Anthropogenic (Man Made Material Mimicking Sedimentary Rock)

Chert (specifically Gray/Tan Bedded Chert)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Jasper/Flint variety)

Microcrystalline quartz (SiO2)

Chert (Cherty Flint/Jasper variety)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Chert Nodule

Chert (Microcrystalline Silicon Dioxide, SiO2)

Rounded iron-rich pebble

Likely hematite/goethite-bearing quartzite or ironstone; exact identification requires testing

Red Jasper

Jasper (SiO2) with Hematite (Fe2O3) inclusions

Red Jasper

Jasper (Silicon Dioxide, SiO2 with Fe2O3 inclusions)

Sandstone (Red Flagstone)

Clastic sedimentary rock (primarily Quartz - SiO2)

Weathered quartz-rich rock, likely sandstone or quartzite

Quartz arenite (sandstone) or quartzite; predominantly SiO₂

Banded Gneiss (River Cobble)

Gneiss (a high-grade metamorphic rock)

Limestone

Calcium Carbonate (CaCO3)

Weathered sandstone or siltstone

Clastic sedimentary rock, chiefly quartz and feldspar grains cemented by clay, silica, or iron oxides

Chert (Jasper/Agate variety)

Microcrystalline quartz (SiO2)

Petrified Wood

Silicified Wood (SiO2)

Chert (Jasper variety)

Microcrystalline quartz (SiO2)

Chert (specifically Flint or Jasper variant)

Cryptocrystalline Quartz (SiO2)

Likely foliated metamorphic rock, possibly schist

Mica schist or micaceous quartzite; exact identification is uncertain from the photograph

Rounded gray river pebble, likely fine-grained sandstone or siltstone

Indeterminate clastic sedimentary rock; possibly quartz-rich sandstone or siltstone

Red Jasper

Microcrystalline Quartz (SiO2 with Iron Oxide impurities)

Chert (Flint)

Chert (SiO2)

Sandstone

Arenite

Tumbled yellow jasper (likely serpentine or calcite-rich stone)

Jasper: microcrystalline quartz (SiO₂); exact yellow veining may indicate serpentine, calcite, or iron oxides

Chert (Quartz Pebble)

Silicon Dioxide (SiO2)

Small rounded pebble

Indeterminate lithic grain; likely weathered sandstone, iron-stained quartz-rich rock, or a concretion

Ironstone with Pyrite

Ferruginous Sandstone (Fe2O3) with minor Sulfide minerals (FeS2)

Petrified Wood

Silicified Wood (primarily SiO2)

Chert (Flint variety)

Chert (SiO2)

Fossil Coral

Coral Limestone (a type of biogenic sedimentary rock)

Chert Cobble / Quartzite River Stone

Microcrystalline Quartz (SiO2) / Quartzite

Rounded gray stone, likely quartz-rich granitic rock

Probable granite or granitic gneiss; mainly quartz, feldspar, and mica

Greywacke Siltstone Pebble / Concretionary River Pebble

Siltstone / Argillite (Fine-grained Sedimentary Rock)

Brown chalcedony (likely carnelian/iron-stained quartz)

Microcrystalline quartz, SiO₂; brown coloration from iron oxides/hydroxides

Gneiss (Gneissic Granite Pebble)

Metamorphic rock rich in Quartz, Feldspar, and Mica

Petrified Wood

Silicified Wood (SiO2)

Petrified Wood

Silicified wood (Quartz/Chalcedony/Opal)

Turquoise

CuAl6(PO4)4(OH)8·4H2O

Petrified Wood (Black / Carbonized)

Silicon Dioxide (Quartz/Chalcedony replacing Organic Matter)

Coal (most likely Bituminous or Anthracite)

Coal (organic sedimentary rock)

Chert (varietal: Jasper or Flint)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Mixed rock and mineral collection

Multiple specimens; visible pieces may include quartz, calcite, agate/chalcedony, jasper, and dyed or coated materials

Chalcedony Agate / Carnelian nodules in Matrix

SiO2 (Silicon Dioxide) with iron oxide inclusions

Banded Chert (Ironstone/Jasper)

Cryptocrystalline Quartz (SiO2) with Iron Oxides