Sedimentary Rock (Possibly A Conglomerate Or Coarse Grained Sandstone)

Likely granite or granitic gneiss

Granite: quartz + feldspar + mica; possibly foliated into gneiss

Conglomerate

Clast-supported polymictic conglomerate; rounded quartz and other rock fragments in a dark matrix

Weathered sandstone block

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

Possibly biotite-rich schist

Mica schist, composed mainly of quartz and mica (often biotite); exact identification is uncertain from the photo.

Rounded pebble (likely quartz-rich sandstone or weathered chert)

Indeterminate from image; possibly quartz (SiO₂)-rich lithic material

Garnet-bearing Schist / Conglomerate Specimen

Metamorphic rock with almandine garnet porphyroblasts

Weathered metamorphic rock, possibly schist or gneiss

Indeterminate; likely quartz–feldspar–mica rock, potentially greenschist or gneiss

Tumbled reddish-brown pebble

Indeterminate lithic fragment; possibly iron-stained quartzite, chert, or jasper

Weathered granite or granitic gneiss fragment

Quartz–feldspar–mica granite; possibly foliated granitic gneiss

Quartz Pebble

Silicon Dioxide (SiO2)

Quartz-rich gneiss (probable banded metamorphic rock)

Gneiss; composition chiefly quartz, feldspar, and mica, possibly with amphibole

Tumbled reddish-brown pebble, likely sandstone or iron-rich quartzite

Probable ferruginous sandstone (quartz-rich; SiO₂ with iron oxides), possibly quartzite

Banded metamorphic rock, likely gneiss

Biotite–quartz–feldspar gneiss, possibly amphibolite-bearing

Weathered limestone or calcareous sandstone

Calcite-rich carbonate rock, chiefly calcium carbonate (CaCO₃), possibly with quartz grains

Jasper Conglomerate (Puddingstone)

Siliceous Conglomerate (Quartz and Jasper clasts in a fine-grained matrix)

Puddingstone

Polymictic Conglomerate

Quartz-bearing polymictic conglomerate

Conglomerate with milky quartz clasts; composition may include quartzite and weathered feldspathic/mafic rock fragments

Gneiss

Gneiss (High-grade metamorphic rock)

Tumbled polymictic stone, likely jasper-bearing conglomerate

Siliciclastic conglomerate with microcrystalline quartz (jasper/chert) and altered volcanic or feldspathic clasts

Weathered limestone

Calcite-rich carbonate rock (mostly CaCO₃), possibly fossiliferous limestone

Mixed sandstone and iron-rich sedimentary rock fragments

Quartz arenite/subarkose, with ferruginous cement and possible iron-oxide staining

Limestone Breccia

Sedimentary Breccia (Calcareous)

Weathered quartz-rich rock, possibly quartzite or iron-stained quartz

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

Sandstone with Lichen and Iron Oxide Staining

Quartz Arenite / Sandstone

Weathered sandstone or altered volcanic rock

Indeterminate; likely quartz–feldspar-rich sandstone, possibly tuff

Weathered gray pebble, likely quartzite or chert

Quartzite (microcrystalline SiO₂); possibly chert (cryptocrystalline SiO₂)

Sedimentary Breccia

Clastic Breccia (CaCO3/SiO2 matrix)

Quartz-rich sandstone or quartzite

Quartz (SiO₂)-rich clastic rock; possibly weakly metamorphosed quartzite

Weathered gray metamorphic rock, likely schist or gneiss

Micaceous quartz-feldspar schist/gneiss; exact identification requires a fresh surface and testing

Banded Gneiss River Pebble

Gneiss

Conglomeratic gravel / polymictic breccia

Polymictic rudite, likely anthropogenic or beach/stream gravel; composition varies

Dark igneous rock, possibly basalt or gabbro

Basalt–gabbroic rock; chiefly plagioclase feldspar and pyroxene, with possible olivine or iron oxides

Gneiss pebble

Biotite–quartz–feldspar gneiss, possibly granitic gneiss

Gneiss

Gneiss (Foliated Metamorphic Rock)

Iron-stained quartz-rich rock, likely sandstone or quartzite

Quartzite (SiO₂), possibly ferruginous sandstone

Polished orbicular granite (likely orbicular diorite)

Orbicular granitoid; chiefly quartz, feldspar, and dark amphibole/biotite

Weathered quartz-rich granitoid (likely granite or granodiorite)

Granite–granodiorite; chiefly quartz (SiO₂), feldspar, and minor mica/amphibole

Tumbled granite or granitic gneiss

Granite: quartz, feldspar, and mica; possibly foliated gneiss

Sandstone

Arenite (predominantly SiO2 quartz grains)

Weathered stone, likely sandstone or altered volcanic rock

Indeterminate; possibly quartz-rich sandstone or weathered tuff

Light-gray weathered stone, likely limestone

Calcite-rich limestone (CaCO₃), possibly calcareous sandstone or concrete-like rock

Weathered quartz-rich rock, possibly quartzite or silicified sandstone

Quartz-dominant aggregate; likely microcrystalline quartz (SiO₂), but exact identification requires testing