Sedimentary Or Igneous Fragment

Likely weathered gray stone or chert fragment

Uncertain; possibly microcrystalline quartz (SiO₂)-rich chert

Basalt and weathered granite-like rock

Dark specimen: basalt, likely vesicular or fine-grained mafic volcanic rock; tan specimen: uncertain, possibly weathered granite or iron-stained felsic rock

Quartz Pebble

Silicon Dioxide (SiO2)

Fossilized Tooth Fragment

Vertebrate Fossil (Mammalia indet.)

Orange chalcedony (likely carnelian), polished shard

Microcrystalline quartz, SiO₂; chalcedony variety, orange iron-oxide coloration

Quartz

Silicon Dioxide (SiO2)

Oolitic Ironstone

Sedimentary Ooidal Ironstone (Limonite/Hematite mixture)

Limestone with Fossil Inclusion

Calcium Carbonate (CaCO3)

Weathered chert or silicified limestone nodule

Microcrystalline quartz (SiO₂), possibly replacing limestone; exact identification requires testing

Chert (containing a small fossil)

Microcrystalline Quartz (SiO2)

Basalt

Basalt (Aphanitic Mafic Igneous Rock)

Sandstone (Quartzite-leaning)

Arenite (primarily SiO2)

Small seashell fossil or shell fragment

Likely calcium-carbonate shell material, chiefly aragonite or calcite; exact species indeterminate

Quartz (Small Grains)

Silicon Dioxide (SiO2)

Red Jasper (Opaque Chalcedony)

Silicon Dioxide (SiO2) with Hematite (Fe2O3) inclusions

Rough Citrine Quartz

Citrine (Silicon Dioxide, SiO2 with iron impurities)

Chert (specifically Pink/Tan Chert)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Flint or chert

Microcrystalline quartz (SiO₂), commonly called flint when dark and nodular

Tumbled, weathered limestone or calcareous concretion

Calcite-rich limestone; predominantly calcium carbonate (CaCO₃)

Greywacke with Quartz Vein

Greywacke (immature sandstone) with SiO2 inclusions

Fossiliferous Limestone / Fossil Fragment

Calcium Carbonate Matrix with Biogenic Inclusions (CaCO3)

Granitic Sand

Detrital sediment (predominantly Quartz, Feldspar, and Mica)

Quartz (Clear/White)

Silicon Dioxide (SiO2)

Milky quartz (likely quartz fragment)

Quartz, silicon dioxide (SiO₂)

Unidentified River Rock or Mudstone

N/A (Generic rock fragment)

Black basalt (likely polished or cut fragment)

Basalt; fine-grained mafic volcanic rock composed mainly of plagioclase, clinopyroxene, and often olivine or magnetite

Granite countertop with a small pale mineral fragment

Granite; predominantly quartz, feldspar, and mica

Milky quartz

Quartz (silicon dioxide, SiO₂)

Milky Quartz

Quartz (SiO2)

Milky quartz (likely quartz vein fragment)

Quartz, silicon dioxide (SiO₂)

Polygenetic Conglomerate (or Breccia)

Clastic Sedimentary Rock

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Generic Pebble / Rock Fragment

Lithic fragment / Weathered rock pebble

Pebble

Lithic fragment / Water-worn rock

River Pebble

Lithified rock fragment (variable composition)

Generic Pebble / Small Rock Fragment

Lithic fragment / Weathered rock particle

Pebble

Clast (Lithic fragment / Quartzite pebble)

Likely weathered granite or granitic gneiss fragment

Quartz–feldspar–biotite aggregate; possibly foliated granitic gneiss

Milky quartz with iron-oxide staining

Quartz, silicon dioxide (SiO₂), likely massive or coarsely crystalline; brown areas are limonite/goethite staining

Granite or granitic rock fragment

Felsic intrusive igneous rock, typically quartz + feldspar + mica; exact species uncertain from the image

Clear quartz (likely quartz crystal fragment)

Quartz, silicon dioxide (SiO₂)

Iron-rich flint or chert fragment

Microcrystalline quartz (SiO₂), likely ferruginous chert