Organic Material (Likely A Fruit Or Berry)

Weathered sandstone or quartz-rich sedimentary pebble

Indeterminate lithic fragment; likely quartz arenite (sandstone)

Limestone

Calcareous sedimentary rock (CaCO3)

Weathered quartz-rich pebble (probable quartzite or quartz vein fragment)

Quartzite, predominantly silicon dioxide (SiO₂); exact identification is uncertain from the photograph

Sandstone (Ferruginous)

Arenite (Fe2O3 enriched)

Petrified Wood

Silicified wood (primarily Quartz/Chalcedony, SiO2)

Petrified Wood

Silicified Wood (SiO2)

Chert (Flint)

Microcrystalline silica (SiO2)

Sandstone (Quartz-rich)

Clastic sedimentary rock (SiO2 primary)

Banded Chert

Microcrystalline Quartz (SiO2)

Gravelly, weathered sediment (likely glacial till)

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

Jasper / Chert (River Pebble)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Chert (includes Flint & Jasper)

Chert (Siliceous sedimentary rock, chemical formula SiO2)

Iron-rich quartzite or limonite-bearing rock

Quartzite (SiO₂) with iron oxides/hydroxides, chiefly hematite and goethite

Likely tumbled jasper or chert specimens

Microcrystalline quartz (SiO₂), commonly jasper/chert; exact identification is uncertain from the photograph

Rounded brown pebble, likely quartz-rich sandstone or weathered quartzite

Indeterminate; probable quartz (SiO₂)-rich sandstone/quartzite with iron-oxide staining

Moss-covered Rock Fragment

Weathered Rock Fragment with Epilithic Growth

Petrified Wood

Silicified Wood (SiO2)

Petrified Wood (Black / Carbonized)

Silicon Dioxide (Quartz/Chalcedony replacing Organic Matter)

Chert

Microcrystalline Quartz (SiO2)

Sandstone

Arenite

Limestone

Calcium carbonate (CaCO3)

Limestone

Calcium Carbonate (CaCO3)

Quartzite

Quartzite (chiefly SiO2)

Petrified Wood

Silicified Wood (primarily SiO2)

Weathered limestone or calcareous concretion

Calcite-rich carbonate rock; primarily calcium carbonate (CaCO₃), commonly calcite

Petrified Wood

Silicified wood (Quartz, SiO2)

Rounded quartz-rich pebble

Likely milky quartz or quartzite (SiO₂)

Chert (Flint)

Silicon Dioxide (SiO2)

Ironstone Concretion (Boxwork)

Siderite-Limonite Concretion (FeO(OH)·nH2O)

Quartz geode

Microcrystalline quartz and drusy quartz (SiO₂), commonly lining a chalcedony-rich cavity

Iron-rich sandstone or laterite

Ferruginous sandstone; mainly quartz (SiO₂) cemented or stained by iron oxides such as hematite (Fe₂O₃) and goethite (FeO(OH))

Sandstone

Arenite (primarily SiO2)

Chert (with Quartz Vein)

Chert (Siliceous sedimentary rock, predominantly Microcrystalline Quartz SiO2)

Biotite-bearing granite or granitic gneiss

Quartz–feldspar–mica rock; chiefly quartz (SiO₂), feldspars, and biotite mica

Limestone

Calcium Carbonate (CaCO3)

Petrified Wood

Silicified Wood (primarily Quartz / Chalcedony: SiO2)

Chert / Jasper

Silicon Dioxide (SiO2)

Amber / Copal

Succinite (fossilized resin)

Chert (Jasper)

Microcrystalline Quartz (SiO2)

Milky quartz (likely)

Quartz, silicon dioxide (SiO₂)

Sandstone (likely Quartzose)

Arenite (primarily SiO2)

Quartz-bearing granite or granitic gneiss cobble

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