert

Cryptocrystalline Quartz (SiO2)

Nephrite Jade

Nephrite

Corundum (Ruby/Sapphire crystal)

Al2O3 (Aluminum Oxide)

Nephrite Jade

Nephrite (Ca2(Mg, Fe)5Si8O22(OH)2)

Celestine (or Celestite)

Celestine (Strontium Sulfate, SrSO4)

Nephrite Jade (River Bed Pebble)

Nephrite (Ca2(Mg, Fe)5Si8O22(OH)2)

Nephrite Jade

Tremolite-Actinolite solid solution Ca2(Mg,Fe)5Si8O22(OH)2

Fossiliferous Limestone with Crinoid stems

Calcite-rich Biogenic Sedimentary Rock (CaCO3)

Chert (Jasper variety) with Iron Oxide staining

Cryptocrystalline Quartz (SiO2) with Goethite/Limonite impurities

Emerald

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

Banded Flint / Chert

Silicon Dioxide (SiO2)

Fluorite Tower

Fluorite (Calcium Fluoride - CaF2)

Emerald in Matrix

Emerald (Beryllium Aluminum Silicate), Be3Al2(SiO3)6

Agatized Chert / Chalcedony

Silicon Dioxide (SiO2)

Lapis Lazuli

Lapis lazuli (a metamorphic rock primarily composed of Lazurite, (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2)

Chert (Yellow Jasper/Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)