Sedimentary Or Igneous Fragment

Tumbled or naturally broken quartz crystal

Quartz (silicon dioxide, SiO₂)

Weathered chert or silicified limestone nodule

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

Banded metamorphic river cobble, likely gneiss or metasedimentary rock

Quartz–feldspar–mica gneiss or quartzite with cross-cutting quartz veins

Likely weathered granite or granitic gneiss fragments

Granite: quartz–feldspar–mica aggregate; possibly biotite granite or weakly foliated gneiss

Quartz-rich pegmatite (possibly tourmaline-bearing)

Granitic pegmatite; chiefly quartz (SiO₂), feldspar, and dark mica/amphibole

Quartz–mica metamorphic rock, likely schist

Quartz–muscovite/biotite schist; predominantly SiO₂ quartz with phyllosilicate micas

Granitic Sand

Detrital sediment (predominantly Quartz, Feldspar, and Mica)

Brown chert (likely flint)

Microcrystalline quartz (SiO₂), chiefly chalcedony

Mixed small mineral specimens, likely quartz varieties

Uncertain from the image; translucent pieces may be quartz (SiO₂), while golden-brown pieces could be iron-stained quartz or calcite

Amethyst

Amethyst (SiO2 - Silicon Dioxide with iron impurities)

Likely quartz-rich rock fragment

Quartz (SiO₂), possibly iron-stained or included in a mixed rock; exact identification is uncertain from the image

Milky quartz fragment

Quartz (SiO₂)

Likely milky quartz fragment

Quartz (silicon dioxide, SiO₂)

Fossiliferous limestone

Bioclastic limestone, primarily calcite (CaCO₃), containing marine shell or coral fossils

Weathered sandstone block

Quartz-rich sandstone; exact composition cannot be confirmed from the image

Small pale stone, possibly quartz or limestone

Indeterminate from image; likely quartz (SiO₂) or calcite-rich limestone (CaCO₃)

Weathered quartz-rich rock, possibly granite or quartzite

Indeterminate; likely quartz–feldspar aggregate, potentially altered granite

Conglomerate (rounded-pebble rock)

Lithified polymictic conglomerate; clasts cemented by a finer mineral matrix

Pyrite

Iron Disulfide (FeS2)

Banded Agate / Shell Fossil Fragment

Silicon Dioxide (SiO2) / Calcium Carbonate (CaCO3)

Gneiss

Gneiss (High-grade Metamorphic Rock)

Likely pink feldspar-rich granite or pegmatite fragment

Uncertain from the image; possibly potassium feldspar (orthoclase/microcline) with quartz

Quartz-bearing rock fragment

Likely milky quartz with iron-oxide staining and possible host-rock minerals; exact identification is uncertain from the image.

Small dark stone (unidentified)

Undetermined; image lacks enough detail for reliable identification

Dark gray rock fragment (unidentified)

Undetermined; the image does not show enough detail for reliable identification

Likely quartz-rich rock fragment

Quartz (SiO₂), possibly iron-stained or mixed with feldspar

Chert (Flint)

Cryptocrystalline Quartz (SiO2)

Possible iron-rich pebble with a weathered inclusion

Unidentified; image alone does not support a reliable mineral or rock identification

White tumbled stone, likely quartz or calcite

Indeterminate; possibly quartz (SiO₂) or calcite (CaCO₃)

Weathered rock fragment (likely limestone)

Calcite-rich limestone, composition and identity uncertain from the image

Brown chert (likely flint)

Microcrystalline quartz (SiO₂), variety chert; identification from the image is approximate

Likely flint (chert) fragment

Chert, microcrystalline quartz (SiO₂)

Concrete fragment or Conglomerate

Artificial Conglomerate (Concrete) or Natural Conglomerate

Weathered igneous rock fragment, possibly granite or granitic gneiss

Indeterminate; likely quartz–feldspar–mica aggregate (granite), possibly foliated gneiss

Pyrite

Iron Disulfide (FeS2)

River Pebble

Polished Rock Fragment

Unidentifiable embedded dark fragment

Indeterminate; possibly a dark silicate mineral or lithic inclusion

Quartz Pebble

Silicon Dioxide (SiO2)

Milky quartz pebble

Quartz (silicon dioxide, SiO₂)

Raw quartz-bearing mineral fragment

Quartz, silicon dioxide (SiO₂), possibly included or matrix-bearing

Milky quartz (rough quartz fragment)

Quartz, silicon dioxide (SiO₂)

Conglomerate

Sedimentary Conglomerate