Biogenic Material

Quartzite

Quartzite

Likely quartz-rich rock or weathered granite fragment

Granite-like quartz–feldspar aggregate; exact identification requires testing

Red Sandstone

Arenite (with Iron Oxide cement)

Sandstone (Quartzose Sandstone)

Clastic sedimentary rock (primarily SiO2)

Fossilized Nut / Coprolite / Concretion

Trace Fossil / Permineralized Plant Material

Concrete with Aggregate

Artificial Conglomerate (Cement and Aggregate)

Unakite

Epidotized Granite

Tiffany Stone

Fluorite-bearing Opalized Breccia

Fossilized Shark Tooth

Selachimorpha fossil

Petrified Wood

Silicified Wood (primarily SiO2)

Blue-green turquoise (probable)

Turquoise — hydrated copper aluminum phosphate, CuAl₆(PO₄)₄(OH)₈·4H₂O

Serpentinite with carbonate veins and weathering rind

Serpentinite; chiefly serpentine-group minerals (antigorite, lizardite, chrysotile), with calcite/magnesite and accessory magnetite

Polished black-and-brown river pebble

Likely altered basalt or hornfels; exact identification requires testing

Likely serpentine-rich metamorphic rock

Serpentinite; chiefly serpentine-group minerals (antigorite, lizardite, or chrysotile), with possible magnetite and minor chlorite/talc

Polished fossiliferous limestone

Bioclastic limestone, chiefly calcite (CaCO₃)

Weathered iron-rich quartz or limonite-bearing stone

Quartz (SiO₂) with iron-oxide/hydroxide coatings, likely goethite–limonite

Serpentinite (likely)

Serpentinite, dominated by serpentine-group minerals (chrysotile, lizardite, or antigorite), commonly with magnetite and relict olivine/pyroxene

Greenstone / Serpentinite Pebble

Serpentinite (Hydrated Magnesium Silicate, Mg3Si2O5(OH)4)

Serpentinite (serpentine-rich rock)

Serpentinite; chiefly serpentine-group minerals, Mg₃Si₂O₅(OH)₄, with possible magnetite, chlorite, and talc

Schist

Mica schist, likely muscovite–biotite schist with quartz and feldspar

Concrete / Conglomerate (Man-made)

Artificial Conglomerate (Cementitious Composite)

Jasper

Silicon Dioxide (SiO2) with impurities

Asphalt Concrete (Bituminous Conglomerate)

Anthropogenic Bituminous Conglomerate

Petrified Wood

Silicified wood (Quartz/Chalcedony replacement of organic matter)

Petrified Wood

Silicified Wood (primarily SiO2)

Brown botryoidal chalcedony (likely iron-stained agate)

Microcrystalline quartz, SiO₂; chalcedony/agate variety

Mottled gabbro or diorite pebble

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

Zircon

Zirconium Silicate (ZrSiO₄)

Serpentinite

Serpentinite; chiefly serpentine-group minerals (lizardite, antigorite, chrysotile), often with magnetite and minor brucite

Greenstone or Metabasalt

Metabasalt / Chlorite Schist

Sandstone

Arenite (SiO2 primarily)

Jasper / Chert (tumbled/water-worn)

Microcrystalline Quartz (SiO2)

Agate

Cryptocrystalline quartz, Chalcedony (SiO2)

Sandstone

Arenite (SiO2 primarily)

Quartz Pebble

Silicon Dioxide (SiO2)

Sandstone Pebble

Sandstone (primarily Quartz, SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Red Sandstone or Brick Fragment

Arenite (if sandstone)

Tree Agate

Silicon dioxide (SiO2)

Asphalt (Road Aggregate)

Bituminous conglomerate

Limestone Gravel

Sedimentary Calcium Carbonate (CaCO3)