Organic (Sedimentary Context)

Chert (Flint)

Silicon Dioxide (SiO2)

Brown chert (possible jasper)

Microcrystalline quartz (SiO₂), with iron-oxide coloring

Fossil oyster shell

Fossilized bivalve shell; likely an oyster (Ostreidae), species indeterminate

Chert / Flint (Artifact)

Microcrystalline Quartz (SiO2)

Sandstone

Arenite (primarily Quartz Sandstone)

Nutting Stone / Cupstone (Sandstone or Quartzite)

Sedimentary rock with anthropogenic modification (cupule)

Quartz-rich rock fragment

Unidentified quartz–feldspar-rich rock; exact lithology cannot be determined from the image

Chert / Flint Tool

Cryptocrystalline quartz (SiO2)

Chert / Flint Arrowhead

Microcrystalline Quartz (SiO2)

Tumbled limestone or marble

Calcite-rich carbonate rock; likely limestone (CaCO₃), possibly marble

Glauconitic Sandstone (or Greenstone)

Glauconitic Sandstone with Quartz

Stromatolite (stromatolitic limestone)

Laminated microbial carbonate, chiefly calcite (CaCO₃); precise species or age cannot be determined from the photo

Generic Pebble / Rock Fragment

Lithic fragment / Weathered rock pebble

Chert (flint) fragment

Microcrystalline quartz (SiO₂), commonly called chert; “flint” is a variety of chert

Chert (Arrowhead Fragment)

Silicon Dioxide (SiO2)

Pyrite (fool’s gold)

Pyrite, FeS₂ (iron disulfide)

Chert or chalcedony nodule

Microcrystalline quartz (SiO₂), possibly weathered chert

Pyrite in Matrix (likely Quartz or Schist matrix)

Iron Sulfide (FeS2)

Fossil shell fragment

Likely a marine gastropod or bivalve shell; original shell material was calcium carbonate (aragonite or calcite)

Flint (chert) hand axe

Cryptocrystalline silica (SiO₂), worked into a bifacial stone tool

Chert / Flint Arrowheads

Cryptocrystalline Quartz (SiO2)

Chert (often called Flint in archaeological contexts)

Silicon Dioxide (SiO2)

Likely water-worn bone or fossil fragment

Indeterminate fossilized bone; species and age cannot be determined from the image

Fossil coral

Colonial coral fossil; exact taxon cannot be determined from the image

Goethite pseudomorph after Pyrite

Goethite (FeO(OH)) pseudomorph after Pyrite (FeS2)

Fossilized shell or small fossil fragment

Indeterminate fossil; possibly a partial gastropod or bivalve, mineralized with calcite

Weathered pale-blue rock fragment

Unidentified; the image does not show enough detail for a reliable geological identification

Flint (chert) with a flint knapping flake

Microcrystalline quartz (SiO₂), commonly called flint or chert

Flint (chert)

Microcrystalline quartz (SiO₂), variety of chert

Weathered quartz-rich rock, possibly chert or quartzite

Likely microcrystalline quartz (SiO₂), but exact identification is uncertain from the photograph

Sandstone (Ferruginous)

Arenite (primarily SiO2 with Fe2O3 cement)

Hematite (Tumbled)

Iron(III) oxide (Fe2O3)

Orange Calcite

Calcium Carbonate (CaCO3)

Fossil bivalve shell

Fossilized or partially mineralized bivalve; exact genus cannot be determined from the image

Potassium-Rich Silicate Clay (inferred from biological context)

Phyllosilicate group (likely Illite or Smectite within surrounding soil substrate)

Hag Stone

Perforated Sedimentary Rock (typically Sandstone or Siltstone)

Sandstone (likely Ferruginous)

Sandstone (SiO2 with iron oxides)

Possible fossilized bone fragment

Indeterminate vertebrate bone; no taxonomic identification is possible from the image alone

Weathered sandstone fragment

Quartz-rich sandstone, possibly ferruginous sandstone

Polymictic conglomerate

Lithified polymictic conglomerate; clasts likely quartzite, granite, and volcanic rock in a dark matrix

Fossil-bearing limestone with a disc-shaped fossil

Calcareous sedimentary rock containing an unidentified fossil; precise fossil identification is not possible from the image

Ferruginous Sandstone

Ferruginous Sandstone (Quartz Arenite with Iron Oxide cement)