Sedimentary Like (Industrial Composite)

Diamond (or diamond simulant)

C

White Chalcedony (Agate)

Silicon Dioxide (SiO2)

Tumbled quartz-like pebble

Quartz (silicon dioxide, SiO₂), possibly iron-stained chalcedony

Marble

Recrystallized Calcite (CaCO3) or Dolomite (CaMg(CO3)2)

Quartz (Double-Terminated)

Silicon Dioxide (SiO2)

Chert (and Flint variant)

Microcrystalline Quartz (SiO2)

Siltstone or Fine-grained Sandstone pebble

Siltstone (primarily SiO2 with clay minerals)

Quartz River Pebbles

Silicon Dioxide (SiO2)

White quartz in dark matrix (likely quartz-bearing breccia or polished composite specimen)

Quartz, SiO₂, in an unidentified dark silicate matrix

Chalcedony

Cryptocrystalline Quartz (SiO2)

Polished banded jasper pebble

Jasper, a microcrystalline quartz variety (SiO₂), with iron-oxide and clay/mineral impurities

Likely raw garnet fragment

Garnet-group silicate, commonly almandine (Fe₃Al₂Si₃O₁₂)

Chert (Commonly known as Flint)

Microcrystalline Quartz (SiO2)

Pyrite

Iron Sulfide (FeS2)

Quartz Geode

Silicon Dioxide (SiO2)

Orange Calcite

Calcium Carbonate (CaCO3)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Rounded iron-rich pebble

Likely ferruginous sandstone or ironstone pebble; exact identification requires testing

Shale or Siltstone

Sedimentary Clastic Rock (Variable mineral composition including quartz and clay minerals)

Sandstone (Ferruginous)

Arenite (primarily SiO2 with Fe2O3 inclusions)

Chert (Grey-Green Var.)

Silicon Dioxide (SiO2)

Chert (Yellow Jasper)

Microcrystalline Quartz (SiO2)

Orange Quartzite (River Pebble)

Quartzite (primarily SiO2)

Slag Glass / Industrial Slag

Anthropogenic Glass

Fossil oyster shell

Exogyra sp. or a related fossil oyster; largely calcitic shell (CaCO₃)

Polished banded jasper

Jasper, microcrystalline quartz (SiO₂) with iron-oxide inclusions

Chert (Jasper/Flint variant)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (specifically a nodule with Chalcendony/Agate banding)

Microcrystalline Quartz (SiO2)

Weathered limestone fragment

Limestone, composed primarily of calcite (CaCO₃)

Clear Quartz

Quartz (Silicon Dioxide, SiO2)

Tumbled orbicular jasper

Orbicular jasper; microcrystalline quartz (SiO₂) with iron oxides and feldspathic/chalcedony inclusions

Turquoise-style beaded bracelet

Turquoise, hydrated copper–aluminum phosphate: CuAl₆(PO₄)₄(OH)₈·4H₂O; possibly dyed or composite beads

Anthracite Coal

Anthracite (Carbon based)

Fossil bivalve impression in chert or siliceous limestone

Likely fossilized bivalve mold/cast; host possibly silicified limestone or chert

Fossil oyster shell

Fossilized bivalve, commonly Ostrea or Crassostrea

Chalcedony (Common Opal/Chert variety)

Silicon Dioxide (SiO2)

Red Sandstone

Arenite (Ferruginous Sandstone)

Red Shale

Lutite (primarily composed of Hydrous Aluminum Silicates with Hematite staining)

Chalcedony (Agate/Carnelian variety)

Cryptocrystalline Quartz (SiO2)

Blue Slag Glass

Anthropogenic Amorphous Silicon Dioxide

Chert (Yellow Jasper)

Silicon Dioxide (SiO2)

Garnet

Garnet Group (Silicate Minerals)