Sedimentary Or Igneous Fragment

Quartz (Milky or Cloudy)

Silicon Dioxide (SiO2)

Likely weathered igneous rock fragments

Indeterminate; possibly basaltic or granitic rock with quartz, feldspar, and dark mafic minerals

Quartz (with inclusions / Sandstone fragment)

Silicon Dioxide (SiO2)

Chert or microcrystalline quartz fragment

Chert; cryptocrystalline SiO₂, possibly chalcedony-rich

Limestone with Fossil

Sedimentary limestone, calcium carbonate (CaCO3)

Fossilized Shell Fragment

Bivalvia or Gastropoda (Class) fragment

Pink granite fragment

Granite, chiefly quartz, alkali feldspar, plagioclase, and minor biotite/hornblende

Likely weathered granite or granitic pegmatite fragment

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

Quartz Crystal Fragment

Silicon Dioxide (SiO2)

Likely weathered chert or siliceous limestone fragment

Microcrystalline quartz (SiO₂), possibly with calcite (CaCO₃)

Red Sandstone or Brick Fragment

Arenite (if sandstone)

Coquina

Biogenic Limestone (Coquina)

Amethyst Geode Fragment

Quartz (SiO2) with trace iron impurities

Quartz crystal fragment

Quartz (silicon dioxide, SiO₂)

Likely weathered limestone or marble fragment

Calcite-rich carbonate rock; likely limestone (CaCO₃), possibly recrystallized marble

Pea Gravel / River Gravel

Unconsolidated Clastic Sedimentary Aggregate

Pebble (likely Limestone or Siltstone)

Lithic fragment (calcareous or siliciclastic)

River Pebble

Quartzo-feldspathic rock fragment

Weathered quartz-rich pebble

Likely quartzite or quartz-bearing granitoid; exact identification requires testing

Weathered quartz-rich pebble

Likely granitic or feldspathic clast; chiefly quartz (SiO₂) and feldspar

Fossiliferous Limestone

Biogenic Limestone (Calcium Carbonate, CaCO3)

Likely weathered quartz-rich stone

Indeterminate; possibly quartz-bearing granite or milky quartz

Milky quartz (quartz-rich rock fragment)

Quartz, silicon dioxide (SiO₂)

Small metallic mineral fragment

Unidentified metallic sulfide or native-metal fragment

Weathered iron-rich rock fragment

Likely limonite/goethite-bearing rock, possibly altered pyrite or mica schist

Fossilized Bone Chunk

Permineralized Vertebrate Bone (indeterminant)

Weathered granite or granitic pegmatite fragment

Felsic intrusive rock composed mainly of quartz, feldspar, and minor mica

Weathered quartz-rich pebble

Milky quartz, likely with iron-oxide staining; exact rock type uncertain from image

Blue-gray quartz-rich pebble, possibly granite or granodiorite

Quartz–feldspar–mica aggregate; likely granodiorite (exact identification requires testing)

Small quartz-rich rock fragment

Likely quartz (SiO₂), possibly a pale granite or feldspar-bearing fragment

Sandstone (likely Greywacke or Siltstone variety)

Arenite / Siltstone (primarily SiO2)

Raw quartz crystal fragment

Quartz (silicon dioxide, SiO₂), likely iron-stained or included quartz

Small transparent crystal fragment, possibly quartz

Quartz (SiO₂), tentative identification

Black tourmaline (likely schorl)

Schorl, NaFe3Al6(BO3)3Si6O18(OH)4

Likely weathered quartz or quartz-rich pebble

Quartz, silicon dioxide (SiO₂)

Possible weathered quartz-rich rock or iron-stained mineral fragment

Indeterminate; possibly quartz (SiO₂) with iron-oxide inclusions

Weathered iron-rich river pebble

Ferruginous sandstone or ironstone; composition likely quartz with iron oxides (hematite/goethite)

Chert (Arrowhead Preform)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Ironstone Concretion

Siderite or Goethite Concretion

Carved limestone architectural fragment

Limestone, predominantly calcite (CaCO₃), possibly weathered fossiliferous or oolitic limestone

Milky quartz fragment

Quartz, silicon dioxide (SiO₂)

Obsidian (likely black volcanic glass)

Obsidian; naturally occurring rhyolitic glass, primarily SiO₂