Industrial Byproduct (Anthropogenic Rock Like Material)

Red Sandstone

Arenite (primarily Quartz with Hematite cement)

Chert (Arrowhead/Projectile Point)

Microcrystalline quartz (SiO2)

Sandstone

Arenite (SiO2 primarily)

Chert (Arrowhead Fragment)

Microcrystalline Quartz (SiO2)

Limestone

Calcium Carbonate (CaCO3)

Gravel and Sediment Sample

Mixed clastic sediment

Quartzite

Quartzite (primarily SiO2)

Yellow Calcite

Calcium Carbonate (CaCO3)

Quartz Pebble

Silicon Dioxide (SiO2)

Unakite-like jasper / epidote–feldspar rock

Epidote–feldspar–quartz aggregate; commonly marketed as unakite or brecciated jasper

Likely weathered metallic mineral or slag fragment

Indeterminate; possibly iron-rich sulfide/oxide material or industrial slag

Quartz (Milky/River Quartz)

Silicon Dioxide (SiO2)

Vesicular Basalt (Lava Rock)

Vesicular Basalt

Tektite (likely indochinite)

Natural silica-rich impact glass; predominantly amorphous SiO₂ with aluminum, iron, magnesium, calcium, and sodium

Basalt (Weathered)

Extrusive Igneous Rock (Mafic composition)

Chert (Yellow Jasper)

Cryptocrystalline Quartz (SiO2)

Bauxite

Bauxite (Mixture of Al(OH)3, AlO(OH), and Fe2O3)

Quartz Sand Gravel

Silicon Dioxide (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Chert (specifically Flint or Dark Chert)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Quartzite

Quartzite (primarily SiO2)

Chert (Yellow Jasper variant)

Microcrystalline Quartz (SiO2)

Quartz Vein in Metamorphic Rock

Silicon Dioxide (SiO2) within Metasedimentary host

Fulonite (Fulgurite-like)

Fulgurite (SiO2 fused silica/lechatelierite)

Silver (Morgan Dollar)

Native Silver (Ag) - 90% Silver, 10% Copper alloy

Chalcanthite

Hydrated copper(II) sulfate (CuSO4·5H2O)

Chert Arrowhead

Cryptocrystalline Quartz (SiO2)

Quartzite Pebble

Quartzite (SiO2)

Coquina (Fossiliferous Limestone)

Biogenic Limestone (Calcium Carbonate, CaCO3)

Sea Shell Fragment (Calcium Carbonate)

Aragonite / Calcite (CaCO3)

Small pale rock fragment

Indeterminate; possibly quartz, calcite, or a weathered feldspar-rich fragment

Sandstone (Weathered Pebble)

Arenite (SiO2 primarily)

Quartzite

Quartzite (primarily SiO2)

Anthracite Coal

Anthracite (Carbon C)

Sea Glass

Man-made silicate glass weathering product

Red Jasper (Quartz)

Silicon Dioxide (SiO2) with Iron impurities

Quartzite

SiO2 (Metamorphosed Sandstone)

Petrified Wood

Fossilized wood / Silicified wood

River Pebble (Gravel)

Clastic sedimentary rock (likely Siltstone or Mudstone pebble; SiO2 with various impurities)

Tumbled amber-colored chalcedony or jasper

Microcrystalline quartz (SiO₂), likely iron-stained chalcedony/jasper

Diamond (in Matrix)

Carbon (C)

Quartzite

Quartzite (SiO2)