Sedimentary (Silica Rich Mineral Variety)

Chert (Jasper-like Silicate)

Microcrystalline quartz (SiO2)

Obsidian

Volcanic Glass (predominantly SiO2)

Moonstone

Adularia (orthoclase feldspar variety)

Green Aventurine

Aventurine (a variety of Quartz, SiO2 with fuchsite inclusions)

Chert (Jasper variation)

Microcrystalline Quartz (SiO2)

Quartz Druzy on Matrix (likely Agate or Jasper)

Silicon Dioxide (SiO2) with various mineral inclusions

Travertine (Tufa)

Calcium Carbonate (CaCO3)

Druzy Quartz on Milky Quartz

Silicon Dioxide (SiO2)

Chert (Jasper)

Microcrystalline Quartz (SiO2) with Iron Oxide impurities

Milky Quartz Pebbles

Silicon Dioxide (SiO2)

Quartz (Amethyst variety)

Silicon Dioxide (SiO2)

Botryoidal Chalcedony (Desert Rose / Agate)

Silicon Dioxide (SiO₂)

Pink Tourmaline in Quartz Matrix

Elbaite (Na(Li,Al)3Al6(BO3)3Si6O18(OH)4) with Quartz (SiO2)

Jasper (specifically Polychrome or Desert Jasper)

Silicon Dioxide with impurities (SiO2)

Chert (specifically Flint)

Microcrystalline Quartz (SiO2)

Olivine (Peridot)

Magnesium Iron Silicate (Mg,Fe)2SiO4

Iolite (Cordierite)

Cordierite (Magnesium Aluminum Silicate), Mg2Al4Si5O18

Milky Quartz

Silicon Dioxide (SiO2)

Sandstone (with Liesegang rings or Oxidation)

Arenite (primarily Quartz SiO2 with Iron Oxide Fe2O3 staining)

Blue Sapphire

Corundum (Al2O3)

Chert / Flint Conglomerate

Silicified Sedimentary Breccia (primarily SiO2)

Sandstone (Red/Brown Variety)

Arenite (SiO2 with iron oxide impurities)

Moss Agate

Chalcedony (SiO2) with inclusions of hornblende or chlorite

Limonite (Iron Ore)

Limonite (FeO(OH)·nH2O)

Amethyst

Amethyst (Silicon Dioxide, SiO2)

Chert (Common Opal/Chalcedony mixture)

Silicon Dioxide (SiO2)

Blue Quartzite (Dyed)

Silicon Dioxide (SiO2) with inclusions

Agate (translucent pebble)

Silicon dioxide (SiO2) - Microcrystalline Quartz

Schorl (Black Tourmaline) in Matrix

Sodium Iron Aluminum Borosilicate Hydroxide (NaFe2+3Al6Si6O18(BO3)3(OH)3OH)

Chert (Yellow Jasper)

Microcrystalline Quartz (SiO2)

Chert (often called Flint when dark)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Sandstone Chert/Quartzite

Silicon Dioxide (SiO2) - Sedimentary Sandstone / Orthoquartzite

Carnelian

Chalcedony (Silicon Dioxide, SiO2 with Iron Oxide impurities)

Dendritic Agate (specifically Orange/Tumbled)

Silicon Dioxide (SiO2) with Oxide Inclusions

Amethyst Geode

Silicon Dioxide with trace inclusions of Iron (SiO2)

Yellow Quartz (Citrine Quartz or Yellow Chalcedony)

Silicon Dioxide (SiO2)

Chalcedony (specifically Agate or Water-worn Quartzite)

Silicon Dioxide (SiO2)

Carnelian

SiO2 (Silicon Dioxide) - Translucent Chalcedony

Calcite

Calcite (CaCO₃)

Green Jasper (Chert)

Silicon Dioxide (SiO2)

Hematite

Ferric oxide (Fe2O3)

Chert (Jasper-rich)

Microcrystalline/Cryptocrystalline Quartz (SiO2)