Mineral Precipitate (Anthropogenic Context)

Chert (River Pebble)

Microcrystalline Quartz (SiO2)

Chert Arrowhead (Projectile Point)

Microcrystalline Quartz (Chert or Flint)

Chert (Arrowhead/Projectile Point)

Cryptocrystalline Quartz (SiO2)

Ammonite fossil

Ammonoidea (likely an involute ammonite; exact genus requires preparation and context)

Limestone

Calcium Carbonate (CaCO3)

Graywacke

Graywacke

Hematite

Iron(III) oxide (Fe2O3)

Quartz Vein Rock

Silicon dioxide (SiO2) within a host rock matrix

Ferruginous Sandstone (Ironstone Conglomerate fragments)

Ferruginous clastic sedimentary rock (SiO2 cemented by Fe2O3)

Weathered orange-brown stone, possibly iron-stained sandstone

Unconfirmed; likely quartz-rich sandstone with iron-oxide staining

Blue Aventurine

Quartz (SiO2) with inclusions

Milky Quartz

Silicon Dioxide (SiO2)

Black Star Diopside

Diopside (CaMgSi2O6) with Magnetite inclusions

Slag (Industrial Glass)

Anthropogenic Vitreous Slag (Post-industrial byproduct)

Cobalt Blue Slag Glass

Amorphous Silicon Dioxide (anthropogenic) with Cobalt additives

Hematite (likely Botryoidal or Specularite variant)

Iron(III) oxide (Fe2O3)

Native Copper Nugget

Native Copper (Cu)

Likely brown chert (flint)

Microcrystalline quartz (SiO₂), variety chert/flint

Limonite / Ironstone

Hydrated ferric oxide (FeO(OH)·nH2O)

Chert Nodule

Microcrystalline Silica (SiO2)

Gneiss (specifically a water-worn pebble)

Gneiss

Pyrite in Quartz Matrix

Iron Sulfide (FeS2) embedded in Silicon Dioxide (SiO2)

Baryte (Barite)

Barium sulfate (BaSO4)

Iron-rich concretion (possibly limonite/goethite)

Limonite, a mixture of iron oxyhydroxides, commonly including goethite (α-FeO(OH))

Weathered sandstone or iron-rich sedimentary fragment

Quartz-rich sandstone, possibly ferruginous sandstone (SiO₂-dominant)

Chert (varietal Chalcedony or Flint)

Silicon dioxide (SiO2) - Microcrystalline Quartz

Sandstone (Ferruginous)

Arenite (SiO2 based with Fe2O3 banding)

Possible iron-oxide concretion with a dark mineral cap

Iron-oxide–cemented sedimentary concretion; exact composition cannot be determined from the image

Weathered basalt pebble

Basalt, a fine-grained mafic volcanic rock composed mainly of plagioclase feldspar, pyroxene, and commonly olivine

Quartz geode

Quartz (SiO₂), with a chalcedony/agate rind

Rounded sandstone pebble

Clastic sandstone, chiefly quartz and feldspar grains cemented by iron oxides and silica

Likely basalt fragment

Basalt; fine-grained mafic volcanic rock, chiefly plagioclase and pyroxene with possible olivine

Chert (with nodule)

Microcrystalline Quartz (SiO2)

Possible calcite crystal fragment

Calcite (CaCO₃), tentative identification

Grooved Maun Ball (Maul/Hammerstone-like Concretion)

Calcareous/Ferruginous Concretion in Sandstone Matrix

Chert (Arrowhead Debitage or Flake)

Microcrystalline silica (SiO2)

Banded chert or agate

Microcrystalline quartz (chalcedony), SiO₂

Ironstone (iron-oxide-rich rock)

Ferruginous sandstone or ironstone; likely composed chiefly of goethite and/or limonite, with quartz and clay

Possible basalt or other dark volcanic rock

Undetermined fine-grained mafic volcanic rock; basalt is a possibility

Scoria (vesicular volcanic rock)

Basaltic to andesitic scoria; chiefly plagioclase, pyroxene, and volcanic glass

Chert (Arrowhead variety)

Chert (SiO2)

Red Jasper

Silicon Dioxide with Iron Oxide inclusions (SiO2 + Fe2O3)