Rock (Likely Sedimentary)

Sandstone (likely Quartzose)

Arenite (SiO2 principal mineral)

Chert (Iron-stained)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Petrified Wood

Silicified Wood (primarily SiO2)

Geode with Quartz and Chalcedony

Silicon Dioxide (SiO2)

Weathered chert or silicified limestone nodule

Microcrystalline quartz (SiO₂), possibly replacing limestone; exact identification requires testing

Weathered reddish-brown rock fragment

Probably altered basalt or fine-grained volcanic rock; exact identification requires testing

Sandstone (Ferruginous)

Arenite (with Hematite/Limonite cement)

Sandstone (likely Arkosic)

Arenite (SiO2 based)

Chert or flint fragment

Microcrystalline quartz (SiO₂), likely silicified rock

Coal (likely Bituminous or Lignite)

Organic Sedimentary Rock (Carbonaceous)

Rounded gray river pebble, likely fine-grained sandstone or siltstone

Indeterminate clastic sedimentary rock; possibly quartz-rich sandstone or siltstone

Chert (Flint variety)

Chert (SiO2)

Tumbled kambaba jasper (likely)

Kambaba jasper, a silica-rich microcrystalline quartz aggregate, commonly containing fossilized cyanobacterial structures and dark green amphibole/pyroxene minerals

Agate

Chalcedony (SiO2) with impurities

Rounded beach pebble

Lithology indeterminate; likely fine-grained sandstone, mudstone, or weathered volcanic rock

Limestone with Chert or Siltstone bands

Sedimentary carbonate rock (CaCO3) often with siliceous impurities

Likely foliated metamorphic rock, possibly schist

Mica schist or micaceous quartzite; exact identification is uncertain from the photograph

Sandstone (likely Arkosic or Lithic Sandstone)

Arenite (SiO2 based with mineral inclusions)

Sandstone (likely Quartzose Sandstone)

Arenite (composed primarily of SiO2)

River Pebble (Likely Chert or Fine-Grained Sandstone/Quartzite)

Siliciclastic clast (likely Chert or Quartzarenite/Quartzite pebble)

Sandstone (Grooved/Weathered)

Arenite (composed primarily of Quartz and Lithic fragments)

Rough Agate/Chert Nodules

Cryptocrystalline Quartz (SiO2)

Rounded gray-brown river cobble

Indeterminate lithology; possibly weathered quartzite, chert, or fine-grained sandstone

Banded Siltstone

Siltstone with planar bedding

Sandstone (likely Arkose or Lithic)

Clastic sedimentary rock (SiO2 + impurities)

Sandstone (likely a river or beach pebble)

Sandstone (a clastic sedimentary rock)

Coal (most likely Bituminous or Anthracite)

Coal (organic sedimentary rock)

Fossilized Brachiopod

Phylum Brachiopoda (likely Order Spiriferida or Orthida)

Pyrite-bearing metamorphic rock (likely schist or gneiss)

Pyrite (FeS₂) in a quartz–mica-rich host rock

River Cobbles (Quartzite and Sandstone)

Metamorphosed Quartz-rich Sedimentary Rock

Chert (River Siltstone/Quartzite type)

Microcrystalline Quartz (SiO2)

Chert (Jasper/Agate variety)

Microcrystalline Quartz (SiO2)

Greenish Metamorphic Rock (likely containing epidote or chlorite)

Metamorphic rock, possibly epidosite or greenstone

Rounded gray pebble

Indeterminate; likely a water-worn silicate or carbonate pebble

Chert (Yellow Jasper/Flint)

Microcrystalline Quartz (SiO2)

Quartzite Geode (unopened)

SiO2 (Silicon Dioxide)

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Granite pebble

Granite, typically quartz–feldspar–mica aggregate

Weathered sandstone fragment

Quartz-rich sandstone, likely ferruginous sandstone

Sandstone (likely Ferruginous)

Arenite with Iron Oxide cement

Sandstone (likely Quartzose Sandstone)

Arenite (SiO2 principal composition)

Chert (Flint/Jasper variety)

Microcrystalline Quartz (SiO2)