Rock (Likely Sedimentary)

Likely graphite-rich schist (graphitic schist)

Graphitic schist; chiefly quartz, mica, and graphite (carbon), with possible pyrite or feldspar

Mottled gabbro or diorite pebble

Coarse-grained mafic/intermediate intrusive rock; chiefly plagioclase feldspar plus pyroxene, with possible amphibole or biotite

Graphite-bearing schist (probable)

Graphite–quartz–mica schist; chiefly graphite (C), quartz (SiO₂), and mica

Pumice

Vesicular volcanic glass (Amorphous silica mixed with various oxides)

Milky Quartz with Iron Staining

Quartz (Silicon Dioxide) - SiO2

Dalmatian Jasper / Dalmatian Stone

Peralkaline Rock (Silicon Dioxide with Amphibole inclusions)

Tumbled cream chalcedony or quartz

Microcrystalline quartz, SiO₂; possibly iron-stained chalcedony

Rounded basalt cobble

Basalt (fine-grained mafic volcanic rock)

Riverstone Quartzite (Water-worn Siltstone/Quartzite)

Metamorphosed Quartz-rich Arenite (SiO2)

River Stone (likely Basalt or Chert)

Silicon Dioxide (SiO2) for chert or Mafic Extrusive Rock for basalt

River Rock (likely Quartzite or Chert)

Quartzite (primarily SiO2)

Quartz-bearing granite or granitic gneiss cobble

Granite; primarily quartz (SiO₂), feldspar, and mica/amphibole

Chert (Common Variety)

Cryptocrystalline Quartz (SiO2)

Red Sandstone

Arenite (primarily quartz with iron oxide cement)

Granite Pebble

Granite (Felsic intrusive igneous rock)

Pink Granite River Pebble

Phaneritic Felsic Igneous Rock (Granite)

Basalt

Basalt (Mafic Extrusive Igneous Rock)

Granite

Granite (phaneritic felsic intrusive rock)

Granite Pebble

Granite (Felsic Intrusive Igneous Rock)

Fossil Coral

Rugose Coral or Tabulate Coral (Phylum Cnidaria)

Granite

Phaneritic plutonic rock (SiO2 range 65-75%)

Granitoid (Granite/Granodiorite)

Plutonic igneous rock (variable composition, primarily SiO2)

Garnet-bearing metamorphic rock, possibly garnet amphibolite or mica schist

Almandine garnet (Fe₃Al₂Si₃O₁₂) in a mafic, amphibole–feldspar-rich matrix

Quartz geode (likely druzy quartz)

Quartz, silicon dioxide (SiO₂)

Rounded basalt cobble (probable)

Basalt; fine-grained mafic volcanic rock, chiefly plagioclase and pyroxene

Iron-stained quartz vein rock

Milky quartz (SiO₂) with limonite/goethite iron oxides, possibly in altered host rock

Quartz-bearing altered rock, possibly iron-stained quartz vein

Quartz (SiO₂) in a feldspathic/sericitized host, with iron-oxide staining

Quartz (specifically Clear Quartz with iron/hematite staining)

Silicon Dioxide (SiO2)

Quartzite with Hematite

Metamorphosed Quartz Sandstone (SiO2 with Fe2O3 inclusions)

Mica Schist with Iron Staining

Muscovite/Biotite Schist

Fluorite in Matrix

Fluorite (CaF2) within a host rock matrix

Jasper

Jasper (Silicon Dioxide, SiO2)

Chert (Jasper/Flint variety)

Silicon Dioxide (SiO2)

Banded Chert (Jasper)

Silicon Dioxide (SiO2)

Banded Sedimentary Rock

Sedimentary rock with Liesegang banding

Basalt with Epidote/Chlorite

Amygdaloidal Basalt (SiO2 with (Ca2(Al2,Fe)(SiO4)(Si2O7)O(OH)))

Granite Pebble

Felsic Plutonic Rock (primarily Quartz, Feldspar, and Mica)

Geode (Unopened)

Silicon dioxide with various inclusions (SiO2)

Weathered granite or granitic rock fragment

Granite; chiefly quartz, feldspar, and mica (composition uncertain from image)

Weathered porphyritic volcanic rock

Likely andesite or dacite, with feldspar phenocrysts in a fine-grained groundmass

River Cobble (likely Basalt or Mafic Igneous Rock)

Extrusive Mafic Igneous Rock (e.g., Basalt)

Granite

Granite