Industrial Byproduct (Anthropogenic Material)

Chert (Field Stone)

Microcrystalline Quartz (SiO2)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Chert (Arrowhead Artifact)

Chert (SiO2)

Chert (Gravel)

Microcrystalline Quartz (SiO2)

Quartzite

Quartzite (SiO2)

Raw Diamond (Rough Uncut)

Diamond (C - pure carbon)

Milky Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Nuummite

Nuummite (intergrowth of orthoamphiboles Anthophyllite and Gedrite, (Mg,Fe)7Si8O22(OH)2)

Petrified Wood

Silicified Wood (primarily SiO2)

Precious Opal

Hydrated Silica (SiO2·nH2O)

Stichtite in Serpentine (Atlantisite)

Mg6Cr2CO3(OH)16·4H2O (Stichtite) within Mg3Si2O5(OH)4 (Serpentine)

Bivalve Fossil (Clam/Mollusk)

Class: Bivalvia (Order: Veneroida), Calcium Carbonate (CaCO3)

Chert (Flint variety)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Diamond

Diamond (C)

Green Aventurine and Clear Quartz

Green Aventurine (Silicon Dioxide - SiO2 with Fuchsite inclusions); Clear Quartz (Silicon Dioxide - SiO2)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Zebra Jasper

Silicon Dioxide (SiO2) with inclusions

Costume Jewelry with Synthetic Gemstones

Synthetic Cubic Zirconia and Glass (SiO2 / ZrO2)

Milky Quartz with Iron Staining

Quartz (Silicon Dioxide, SiO2)

Siltstone

Siltstone (composed of clastic quartz and feldspar)

Milky Quartz

Silicon Dioxide (SiO2)

Limestone

Calcium Carbonate (CaCO3)

Clear Quartz crystals on a Matrix base (Geode fragment)

Silicon Dioxide (SiO2)

Bicolor Quartz Pebble

Silicon Dioxide (SiO2) with mineral inclusions

Petrified Wood

Silicified Wood (SiO2)

Hematite

Iron(III) oxide (Fe2O3)

Sedimentary Breccia

Breccia (Clastic Sedimentary Rock)

Obsidian (Apache Tear)

Amorphous Volcanic Glass (SiO2)

Snowflake Obsidian

Volcanic glass containing Spherulitic Cristobalite (SiO2)

Snakeskin Agate

Agate (Cryptocrystalline Quartz, SiO2)

Opalite (a synthetic glass)

Silicon Dioxide (SiO2) with various additives; not a true mineral but a man-made gem simulant

Moss Agate

Silicon Dioxide (SiO2) with Manganese or Iron Oxide inclusions

Obsidian

Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)

River Stone (River Pebbles)

Alluvial Deposit (typically Quartzite, Sandstone, or Granite clasts)

Fossilized Bone Fragment

Permineralized Vertebrate Fossil (Hydroxyapatite replaced by Minerals)

Fossil Coral (Rugose Coral Fragment)

Rugosa (extinct order of solitary and colonial corals)

Gray Slate River Stone

Slate

Sandstone (Red Sandstone)

Arenite (predominantly SiO2 with Fe2O3 cement)

Diorite

Diorite (Intermediate intrusive igneous rock)

Quartzite

Quartzite (primarily SiO2)

Limestone

Calcium Carbonate (CaCO3)

Feldspathic Gneiss (Granite Gneiss)

Gneiss (High-grade Regional Metamorphic Rock)