Rock (Likely Sedimentary)

Sandstone (likely Arkosic)

Clastic Sedimentary Rock

Conglomeratic Sandstone

Clastic Sedimentary Rock

Gravel (mixed crushed stone)

Unidentified aggregate of crushed natural rock fragments

Banded gneiss

Foliated gneiss, likely quartz–feldspar–biotite gneiss

Shale (sub-type: Carbonaceous Shale)

Lutaceous Sedimentary Rock

Sandstone (Quartzite-rich)

Clastic sedimentary rock (SiO2 primary)

Shale

Fissile Siliciclastic Sedimentary Rock

Rounded pebble, likely fine-grained river stone

Unidentified lithic pebble; composition cannot be determined from the image

Stream-Rounded Shale or Mudstone

Argillaceous sedimentary rock

Unidentified small rocks or gravel

Painted Garden Rock

Coated Siltstone or Mudstone

Sandstone (likely Siltstone or fine-grained Sandstone)

Sedimentary Rock (Clastic)

Painted River Rock

Painted Quartzite or Smooth Siltstone

Fossil-bearing concretion, possibly containing a fossil shell or other organic inclusion

Calcareous concretion; exact fossil and host-rock composition are not identifiable from the image

Geode with Quartz and Iron Oxide

Silicon dioxide with iron oxide inclusions (SiO2)

Small red-brown mineral or rock fragment

Unidentified; possibly iron-oxide-rich jasper, garnet, or weathered sulfide

Quartz geode fragment

Quartz (SiO₂), lining a cavity in a silica-rich rock

Painted pebble, likely a smooth river stone

Unidentified fine-grained natural rock; exact lithology cannot be determined from the image

Small rounded pebble; specific identification uncertain

Indeterminate lithic fragment; mineral composition cannot be determined from the image

Small weathered rock fragment

Unidentified lithic fragment; composition cannot be determined from the image

Small rounded quartz-rich pebble

Likely quartz (SiO₂), possibly iron-stained or mixed with other minerals

Shale

Clastic sedimentary rock (primarily clay and silt minerals)

Fossil-bearing sedimentary rock (possible bone or shell fossil)

Unidentified fossiliferous sedimentary matrix; exact fossil and host rock cannot be determined from the image

River Stone (likely Siltstone or Mudstone)

Argillaceous Sedimentary Rock

Polished river pebble

Indeterminate; likely fine-grained quartz-rich sedimentary rock or weathered volcanic rock

Rounded weathered pebble

Likely fine-grained sandstone, siltstone, or weathered volcanic rock; exact identification is uncertain from the image

Conglomerate

Lithified, poorly sorted gravel; composition is uncertain from the image

Weathered brown rock fragment

Indeterminate; possibly iron-stained sandstone, mudstone, or weathered limestone

Green-gray stone pebble (not reliably identifiable from the image)

Undetermined; possibly a fine-grained sedimentary rock such as mudstone or siltstone

Siltstone or Mudstone

Argillaceous sedimentary rock

Small, rounded stone pebble

Unidentified natural pebble; the image does not show enough detail to identify its mineral or rock type

Sandstone (River Cobble / Pebble)

Sedimentary Rock (Quartz Sandstone / Arenite)

Weathered sedimentary rock (likely sandstone)

Quartz-rich sandstone; exact identification requires a close-up or tests

Conglomerate (puddingstone)

Polymict conglomerate; rounded pebbles and cobbles cemented in a finer matrix

Jasper with Quartz

Silicon dioxide (SiO2)

Weathered sandstone

Quartz-rich clastic sandstone, chiefly SiO₂ with minor feldspar, lithic grains, and iron-oxide/clay cement

Fossilized Shell Fragment

Invertebrate marine fossil, likely calcium carbonate replacement

Fossil shell fragment

Likely a fossilized bivalve or brachiopod valve; exact identification requires the other valve, locality, and matrix

Iron-stained quartz fragment (probable quartzite or chert)

Quartz, SiO₂; possibly iron-oxide-stained microcrystalline silica

Weathered sedimentary rock, likely fine-grained sandstone or siltstone

Quartz-rich sandstone/siltstone; exact identification requires close examination

Small brown-gray rock fragment

Unidentified fine-grained rock; exact lithology cannot be determined from the image

Possible smooth beach pebble (identity uncertain)

Unidentified fine-grained siliceous pebble; possibly chert or quartzite