Chert (or Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Category
Anthropogenic (Man Made Material)
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Sandstone
Arenite (composed primarily of SiO2)
sedimentary
Quartzite
Quartzite (primarily SiO2)
metamorphic
Limestone
Limestone (Calcium Carbonate, CaCO3)
Sedimentary
Fossilized Bone Fragment
Petrified Osseous Material
fossil
Petrified Wood
Silicified Wood (primarily SiO2)
sedimentary
Diamond
Carbon (C)
gemstone
Chert
Microcrystalline Quartz (SiO2)
sedimentary
Banded gneiss pebble
Biotite–quartz–feldspar gneiss (composition variable)
metamorphic
Petrified wood
Silicified wood, chiefly microcrystalline quartz (SiO₂)
fossil
Tumbled jasper or rhyolitic porphyry
Silicic volcanic rock, likely rhyolite (quartz- and feldspar-rich), possibly jasperized
igneous
Serpentine
Serpentine group ((Mg,Fe,Ni,Al,Zn,Mn)3(Si,Al)2O5(OH)4)
metamorphic
Mudstone
Argillite / Siliciclastic sedimentary rock
sedimentary
Quartz / Quartzite
Silicon Dioxide (SiO2)
Mineral / Metamorphic
Sandstone
Arenite (primarily SiO2)
sedimentary
Sandstone (Tumbled/River Pebble)
Arenite (composed primarily of SiO2)
sedimentary
Limestone
Calcite (CaCO3)
sedimentary
Tumbled blue-dyed stone, likely basalt or blue aventurine
Likely fine-grained basalt (plagioclase and pyroxene), possibly coated or dyed; exact identification requires testing
igneous
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Sandstone (Ferruginous)
Arenite with Iron Oxide matrix
sedimentary
Petrified Wood
Petrified Wood (Silicified Wood)
fossil
Chert (or possibly Flint)
Chert (variant: Flint)
Sedimentary
Tumbled green jasper (probable serpentine-rich stone)
Jasper, microcrystalline quartz (SiO₂), possibly mixed with serpentine or chlorite
mineral
Limestone
Sedimentary rock composed mainly of calcium carbonate (CaCO3)
sedimentary
Chert or Chalcedony
Microcrystalline Quartz (SiO2)
sedimentary
Petrified Wood
Silicified Wood (SiO2)
fossil
Jasper
Silicon Dioxide (SiO2)
mineral
Chert Pebble
Microcrystalline Quartz (SiO2)
sedimentary
Mudstone
Lutylite (group of fine-grained sedimentary rocks)
sedimentary
Fossilized Stingray Mouth Plate
Myliobatidae gen. et sp. indet. (e.g., Myliobatis, Aetobatus)
fossil
Petoskey Stone
Hexagonaria percarinata
fossil
Pyrite
Iron Disulfide (FeS2)
mineral
Polished tiger’s-eye cabochon (probable)
Quartz variety, SiO₂, with fibrous riebeckite/crocidolite-derived inclusions
metamorphic
United States Quarter Dollar
Cupronickel Clad Alloy (75% Copper, 25% Nickel over a 100% Copper core)
Metal / Man-made mineral-like object
Petrified Wood
Silicified Wood (SiO2)
fossil
Petrified Wood
Silicified wood (Quartz/Chalcedony replacement of cellulose)
fossil
Quartzite
Quartz-rich metamorphic rock; chiefly SiO₂
metamorphic
Biotite schist (likely graphite-bearing)
Mica schist; chiefly quartz + biotite mica, with possible graphite and feldspar
metamorphic
Coquina / Limonite-stained Limestone
Sedimentary Limestone with Iron Oxyhydroxide (FeO(OH)·nH2O)
sedimentary
Petrified Wood
Silicified Wood (SiO2 as Quartz/Chert/Chalcedony)
sedimentary
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
Likely weathered quartz-rich stone or fossil fragment
Indeterminate; possibly quartz-bearing sandstone, iron-stained quartz, or a fragmentary fossil
mineral