Mineral, Specifically A Rock Fragment

Sandstone (with Rock Art)

Sandstone (Clastic Sedimentary Rock)

Weathered, iron-stained rock fragment

Unidentified silicate-rich rock; the image is insufficient for a reliable species identification

Lake Superior Agate

Chalcedony (SiO2 with iron impurities)

Red jasper (likely)

Jasper, an opaque microcrystalline variety of quartz (SiO₂), colored by iron oxides

Milky quartz in host rock

Quartz (SiO₂), likely a quartz vein or quartz-rich fragment

Quartz Druzy (Geode Fragment)

Silicon Dioxide (SiO2)

Uncertain green-brown mineral fragment

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

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Conglomerate

Conglomerate (SiO2 matrix with various silicate clasts)

Milky Quartz

Silicon Dioxide (SiO2)

Fossil bivalve or brachiopod in sedimentary rock

Unidentified fossil shell impression; likely a ribbed bivalve or brachiopod preserved in shale/siltstone

Milky Quartz Geode or Druzy Quartz

Silicon Dioxide (SiO2)

Sandstone and River Pebbles

Sedimentary Rock (Sandstone / Quartzite / Chert)

Iron-stained quartz-bearing rock

Quartz (SiO₂), likely with limonite/goethite iron oxides and possibly feldspar

Weathered granitic rock fragment

Likely granite or granodiorite; quartz–feldspar–mica aggregate

Uncertain small pale mineral fragment

Indeterminate; possibly calcite or a light-colored feldspar fragment

Pink Granite

Felsic Plutonic Rock

Weathered, iron-stained rock fragment

Unidentified iron-oxide-stained silicate rock; precise identification is not possible from the image

Pink chalcedony / quartz fragment (probable)

Microcrystalline quartz, SiO₂ (likely iron-stained chalcedony or quartzite)

Iron-rich rock fragment, possibly limonite/goethite

Limonite (mixture of hydrated iron oxides, commonly goethite, FeO(OH))

Breccia

Clastic Breccia (General mineral composition depends on fragments, often SiO2 or CaCO3)

Likely weathered quartz or feldspar grain

Uncertain; possibly quartz (SiO₂) or a feldspar mineral

Milky quartz

Quartz (SiO₂), likely massive or vein quartz

Gravel and Pebbles

Unconsolidated rock fragments / detrital sediment

Possible fossilized bone fragment

Indeterminate fossil bone; no species can be identified from this image

Rounded sandstone pebble

Quartz-rich sandstone (likely arkosic or lithic sandstone)

Fossilized tooth or bone fragment

Indeterminate fossil; possibly a small fossil tooth or mineralized bone, exact identification requires microscopy

Pink Granite

Phaneritic Felsic Igneous Rock (composed primarily of K-Feldspar, Quartz, and Plagioclase)

Granite (likely weathered)

Granite, a quartz–feldspar–mica intrusive igneous rock

Turquoise fragment

Turquoise — hydrated copper aluminum phosphate, CuAl₆(PO₄)₄(OH)₈·4H₂O

Small gray rock fragment

Undetermined; likely a common silicate-rich stone or concrete/road aggregate fragment

Quartz Geode

Silicon Dioxide (SiO2)

Granite fragment

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

Sandstone

Arenite

Sandstone (with potential fossil fragments)

Sandstone (SiO2 dominated with iron oxides)

Sandstone

Arenite (primarily SiO2)

Sandstone

Arenite (SiO2 primarily)

Small dark metallic-looking rock fragment

Undetermined; possibly iron oxide-rich material or a metallic mineral

River Pebble

Lithified rock fragment (variable composition)

Small weathered fossil or mineral fragment

Indeterminate; possibly fossilized shell, bone, or a pale carbonate mineral

Sandstone (with Iron Staining)

Arenite (primarily SiO2 with Fe2O3/FeO(OH) oxides)

Likely small iron-rich concretion or weathered mineral fragment

Indeterminate; possibly limonite/goethite-bearing material with quartz or feldspar