Rock (Likely Sedimentary)

Dark gray weathered pebble, likely basalt

Basalt; chiefly plagioclase feldspar, pyroxene, and commonly olivine or iron oxides

Limestone (Flagstone)

Fossiliferous Limestone (CaCO3)

Mosasaur Tooth Fossil

Mosasauridae (likely Prognathodon or Plioplatecarpus)

Rhyolite (likely porphyritic)

Rhyolite; chiefly quartz, alkali feldspar, plagioclase, and volcanic glass, with possible iron-oxide staining

Quartz-bearing conglomeratic rock with orange feldspar/calcite inclusion

Probably porphyritic granite or granitic pegmatite; exact identification requires a thin section or tests

Quartzite Cobble

Quartzite (SiO2)

Chert / River Jasper

Silicon Dioxide (SiO2)

Chert (Jasper/Pebble)

Microcrystalline Quartz (SiO2)

Quartz Geode

Crystalline Silicon Dioxide (SiO2) in sedimentary matrix

Sedimentary River Rock

Siliciclastic Sedimentary Rock (Quartzite or Sandstone pebble)

Brecciated Jasper

Silicon Dioxide (SiO2) with varying mineral inclusions (Iron Oxide, Hematite, Clay)

Fossilized Bivalve in Limestone

Class Bivalvia within Sedimentary Matrix (likely CaCO3)

Pink Granite

Granite (Phaneritic igneous rock rich in Alkali Feldspar and Quartz)

Sandstone (with Rock Art)

Sandstone (Clastic Sedimentary Rock)

Sandstone

Arenite (SiO2 dominant)

Quartz (River Pebble)

Silicon Dioxide (SiO2)

Granite with Mafic Inclusions

Granite (Phaneritic igneous rock composed of Quartz, Feldspar, and Mica)

Granite

Granite (composed primarily of Quartz, Feldspar, and Mica)

Porphyritic Basalt or Diabase

Porphyritic Igneous Rock

Limestone River Pebble

Sedimentary Calcium Carbonate (CaCO3)

Polished white chalcedony or milky quartz pebble

Chalcedony, microcrystalline quartz (SiO₂), possibly with iron-oxide staining or a minor mineral inclusion

Sandstone and Conglomerate pebbles

Sedimentary clastic rock

Shale or Mudstone

Argillaceous sedimentary rock

Gneiss

Feldspathic biotite gneiss; a high-grade metamorphic rock composed mainly of quartz, feldspar, and mica

Sandstone (Quartzose Sandstone)

Arenite (primarily SiO2)

Dark gray igneous rock, likely basalt

Basalt; fine-grained plagioclase–pyroxene rock, commonly with minor olivine and magnetite

Tumbled dark igneous rock, likely basalt

Basalt; commonly composed of plagioclase feldspar, pyroxene, and olivine

Pink-and-white quartz-rich rock, likely rose quartz or quartzite

Quartz (SiO₂), possibly rose-quartz-bearing quartzite; minor iron-oxide staining

Conglomerate Pebble (with Chert / Quartz)

Sedimentary Conglomerate / Breccia Pebble

Quartz-rich rock fragment

Microcrystalline quartz (SiO₂), possibly chalcedony or quartz-bearing breccia

Lava Rock with Fabric Impression

Scoria or Basalt with anthropogenic impressions

Chert (Iron-stained)

Microcrystalline silica (SiO2) with trace Iron oxide (Fe2O3)

Chert / Fossiliferous Limestone

Sedimentary Chert (often containing CaCO3 or SiO2 replacements)

Rounded granite pebble

Granite; chiefly quartz, feldspar, and mica

Porphyritic Basalt

Amygdaloidal Porphyritic Basalt

Mixed polished gemstone bead lot, likely dyed agate and quartz

Chalcedony (microcrystalline quartz, SiO₂), with possible amethyst, aventurine, and other dyed quartz varieties

Banded Iron Formation (BIF)

Banded Iron Formation

Possible weathered mica-rich metamorphic fragment

Mica schist or phyllite (quartz–mica assemblage; identification uncertain from image)

Porphyry

Porphyritic Igneous Rock (likely Porphyritic Andesite or Basalt)

River Cobble (likely Metasedimentary or Basalt)

Metamorphosed Siltstone or Altered Fine-grained Igneous Rock

Siltstone with Sandstone Bands

Siltstone (composed of Quartz and Clay minerals)

Likely weathered sandstone or iron-rich chert fragment

Indeterminate; probable quartz-rich sandstone (SiO₂) with iron-oxide cement, possibly chert