Unknown (Likely Sedimentary Or Metamorphic)

Quartz (Grain)

Silicon Dioxide (SiO2)

Weathered sandstone fragment

Quartz-rich sandstone (compositionally uncertain)

Tumbled quartz pebble, possibly citrine or pale smoky quartz

Quartz (SiO₂), likely microcrystalline/tumbled material

Gneiss

High-grade metamorphic rock (Gneiss)

Banded Gneiss

Gneiss (complex metamorphic silicate rock)

Pale quartz-rich stone, possibly calcite

Likely quartz (SiO₂) or calcite (CaCO₃); image resolution prevents confident separation

River Pebble (Gneiss or Quartzite variant)

Metamorphic rock specimen (likely Quartzite or Gneiss)

Argillite (with Barnacles)

Argillite (metamorphosed mudstone/shale)

Ferruginous Quartz

Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3) inclusions

Mica-rich schist

Muscovite–quartz schist (tentative; image alone cannot confirm mineral composition)

Banded metamorphic rock, likely gneiss or amphibolite

Composition uncertain; probable quartz–feldspar–amphibole assemblage

Rounded river cobbles, likely weathered sandstone/mudstone and quartz-rich rock

Uncertain from photograph; probable lithologies include quartz sandstone, siltstone/mudstone, and locally altered volcanic or metamorphic clasts

Banded gray stone, likely slate or fine-grained metamorphic rock

Probably slate or phyllite; composition commonly mica, quartz, and clay-derived minerals

Tumbled gneiss (likely biotite gneiss)

Gneiss; quartz–feldspar–biotite assemblage

Likely rough quartz with iron-oxide staining

Quartz (SiO₂), possibly with iron-oxide inclusions or surface staining

Weathered limestone or calcareous concretion

Calcite-rich limestone; predominantly calcium carbonate (CaCO₃)

Weathered sandstone or metasedimentary rock

Quartz-rich sandstone; possibly weakly metamorphosed quartzite

Likely tumbled quartz or chalcedony fragment

Quartz (SiO₂), possibly microcrystalline chalcedony

River Stones (Quartzite and Sandstone)

Quartzite / Sedimentary Rock (SiO2 dominant)

Rounded quartz-rich river pebbles

Alluvial gravel; commonly quartzite, chert, and quartz-bearing sandstone fragments

Likely foliated metamorphic rock (schist or phyllite)

Undetermined from the image; possibly mica-rich schist or phyllite

Quartz-rich metamorphic rock, likely mica schist or quartzite

Quartz (SiO₂) with mica, feldspar, and possibly iron-oxide staining

Red Jasper

Silicon Dioxide (SiO2) with iron oxide inclusions

Fossil-bearing fine-grained sedimentary rock

Likely fossiliferous mudstone or shale; visible feature may be a plant fragment, trace fossil, or mineral vein

Biotite-rich schist (likely mica schist)

Mica schist; predominantly quartz, biotite mica, and feldspar

Likely mica schist

Mica-rich schist, probably muscovite–biotite schist

Milky quartz

Quartz (silicon dioxide, SiO₂)

Mica-rich metamorphic rock, likely schist

Muscovite–biotite schist, possibly phyllite; composition dominated by mica and quartz

Banded gneiss (probable)

Quartz–feldspar–mica gneiss; composition commonly dominated by quartz, feldspar, and biotite/hornblende

Banded gneiss (likely weathered paragneiss)

Gneiss; quartz–feldspar–mica ± amphibole assemblage

Quartz-rich metamorphic rock, likely mica schist or quartzite

Quartz (SiO₂) with probable mica, feldspar, and dark accessory minerals

Coarse-grained metamorphic rock, likely gneiss

Biotite–quartz–feldspar gneiss (probable; exact identification requires a fresh surface and tests)

Rounded greenish pebble

Indeterminate; possibly altered basalt, greenstone, or fine-grained serpentinite

Quartz Pebble

Crystalline Silicon Dioxide (SiO2)

Small iron-stained quartz-rich rock fragment

Likely quartz (SiO₂) with iron-oxide staining; exact identification is uncertain from the image

Light-colored, weathered rock fragment

Undetermined; possibly weathered granite or granitic rock

Gneiss (Gneissic Granite)

Gneiss

Gneiss

Foliated Metamorphic Gneiss

Weathered quartz-rich rock, possibly quartzite or silicified sandstone

Quartzite (mostly SiO₂), with possible iron-oxide staining and minor feldspar/mica

Quartz (Gray/Smoky Varieties)

Silicon Dioxide (SiO2)

Small tumbled quartz-like pebble

Likely quartz (SiO₂), possibly iron-stained chalcedony or feldspar

Mica-rich schist (likely biotite schist)

Mica schist, composed mainly of biotite and/or muscovite with quartz and feldspar