Mineral Precipitate (Anthropogenic Context)

Hag Stone

Perforated Sandstone (composed of SiO2 and calcareous cement)

Worked flint/chert artifact

Microcrystalline quartz (chalcedony), SiO₂; likely a knapped flint or chert flake/core fragment

Weathered conglomeratic sandstone

Polymictic conglomerate or pebbly sandstone, likely iron-stained

Shale with Quartz Vein

Argillaceous Shale with Silicon Dioxide Vein

Orange Calcite

Calcite (Calcium Carbonate, CaCO3)

Ferruginous Quartz

Silicon Dioxide (SiO2) with Hematite/Limonite

Limonite/Ironstone

Limonite (FeO(OH)·nH2O)

Limonite (Iron Ore)

Limonite (FeO(OH)·nH2O)

Fired Clay Brick (Anthropic Rock substitute)

Anthropogenic polycrystalline ceramic (predominantly Mullite and Quartz: Al6Si2O13 + SiO2)

Limestone with Quartz or Calcite Veining

Calcium Carbonate (CaCO3) matrix with SiO2 or CaCO3 inclusions

Polymictic conglomerate

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

Limonite (Limonitic Sandstone)

Hydrated Iron(III) Oxide-Hydroxide ($FeO(OH)·nH_2O$)

Green sea glass or green glass-like tumbled material

Amorphous silicate glass; likely anthropogenic soda-lime glass, not a natural mineral

Blue Calcite

Calcium Carbonate (CaCO3)

Yellow Quartz

Silicon Dioxide (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Iron-stained quartz (possible citrine/vein quartz)

Quartz, SiO₂, colored by iron-oxide inclusions

Greenstone Celt (Polished Stone Axe)

Metamorphosed mafic rock (often Basalt or Diabase)

Glass / Silicon Dioxide (Man-made)

SiO2 (Amorphous Silicon Dioxide)

Basalt

Basalt (Mafic Extrusive Igneous Rock)

Carnelian

Chalcedony (SiO₂)

Dark weathered igneous rock, likely basalt

Basalt; chiefly plagioclase feldspar, pyroxene, and commonly olivine or iron oxides

Weathered iron-rich rock, likely basalt or ironstone

Probable weathered basalt (mafic silicate rock); exact identification requires a fresh surface and testing

Quartz Geode

Silicon Dioxide (SiO2) in a sedimentary host

Likely ironstone or ferruginous sandstone fragment

Iron-oxide-cemented sandstone; commonly quartz grains cemented by hematite/goethite (composition cannot be confirmed from the image)

Fine-grained gray rock, possibly basalt

Basalt (tentative; likely plagioclase–pyroxene rock)

Chert (specifically Flint or Dark Chert)

Silicon Dioxide (SiO2)

Banded Carnelian Agate

Silicon Dioxide (SiO2)

Gold in Quartz Matrix

Native Gold (Au) with Quartz (SiO2)

Ironstone concretion (possibly limonite/goethite-bearing)

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

Yellow Chert (Jasper)

Silicon Dioxide (SiO2)

Ferruginous Sandstone (with Laterite)

Ferruginous Arenite (FeO(OH)·nH2O)

Tumbled Hematite

Iron(III) oxide (Fe2O3)

Orange Calcite

Calcite (Calcium Carbonate, CaCO3)

River Cobble (likely Serpentinite or Greenstone)

Serpentinite / Greenschist facies rock

Kidney Stone (Urolith / Calcium Oxalate Stone)

Calcium Oxalate Monohydrate (Whewellite) / Calcium Oxalate Dihydrate (Weddellite)

Weathered granitic rock (likely granite or granodiorite)

Granite–granodiorite; mainly quartz, feldspar, and mica/hornblende

Magnetite

Magnetite (Fe3O4)

Black Jasper

Silicon dioxide (SiO2)

Orange Calcite

Calcite (Calcium Carbonate, CaCO3)

Jasper

SiO2

Yellow Quartz

Silicon Dioxide (SiO2)