Anthropogenic (Man Made Material Mimicking Sedimentary Rock)

Gravel / Small Pebble

Rock Fragment (Gravel)

Chert (and associated river cobbles)

Silicon dioxide (SiO2)

Chert (and/or Flint)

Chert (Cryptocrystalline variety of Quartz, SiO2)

Chert (Flint Arrowhead)

Silicon Dioxide (SiO2)

Sandstone

Arenite (primarily SiO2)

Chert (often called Flint)

Chert (SiO2)

Chert

Sedimentary cryptocrystalline quartz (SiO2)

Chert / River Pebble

Microcrystalline Quartz (SiO2)

Coquina and Oyster Fossil Rock

Coquina limestone (Calcium Carbonate, CaCO3) containing fossilized Crassostrea / bivalve shells

Red Sandstone

Arenite (Ferruginous Sandstone)

Goldstone (blue-goldstone–style glass) beads

Artificial aventurine glass, typically silica glass with copper inclusions; not a natural mineral

Chert (Jasper / Quartz pebble)

Microcrystalline Quartz (SiO2)

Unidentified polished dark gemstone cabochon

Possibly hematite, obsidian, jet, or dark agate; image insufficient for a definitive identification

Chert (often called Flint or Agate nodule)

Cryptocrystalline Quartz (SiO2)

Chert (Quartz Variety)

Chert (Silicon Dioxide, SiO2)

Chert (and Jasper/Chalcedony mixture)

Microcrystalline Quartz (SiO2)

Granite

Granite (felsic intrusive igneous rock)

Chert

Microcrystalline Quartz (SiO2)

Coquina

Biogenic Limestone (Calcite/Aragonite base, CaCO3)

Chert (or Flint)

Chert (cryptocrystalline quartz), SiO2

Bauxite

Bauxite (Al(OH)3, γ-AlO(OH), and α-AlO(OH))

Chert (Flinty variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Sandstone

Quartz Sandstone (predominantly)

Carnelian cabochon

Orange-red variety of chalcedony (microcrystalline quartz), SiO₂

Lapis lazuli and green-blue chalcedony jewelry

Lapis lazuli: lazurite-bearing metamorphic rock, chiefly lazurite (Na₃Ca(Al₃Si₃O₁₂)S) with calcite and pyrite; second stone: likely chrysoprase or green-blue chalcedony (microcrystalline quartz, SiO₂)

Chert (or Flint)

Chert (a cryptocrystalline variety of quartz, SiO2)

Granite

Granite (a common rock type, not a single mineral with a formula. Composed primarily of quartz, feldspar, and mica/amphibole).

Chert (often called Flint)

Microcrystalline Quartz (SiO2)

Shale (or Mudstone/Siltstone)

Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)

Tumbled orange chalcedony / jasper

Microcrystalline quartz, SiO₂, likely iron-stained chalcedony or quartz-rich jasper

Chert (Flint)

Microcrystalline Quartz (SiO2)

Fossil shark tooth in sediment

Likely fossilized shark tooth, possibly *Carcharhinus* or *Otodus*; exact identification requires the tooth’s full morphology and locality

Tumbled greenstone (likely serpentinite or green jasper)

Serpentinite, commonly dominated by serpentine-group minerals (Mg₃Si₂O₅(OH)₄); exact identification requires testing

Mudstone

Argillite / Siliciclastic sedimentary rock

Polished black stone carving, likely soapstone/steatite

Steatite (massive talc), Mg₃Si₄O₁₀(OH)₂; exact material cannot be confirmed from the image

Chert / Green Jasper

Silicon Dioxide (SiO2)

Sandstone

Clastic sedimentary rock (primarily SiO2)

Chert

Chert (microcrystalline quartz)

Coquina

Bioclastic Limestone

Rounded gray river pebble, likely fine-grained basalt or andesite

Basaltic-andesitic volcanic rock; commonly plagioclase feldspar, pyroxene, and minor iron oxides

Blue Goldstone

Synthetic Aventurescent Glass (Cobalt-doped soda-lime glass)

Chert

Microcrystalline Quartz (SiO2)