Organic (Sedimentary Context)

Glauconitic Sandstone (or Greenstone)

Glauconitic Sandstone with Quartz

Chert / Flint Tool

Cryptocrystalline quartz (SiO2)

Chert / Flint Arrowhead

Microcrystalline Quartz (SiO2)

Generic Pebble / Rock Fragment

Lithic fragment / Weathered rock pebble

Flint (chert) hand axe

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

Chert (Arrowhead Fragment)

Silicon Dioxide (SiO2)

Chert or chalcedony nodule

Microcrystalline quartz (SiO₂), possibly weathered chert

Pyrite in Matrix (likely Quartz or Schist matrix)

Iron Sulfide (FeS2)

Chert / Flint Arrowheads

Cryptocrystalline Quartz (SiO2)

Weathered quartz-rich rock, possibly chert or quartzite

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

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

Hag Stone

Perforated Sedimentary Rock (typically Sandstone or Siltstone)

Weathered pale-blue rock fragment

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

Fossil bivalve shell

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

Sandstone or Quartzite with algae

Unknown specific, largely SiO2 with biological growth

Chert (often called Flint in archaeological contexts)

Silicon Dioxide (SiO2)

Sandstone (Ferruginous)

Arenite (primarily SiO2 with Fe2O3 cement)

Hematite (Tumbled)

Iron(III) oxide (Fe2O3)

Orange Calcite

Calcium Carbonate (CaCO3)

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

Small pale stone, possibly quartz or limestone

Indeterminate from image; likely quartz (SiO₂) or calcite-rich limestone (CaCO₃)

Sandstone (likely Ferruginous)

Sandstone (SiO2 with iron oxides)

Potassium-Rich Silicate Clay (inferred from biological context)

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

Ferruginous Sandstone

Ferruginous Sandstone (Quartz Arenite with Iron Oxide cement)

Fossilized bone or tooth fragment

Mineralized vertebrate bone; exact taxon indeterminate from image

Sandstone (Water-worn Cobble)

Arenite (variable composition, primarily SiO2)

Bivalve Fossil (Clam)

Class Bivalvia (e.g., Mercenaria or similar genus), composed of CaCO3 (Aragonite/Calcite)

Chert (specifically Flint or Dark Chert)

Silicon Dioxide (SiO2)

Fossilized bone fragment, possibly mammalian long bone

Mineralized bone (commonly apatite, Ca₅(PO₄)₃(OH,F,Cl), replacing original bone)

Red Jasper

Silicon Dioxide (SiO2) with Iron inclusions

Exposed aggregate concrete (stone-chip surface)

Portland-cement concrete containing natural aggregate; not a natural rock

Ironstone Concretion (Moqui Marble type)

Ironstone Concretion (Fe2O3 with SiO2 core)

Jasper Marble

Silicon Dioxide (SiO2) with Impurities

Black Jasper

Silicon dioxide (SiO2) with carbon/mineral inclusions

Fossiliferous Limestone with Crinoid Stem fragment

Calcite (CaCO3) containing Crinoidea fossils

Unidentified Rock Fragment

Unknown

Red Jasper

Silicon Dioxide (SiO2) with Hematite inclusions

Chalcedony / milky quartz flake

Microcrystalline quartz (SiO₂), likely chalcedony; possibly a worked quartzite or chert fragment

Flint or chert flake/tool

Microcrystalline quartz (chalcedony), SiO₂

Yellow Jasper

Silicon Dioxide (SiO2)