Sedimentary Or Igneous Fragment

Calcite

Calcite (calcium carbonate, CaCO₃), likely a massive crystalline specimen

Quartz (Small Grains)

Silicon Dioxide (SiO2)

Breccia

Sedimentary Breccia

Basalt Pebble and Shale Fragment

Extrusive volcanic rock and fine-grained sedimentary rock

Tumbled translucent quartz or chalcedony fragment

Silicon dioxide, SiO₂; likely quartz/chalcedony

Sandstone fragment

Arenite (primarily Quartz, SiO2)

Chert (likely flint)

Microcrystalline quartz (SiO₂), a variety of chert

Milky quartz

Quartz (silicon dioxide, SiO₂)

Quartz (Clear/White)

Silicon Dioxide (SiO2)

Small gray rock fragment, possibly limestone or marl

Undetermined carbonate-rich sedimentary rock; composition cannot be confirmed visually

Possible weathered sandstone or iron-rich sedimentary rock

Indeterminate siliciclastic rock; likely quartz-rich sandstone with iron-oxide cement

Pebble

Lithified rock fragment / Sedimentary clast

Metallic sulfide mineral specimen, likely pyrite-bearing ore

Likely pyrite (FeS₂), possibly mixed with other sulfides or host rock

Milky Quartz

Quartz (SiO2)

Polygenetic Conglomerate (or Breccia)

Clastic Sedimentary Rock

Weathered vesicular basalt (probable volcanic bomb)

Basalt, primarily plagioclase feldspar, pyroxene, and olivine

Quartz Pebble

Silicon Dioxide (SiO2)

Likely iron-stained quartz or quartzite fragment

Quartz (SiO₂), possibly ferruginous quartzite; identification is uncertain from the image

Quartz Crystal Fragment

Silicon Dioxide (SiO2)

Fossilized coral or stromatoporoid fragment

Tabulate coral (e.g., Favosites) or stromatoporoid; exact identification requires microscopy

Coquina or Fossiliferous Sandstone

Fossiliferous Calcarenite (CaCO3 with SiO2 inclusions)

Likely weathered quartz-rich rock fragment

Indeterminate; possibly quartz-bearing sandstone or chert with iron-oxide staining

Small pale stone, likely quartzite or limestone fragment

Indeterminate; possible quartzite (mostly SiO₂) or calcitic limestone (CaCO₃)

Weathered quartz-rich stone, possibly chalcedony or calcite

Likely microcrystalline quartz (SiO₂) or calcite (CaCO₃); exact identification requires testing

Likely weathered quartz-rich stone

Probably quartz-bearing sandstone or milky quartz; exact identification requires testing

River Rock

Sedimentary clast

Small feldspar-rich rock fragment, possibly granite or pegmatite

Likely quartz–feldspar aggregate; exact identification is uncertain from the small, pale fragment

Weathered rock fragment

Unidentified, likely fine-grained mafic volcanic rock

Granite (small weathered fragment)

Granite, chiefly quartz, feldspar, and mica

Granite (probable)

Granite, a coarse-grained rock composed mainly of quartz, feldspar, and mica

Weathered rock fragment

Undetermined; possibly a coarse-grained granitoid

Likely granite fragment

Granite, a coarse-grained rock composed mainly of quartz, feldspar, and mica

Weathered light-colored rock fragment, possibly quartz-rich rock

Undetermined; appearance may be quartzite or a quartz-rich granite fragment

Iron-stained quartz-rich rock (likely weathered granite or quartzite)

Quartz–feldspar rock with iron-oxide staining; exact rock type cannot be confirmed from the image

Weathered volcanic rock (likely vesicular basalt)

Basalt, a fine-grained mafic volcanic rock; exact identification is uncertain from the image

Quartz-rich rock fragment

Likely granitic or granodioritic rock, composed chiefly of quartz and feldspar with possible mica

Small quartz-rich rock fragment (possibly weathered quartz vein material)

Quartz (SiO₂) in an undetermined host rock; the image is insufficient to identify the host confidently

Light-colored, weathered rock fragment

Unidentified felsic rock; possibly weathered granite or feldspar-rich rhyolite

Weathered, iron-stained rock fragment

Unidentified silicate-rich rock; the image is insufficient for a reliable species identification

Small weathered rock fragment, possibly quartz-rich

Unidentified lithic fragment; species cannot be determined from the image

Coquina or Fossilized Shell Fragment

Calcium Carbonate (CaCO3) / Biogenic Limestone

Weathered limestone or calcareous tufa

Calcite-rich carbonate rock, primarily CaCO₃ (often micritic limestone or travertine/tufa)