Man Made Byproduct (Often Mistaken For Obsidian Or Emerald)

Aquamarine

Beryl (Be₃Al₂Si₆O₁₈), specifically a blue or cyan variety

Quartz (Iron-Stained Quartz Pebble)

Silicon Dioxide (SiO2)

Ironstone Concretion (Iron-rich Mudstone)

Siderite / Geothite concretion (FeCO3 / FeO(OH))

Chalk

Calcium Carbonate (CaCO3)

Ironstone Concretion (Ironstone Gourd)

Limonite/Goethite Concretion (FeOO(H))

Chert (and Flint)

Silicon Dioxide (SiO2)

Obsidian (Apache Tear)

Obsidian / Amorphous Volcanic Glass (main component: SiO2)

Ironstone Concretion / Limonite-stained Siltstone

Ironstone (primarily Limonite FeO(OH)·nH2O and Siltstone)

Chert (Nodule)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Rainbow Hematite (Man-made/Treated)

Tumbled Hematite with Titanium/Anodized coating (Iron(III) oxide, Fe2O3)

Pumice

Vesicular Rhyolite or Dacite

Jasper

Silicon Dioxide (SiO2)

Chert (Arrowhead Fragment)

Microcrystalline Quartz (SiO2)

Bog Iron / Limonite Concretion

Goethite/Limonite mixture (FeO(OH)·nH2O)

Pyrite in Matrix (Commonly called Fool's Gold)

Iron Sulfide (FeS2)

Liesegang Banded Sandstone (Wonderstone)

Ferruginous Sandstone with Liesegang Rings

Pyrite

Iron Disulfide (FeS2)

Gold

Native Gold (Au)

Chert (specifically Black Chert or Flint)

Cryptocrystalline Quartz (SiO2)

Aragonite (specifically Mexican Marbled Onyx)

Aragonite (Calcium Carbonate, CaCO3)

Diorite

Diorite (Intermediate intrusive igneous rock)

Aquamarine

Aquamarine (Beryl variety); Be3Al2Si6O18

Chert (specifically Flint or Common Chert node)

Silicon Dioxide (SiO2)

Boxwork Siderite or Sepatarian Nodule Weathering

Siderite (FeCO3) with secondary mineralization or Boxwork Geode fragment

Chert (Grey-Green Flint)

Microcrystalline silicon dioxide (SiO2)

Red Chert (Jasper)

Cryptocrystalline Quartz (SiO2) with iron oxide inclusions

Quartzite

Quartzite (SiO2-dominant rock)

Blue Quartzite (Blue Aventurine / Dumortierite Quartz)

Quartzite with inclusions (SiO2 with AlAl4BSi3O18)

Amazonite

Amazonite (KAlSi3O8); a green variety of Microcline feldspar

Obsidian / Chert (Arrowhead Artifact)

Obsidian (volcanic glass, SiO2 with impurities)

Quartz Pebble (Sea Glass-like Quartz)

Quartz (Silicon Dioxide - SiO2)

Amethyst (Quartz)

SiO2 (Silicon Dioxide)

Sodalite

Na8(Al6Si6O24)Cl2 (Sodium Aluminum Silicate Chloride)

Ironstone Concretion / Limonite Node

Limonite (Hydrated Iron Oxide, FeO(OH)·nH2O) with Goethite/Hematite

Blue Quartz (Aventurine)

Silicon Dioxide (SiO2) with fibrous inclusions (commonly Dumortierite)

Dalmation Stone (Dalmation Jasper)

Peralkaline rock (primarily Feldspar and Quartz with Arfvedsonite spots)

Green Aventurine

Silicon Dioxide (SiO2) with Fuchsite inclusions

Green Aventurine (Green Quartzite)

Silicon Dioxide (SiO2) with inclusions of Fuchsite (K(Al,Cr)2(AlSi3O10)(OH)2)

Sodalite

Na8(Al6Si6O24)Cl2

Quartzite

Quartzite (primarily SiO2)

Green Aventurine

Quartz variety (SiO2 with inclusions)

Quartzite Pebble

Metamorphosed Quartz Sandstone (SiO2)