Rock (Likely Sedimentary)

Sandstone (lithic/greywacke variant)

Clastic sedimentary rock (primarily SiO2 with rock fragments)

Conglomerate (or Breccia)

Clastic Sedimentary Rock (Conglomeratic)

Petrified Wood

Silicified Paleoxylon (SiO2)

Sandstone (with Iron concretions/staining)

Arenite (composed primarily of Quartz and Feldspar with Iron Oxide cement)

Polished dark pebble, possibly basalt or chert

Uncertain; likely fine-grained basalt (plagioclase–pyroxene) or microcrystalline silica (chert)

Sandstone

Arenite (SiO2 primarily)

Sandstone

Arenite (primarily SiO2)

Chert (Flint / Jasper)

Silicon Dioxide (SiO2)

Sandstone

Arenite (SiO2 based)

Sandstone

Arenite (Siliclastic Sedimentary Rock)

Metallic sulfide ore, likely galena-bearing rock

Galena (lead sulfide, PbS), possibly with pyrite or other sulfides

Quartz-rich pegmatite (likely feldspar–quartz rock)

Granitic pegmatite; predominantly quartz (SiO₂) and feldspar, with possible mica and iron-oxide staining

Quartz-rich pegmatite (likely feldspar–quartz rock)

Granitic pegmatite; chiefly quartz (SiO₂) and feldspar, with minor mica and dark accessory minerals

Tumbled dark banded stone, possibly indigo gabbro or banded basalt

Indeterminate; likely fine-grained mafic rock composed mainly of plagioclase and pyroxene, with possible amphibole or alteration minerals

Tumbled quartz-rich rock, possibly jasperized quartz or quartzite

Quartz (SiO₂), likely with iron-oxide staining and minor feldspar or other silicate minerals; exact identification is uncertain from the photograph

Tiger's Iron

Pseudomorphic Quartz Aggregate (contains SiO2 with Fe2O3 and FeOOH)

River Stone (likely Quartzite or Sandstone)

Metamorphosed Quartz-rich Rock (SiO2)

Pale green tumbled mineral fragment, likely serpentine or green calcite

Probable serpentine-group mineral (Mg3Si2O5(OH)4) or, less likely, calcite (CaCO3); identification is uncertain from the photograph

Tumbled Agate

Silicon Dioxide (Chalcedony variety), SiO2

Tumbled brown stone, likely jasper or iron-stained quartz

Microcrystalline quartz (SiO₂), possibly chalcedony/jasper with iron-oxide inclusions

Tumbled jasper or chalcedony pebble

Microcrystalline quartz, SiO₂ (likely jasper/chalcedony)

Weathered Sandstone

Quartz Arenite / Clastic Sedimentary Rock

River Rocks (Black)

Various lithologies (e.g., basalt, chert, obsidian for black varieties), mechanically rounded clasts

Likely anthracite coal

Anthracite; predominantly carbon (C), with minor mineral impurities

Coal (likely Anthracite)

Anthracite coal

Sandstone

Sedimentary rock composed mainly of quartz sand

Granite Pebble (Salt and Pepper Granite)

Felsic Intrusive Igneous Rock (Granite)

Druzy Quartz on Host Rock

Silicon Dioxide (SiO2)

Sandstone or Weathered Conglomerate

Sedimentary Rock (Quartzose Sandstone / Lithic Arenite)

Halite

Sodium Chloride (NaCl)

Fossilized tooth, likely mammalian molar

Indeterminate Mammalia; mineralized dentine and enamel

Sandstone (Quartz-rich)

Arenite

Tumbled blue calcite

Calcite (CaCO₃), likely blue variety

Blue calcite

Calcite (CaCO₃), likely blue variety

White Chalcedony

Silicon Dioxide (SiO2)

Chert (Flint)

Silicon dioxide (SiO2)

Fossil Shell

Brachiopod or Mollusk fossil

Jasper

Microcrystalline Quartz (SiO2)

Jasper

Microcrystalline Quartz (SiO2)

Fossiliferous Limestone with Crinoid Stem

Sedimentary Rock with Echinodermata fossil fragment

Chert (often called Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert

Silicon dioxide (SiO2)