Synthetic Material (Not A Rock Or Mineral)

Gravelly, weathered sediment (likely glacial till)

Unconsolidated diamicton; mixed lithologies, commonly including quartz, feldspar, and weathered silicate rock fragments

Granite Cobble

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

Petrified Wood

Silicified Wood (SiO2)

Agate (specifically, multi-colored or pastel-dyed agate)

Silicon dioxide (SiO2) - specifically, a cryptocrystalline variety of quartz known as Chalcedony, with banding classified as Agate. (If it were Fluorite, the chemical formula would be Calcium Fluoride - CaF2).

Black Obsidian

Volcanic Glass (predominantly SiO2, Silicon Dioxide)

White quartz geode

Quartz, silicon dioxide (SiO₂), likely a druzy quartz geode

Chert (Arrowheads)

Microcrystalline Quartz (SiO2)

Conglomerate

Conglomerate (clastic sedimentary rock)

Tumbled carnelian agate with dark mineral inclusions

Carnelian, an orange variety of microcrystalline quartz (chalcedony), SiO₂; dark inclusions are likely iron oxides/hydroxides, possibly hematite, goethite, or a basaltic/matrix fragment

Crazy Lace Agate

Microcrystalline Quartz (SiO2)

Chert (Chalcedony/Agate)

Microcrystalline Quartz (SiO2)

Chert (White Chert)

Silicon Dioxide (SiO2)

Jasper

Microcrystalline Quartz (SiO2)

Basalt (River Pebble)

Aphanitic Mafic Igneous Rock

Mixed collection of natural stones

Several unidentified lithologies, likely including basalt, granite, quartzite, sandstone, and weathered metamorphic rocks

Weathered quartz-rich rock, likely sandstone or quartzite

Quartz arenite (sandstone) or quartzite; predominantly SiO₂

Banded River Cobble with Mafic Dike

Hydrothermally altered Graywacke or Sandstone with Mafic Intrusion

Granite

Granite

Polished/tumbled quartz-rich pebble, possibly jasper or quartzite

Indeterminate; likely microcrystalline quartz (SiO₂), potentially iron-stained jasper or quartzite

Rounded basalt cobble

Basalt (fine-grained mafic volcanic rock)

Quartzite Pebble

Quartzite (mostly SiO2)

Banded Gneiss

Gneiss

Pebble

Lithic fragment / Water-worn rock

River Stone (likely Quartzite or Sandstone)

Metamorphosed Quartz-rich Rock (SiO2)

Granite Pebble

Granite (High-silica plutonic rock)

Basalt River Stone

Aphanitic Mafic Volcanic Rock

Basalt Cobble

Aphanitic Mafic Volcanic Rock (Basalt)

Quartzite Pebble

Quartzite (SiO2)

Serpentinite

Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)2-3(Si, Al, Fe)2O5(OH)4

Chert / Flint

Silicon dioxide (SiO2)

Dacite

Dacite (intermediate volcanic rock high in silica)

Unakite

Epidotized Granite

Basalt pebble

Basalt

Granite

Granite (Phaneritic intrusive igneous rock)

Unakite (likely)

Epidote–pink feldspar–quartz rock; commonly termed unakite

Granite

Phaneritic Felsic Igneous Rock

Small vesicular volcanic rock, likely scoria

Scoria; predominantly basaltic to andesitic volcanic rock

Unidentified weathered rock, possibly quartz-bearing granite or rhyolite

Indeterminate; likely quartz–feldspar-rich silicate rock

Chert / Jasper

Microcrystalline Quartz (SiO2)

Iron-Stained Quartz (Red Quartz)

Silicon Dioxide (SiO2) with Hematite/Limonite inclusions

Chert (Flint)

Microcrystalline quartz (SiO2)

Agate

Agate (Cryptocrystalline Variety of Quartz, SiO2)