Rock (Likely Sedimentary)

Chert (varietal: Flint Pitted Pebble)

Cryptocrystalline Quartz (SiO2)

Sandstone (likely Graywacke or Arkose)

Arenite

Sandstone (likely Arkosic)

Arenite (SiO2 based)

Tumbled brown stone, possibly jasper or weathered chert

Uncertain; likely microcrystalline quartz (SiO₂), potentially iron-stained jasper/chert

Rounded quartz-rich pebble

Lithic pebble; likely quartz/quartzite with iron-oxide staining

Quartz-rich breccia or conglomerate

Siliciclastic conglomerate/breccia, predominantly quartz and feldspar clasts in a rusty iron-oxide cement

Weathered iron-rich rock, possibly hematite-bearing chert

Hematite (Fe₂O₃), likely mixed with silica and iron oxides

Rounded quartz-rich sandstone pebble

Quartz arenite or feldspathic sandstone; primarily SiO₂ quartz grains with minor feldspar, iron oxides, and clay minerals

Weathered iron-rich concretion or ironstone cobble

Goethite–hematite–limonite-rich ironstone; exact identification requires testing

Weathered chert or chalcedony nodule

Microcrystalline quartz (SiO₂), possibly silicified limestone or agate-like chalcedony

Likely weathered sandstone or iron-stained sedimentary fragment

Quartz-rich sandstone; exact identification requires testing

Tumbled brown mineral/rock specimen

Indeterminate from image; likely brown jasper, chert, or iron-stained quartzite

Fossiliferous Limestone

Calcite (CaCO3) Rich Bio-sedimentary Rock

Rounded river pebble

Lithic sandstone or fine-grained volcanic/metamorphic pebble; exact identity requires testing

Sandstone (Greywacke)

Arenite / Wacke (Mainly SiO2 with various lithic fragments)

Likely weathered gray limestone or shale fragment

Calcite-rich carbonate rock (limestone), possibly calcareous shale

Tumbled dark gray stone, possibly basalt or andesite

Fine-grained mafic to intermediate volcanic rock; exact mineralogy cannot be confirmed from the photograph

Sandstone (Weathered Cobble)

Clastic Sedimentary Rock (primarily SiO2)

Fossilized tooth, likely a mammalian tooth fragment

Indeterminate fossil tooth; possibly an ungulate or carnivoran tooth

Sandstone (Quartzose Sandstone)

Arenite (primarily SiO2)

Polished garnet-bearing metamorphic rock

Likely garnet mica schist or garnet-bearing gneiss; garnet is commonly almandine, Fe₃Al₂(SiO₄)₃

Quartz geode/druse specimens

Quartz, silicon dioxide (SiO₂), likely iron-stained drusy quartz in a vuggy host rock

Weathered sandstone or siltstone cobble

Clastic sedimentary rock, likely quartz–feldspar sandstone/siltstone

Sandstone Cobble with Iron Staining

Arenite with Limonite/Goethite coatings

Sandstone (likely Arkosic or Lithic Sandstone)

Arenite (SiO2 based with mineral inclusions)

Red Sandstone

Clastic sedimentary rock (Quartz arenite/Arkose)

Light-colored pebble, likely quartzite or weathered limestone

Indeterminate from image; possible quartzite (microcrystalline SiO₂)

Banded metamorphic rock, likely gneiss or amphibolite

Composition uncertain; probable quartz–feldspar–amphibole assemblage

Likely weathered gneiss or granite fragment

Quartz–feldspar–mica aggregate; probably granitoid gneiss, identification uncertain from the photograph

Iron-rich sandstone or laterite fragment

Ferruginous sandstone; possibly laterite/goethite-rich ironstone

Rounded river pebble

Probably quartz-rich sandstone or lithic sandstone; exact identification requires testing

Chert (River Pebble with Liesegang Rings)

Microcrystalline Silicon Dioxide (SiO2)

Weathered volcanic rock, likely basaltic andesite

Basaltic andesite (fine-grained plagioclase–pyroxene rock; provisional visual identification)

Biotite-rich gneiss (possibly mica schist)

Quartz–feldspar–biotite gneiss; mica-rich metamorphic rock

Iron-oxide-stained rock with a pale mineral vein

Likely limonite/goethite-stained quartz-bearing rock; exact identification is uncertain from the image

Banded gneiss (likely garnet-biotite or quartz-feldspar gneiss)

Gneiss; predominantly quartz (SiO₂), feldspar, and dark biotite/amphibole

Orange calcite (likely)

Calcite, calcium carbonate (CaCO₃)

Chert (and/or Siltstone River Pebble)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Banded gneiss pebble

Gneiss, commonly quartz–feldspar–biotite gneiss

Red jasper (likely tumbled or polished)

Jasper, an opaque microcrystalline variety of quartz (SiO₂), colored by iron oxides

Chert

Chert (SiO2)

Sandstone (likely Quartzose Sandstone)

Arenite (composed primarily of SiO2)