Rock

Limestone

Calcium carbonate (CaCO3)

Quartzite

Metamorphic Quartz Arenite

Quartz (or Chert/Flint)

Silicon Dioxide (SiO2)

Sandstone

Sedimentary Rock (Quartz Sandstone)

Limestone

Calcareous sedimentary rock (CaCO3)

Granite

Granite (Intrusive Igneous Rock)

Quartzite

Metamorphic Quartzite (SiO2)

Granite

Felsic intrusive igneous rock

Granite

Felsic intrusive igneous rock

Flint / Chert (or fossiliferous nodule)

Microcrystalline quartz (SiO2)

Limestone

Calcium Carbonate (CaCO3)

Granite

Felsic intrusive igneous rock

Granite

Felsic intrusive igneous rock

Granite

Felsic intrusive igneous rock

Granite

Felsic intrusive igneous rock

Quartzite Pebble

Quartzite (SiO2)

Granite or Porphyritic Igneous Rock (weathered)

Granitoid

Rock Specimen

Unclassified rock specimen

Small rounded pebble, likely quartz-rich river or beach stone

Unidentified lithic pebble; exact rock type cannot be determined from the image

Sandstone

Clastic Sedimentary Rock

Granite

Intrusive Igneous Rock

Coal (Bituminous / Anthracite)

Organic Sedimentary Rock (Carbonaceous Rock)

Coal

Coal (Sedimentary Rock / Organic Rock)

Iron-rich breccia or weathered ironstone

Goethite–hematite-bearing limonite, possibly with quartz and altered rock fragments

Small pale stone, likely quartzite or limestone fragment

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

Gravel or Crushed Stone

Fragmented Aggregate Stone

Quartz Geode

Quartz (Silicon Dioxide, SiO2)

Red sandstone with pale weathered surface

Iron-oxide-stained quartz arenite (sandstone)

Weathered stone pebble (exact rock type indeterminate)

Unidentified fine-grained rock; composition cannot be determined from the image

Weathered granite or granitic gneiss fragment

Granite; chiefly quartz (SiO₂), feldspar, and mica, with iron-oxide weathering

Granite, likely weathered biotite granite

Phaneritic intrusive igneous rock composed chiefly of quartz, feldspar, and biotite amphibole

Weathered volcanic rock, likely andesite or basaltic-andesite

Fine-grained plagioclase–pyroxene volcanic rock; possible altered andesite (exact identification requires testing)

Granite or granitic gneiss

Quartz–feldspar–mica granitoid; possibly foliated gneiss

Weathered granite or granitic gneiss

Quartz–feldspar–mica granitoid; possibly weakly gneissic

Quartz Vein in Host Rock

Silicon Dioxide (SiO2) within metamorphic/igneous matrix

Mixed rock fragments, likely iron-stained quartz-rich material

Indeterminate mixture; visible pale fragments may be quartz or feldspar, with iron-oxide staining (goethite/limonite)

Granite

Granite (Phaneritic Quartz-Feldspar Plutonic Rock)

Unidentified dark gray rock fragment

Likely fine-grained basalt or andesite; exact identification requires testing

Rounded gray river pebble, likely fine-grained basalt or andesite

Basaltic-andesitic volcanic rock; commonly plagioclase feldspar, pyroxene, and minor iron oxides

Basalt

Aphanitic Mafic Volcanic Rock

Limestone

Calcium Carbonate (CaCO3)

Crushed Granite and Basalt

Phaneritic Igneous Rock / Aphanitic Igneous Rock