Metamorphic Or Igneous (Context Dependent)

Banded chert or agate

Microcrystalline quartz (chalcedony), SiO₂

Honey calcite (likely)

Calcite, calcium carbonate (CaCO₃)

Chalcedony Geode / Agate Nodule

Cryptocrystalline Quartz (SiO2)

Red Jasper

Silicon Dioxide with Iron Oxide inclusions (SiO2 + Fe2O3)

Cobaltian Calcite (Cobaltoan Calcite)

Cobalt-bearing Calcite (Ca,Co)CO3

Ferruginous Sandstone

Arenite with Iron-Oxide Cement (FeO(OH)·nH2O / Fe2O3)

Hag Stone

Perforated Sandstone (composed of SiO2 and calcareous cement)

Green Moonstone (Garnierite)

Nickel-bearing Magnesium Silicate (often a mix of Serpentine and Talc/Chlorite groups)

Gossan (Iron Hat) with Quartz and Chlorite

Limonite/Goethite-rich Gossan (FeO(OH)·nH2O) with inclusions of Quartz and Chlorite

Worked flint/chert artifact

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

Shale with Pyrite

Clastic sedimentary rock containing Iron Disulfide (FeS2)

Red Sandstone

Arenite (primarily composed of SiO2 with Fe2O3 cement)

Polished fire agate

Chalcedony (microcrystalline quartz, SiO₂) with iron-oxide inclusions

Chert or flint flake

Cryptocrystalline microcrystalline quartz (SiO₂), likely chert/flint

Banded iron formation fragment

Banded iron formation (BIF), composed mainly of hematite/magnetite and chert (SiO₂)

Polymictic conglomerate

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

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Fossilized bone fragment, possibly mammalian long bone

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

Chert (Arrowhead/Projectile Point)

Chert (Cryptocrystalline Quartz, SiO2)

Quartz (Iron-stained)

Silicon Dioxide (SiO2)

Zebra Jasper

Tetragonal Silicon Dioxide (Quartz) with impurities

Feldspar in Matrix

Feldspar group minerals in metamorphic or igneous matrix

Quartz (possibly milky quartz)

Quartz (Silica; SiO₂)

Pyrite on Quartz (Fool's Gold in Quartz)

Iron Sulfide (FeS2) on Silicon Dioxide (SiO2)

Small pale stone, possibly quartz or limestone

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

Fossilized cylindrical shell or bone fragment

Indeterminate biogenic carbonate or phosphatic fossil; possible fragment of a tubular shell (e.g., scaphopod) or hollow bone

Glass / Silicon Dioxide (Man-made)

SiO2 (Amorphous Silicon Dioxide)

Sea Shell (Fighting Conch Fragment)

Calcium Carbonate (CaCO3) - Strombus alatus fragment

Granite / Gneiss (Felsic Metamorphic or Igneous Rock)

Gneiss (or weathered Granite)

Likely ironstone or ferruginous sandstone fragment

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

Sandstone (Nut-stone / Cup-stone artifact)

Quartz Arenite / Worked Sedimentary Rock

Chert (specifically Flint or Dark Chert)

Silicon Dioxide (SiO2)

Diamond

C

Emerald

Beryl (Be3Al2(SiO3)6) with Chromium and/or Vanadium impurities

Amethyst geode

Quartz, SiO₂; purple variety: amethyst

River Cobble (Conglomerate context)

Unconsolidated Fluvial Alluvium (comprised of various lithologies like Quartzite, Granite, or Basalt)

Yellow Chert (Jasper)

Silicon Dioxide (SiO2)

Pyrite in Quartz

Iron Sulfide (FeS2) in Silicon Dioxide (SiO2)

Ferruginous Sandstone (with Laterite)

Ferruginous Arenite (FeO(OH)·nH2O)

Sandstone Concretion

Sandstone (Sedimentary Rock) with silica or calcite cement

Rounded sandstone pebble

Clastic sandstone, predominantly quartz (SiO₂) grains in a cementing matrix