Sedimentary Or Igneous Fragment

Reddish-brown rock fragment, possibly iron-stained sandstone

Unidentified iron-oxide-stained rock; sandstone is a tentative visual identification

Weathered gray stone fragment

Undetermined; possibly limestone or sandstone

Chalcedony Geode Fragment

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Sandstone (Ferruginous)

Arenite with Iron Oxide cement

Chert (Jasper/Flint variety)

Microcrystalline Quartz (SiO2)

Moss-covered Rock Fragment

Weathered Rock Fragment with Epilithic Growth

Granite fragment

Granite (Felsic intrusive igneous rock)

Weathered quartz-rich rock fragment

Likely granitic or pegmatitic fragment; chiefly quartz (SiO₂) with feldspar and iron-oxide staining

Weathered granite or granitic gneiss

Granite; chiefly quartz, feldspar, and mica

Weathered granite or granitic rock

Granite; chiefly quartz, feldspar, and mica, with possible iron-oxide staining

Weathered quartz-rich rock, possibly granite or quartzite

Likely quartz–feldspar aggregate; precise identification requires testing

Weathered feldspar-rich granite fragment

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

Weathered granite or granitic pegmatite fragment

Granite; chiefly quartz (SiO₂), feldspar, and minor biotite/hornblende

Granite fragment

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

Granite fragment

Granite, composed mainly of quartz, potassium feldspar, plagioclase, and mica

Tumbled dark pebble, likely hematite or magnetite

Hematite (Fe₂O₃) or magnetite (Fe₃O₄); identification is uncertain from the image alone

Weathered quartz-rich rock fragment

Likely quartz-bearing feldspathic fragment; exact identification requires testing

Likely quartz-rich rock fragment

Indeterminate; probably microcrystalline quartz (SiO₂) with minor feldspar or weathering minerals

Small brown mineral fragment, possibly quartz/chert

Uncertain; likely microcrystalline quartz (SiO₂) or a weathered silicate rock

Milky Quartz

Silicon Dioxide (SiO2)

Orthoclase Feldspar

Orthoclase (KAlSi3O8)

Quartz-rich rock fragment (tentative)

Quartz, silicon dioxide (SiO₂), possibly in a weathered host rock

Small reddish-brown mineral fragment, likely quartz-bearing rock

Indeterminate; possibly iron-stained quartz or feldspar-rich stone

Likely weathered quartz-rich pebble

Uncertain; possibly granite or quartz-bearing volcanic rock

Uncertain green-brown mineral fragment

Possibly epidote, chlorite, or altered amphibole; exact identification requires testing

Tumbled pink feldspar pebble

Potassium feldspar, commonly microcline or orthoclase (KAlSi₃O₈)

Quartz-rich metallic-looking pebble

Likely quartz or quartzite; exact identification is uncertain from the blurred image

Gold-bearing dark rock, possibly magnetite with iron-oxide staining

Likely magnetite (Fe₃O₄) with limonite/goethite; metallic patches may be gold or weathered sulfide, unconfirmed

Iron-stained quartz-rich cobble, possibly weathered granite or quartz vein rock

Quartz–feldspar aggregate with iron-oxide staining; exact classification is uncertain from the photograph

Quartz (Iron-stained)

Silicon Dioxide (SiO2)

Likely weathered sandstone fragment

Sandstone, chiefly quartz (SiO₂) with feldspar and iron-oxide cement

Rounded quartz-rich pebble

Likely microcrystalline quartz (SiO₂), possibly milky quartz or a pale quartzite fragment

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Granite fragment

Granite, chiefly quartz (SiO₂), feldspar, and mica

Granite fragment

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

Granite fragment

Granite, chiefly quartz, feldspar, and mica

Granite fragment

Granite, chiefly quartz (SiO₂), feldspar, and mica

Granite fragment

Granite, chiefly quartz, alkali feldspar, plagioclase, and mica

Granite fragment

Felsic intrusive igneous rock; mainly quartz, alkali feldspar, plagioclase, and minor biotite/hornblende

Pebble / Gravel Fragment

Clastic Rock Fragment

River Pebble

Siliceous rock fragment

Concrete-like aggregate surface with embedded rock fragments

Anthropogenic concrete or exposed aggregate; not a natural rock specimen