Not A Rock Or Mineral

Possibly garnet-bearing rock fragment

Unidentified reddish-brown mineral or rock; the image is insufficient for a reliable species identification.

Gneiss

Felsic, quartz–feldspar gneiss

Rounded granitic gneiss pebble

Quartz–feldspar–biotite gneiss (tentative; exact identification requires closer inspection)

Serpentine

Serpentine subgroup (Mg,Fe)3Si2O5(OH)4

Serpentine

(Mg,Fe)3Si2O5(OH)4

Quartz with Iron Staining

Silicon Dioxide with Iron Oxides (SiO2 + Fe2O3)

Coarse-grained gray metamorphic rock, likely gneiss

Biotite–quartz–feldspar gneiss (probable)

Sandstone

Arenite

Druzy Quartz on Limestone

Silicon Dioxide (SiO2) on Calcium Carbonate (CaCO3)

Abbey Bominable (Monster High character)

Anthropomorphic Yeti / Digital Animation

Granite

Intrusive Igneous Rock

Possible milky quartz vein or nodule

Quartz (SiO₂), provisionally identified from the visible white translucent material

Basalt with Quartz Vein

Extrusive Igneous Rock / Volcanic Rock

Sedimentary Rock (Limestone or Siltstone pebble)

Sedimentary rock fragment

Quartz River Pebble

Silicon Dioxide (SiO2)

River Rock

Sedimentary clast

Likely garnet-bearing metamorphic rock

Garnet-bearing schist or gneiss; the visible dark crystal may be almandine garnet (Fe₃Al₂(SiO₄)₃)

Geode (Quartz / Chalcedony Geode)

SiO2 (Silicon Dioxide)

Generic Rock Sample

Undetermined geological specimen

Granite Pebbles

Granite (composed primarily of Quartz SiO2, Feldspar (KAlSi3O8 – NaAlSi3O8 – CaAl2Si2O8), and Mica)

Greenstone (likely altered mafic rock)

Chlorite- and amphibole-bearing metabasalt; exact identification requires testing

Rounded mixed-grain river pebble, likely granitic rock

Granite (tentative; exact rock type cannot be confirmed from the photograph)

Vesicular Basalt

Vesicular Basalt

Small rounded pebble

Unidentified lithic pebble; composition cannot be determined from the image

Smooth gray pebbles

Unidentified rounded rock fragments; composition cannot be determined from the image

Bauxite Ore

Hydrated aluminum oxides (e.g., Gibbsite Al(OH)3, Boehmite ̲̲̲̲AlOOH, Diaspore ̲̲̲̲AlOOH)

Red Sandstone

Sedimentary rock primarily composed of quartz sand grains

Likely tumbled greenstone (identity uncertain)

Greenstone: metamorphosed mafic volcanic rock, commonly composed of chlorite, actinolite, and epidote

Quartz Geode

Silicon Dioxide (SiO2)

Sandstone

Clastic sedimentary rock (primarily SiO2)

Small brown mineral or rock fragment (not identifiable from the image)

Undetermined; the specimen is too small and lacks visible diagnostic features for reliable identification

Small brown mineral or rock fragment

Undetermined; the image lacks enough detail for a reliable identification

Druzy quartz on matrix

Quartz (SiO₂), likely microcrystalline-to-fine crystalline drusy quartz

Crushed Granite and Basalt

Phaneritic Igneous Rock / Aphanitic Igneous Rock

Geode

Quartz nodule / Chalcedony-lined cavity

Quartz-rich geode or mineralized cavity in host rock

Likely a quartz-bearing geode; the pale crystals may be quartz (SiO₂), but the photo is not detailed enough for a firm identification.

Quartz with Sericite and Cinnabar

Silicon Dioxide (SiO2) with muscovite/sericite and mercury sulfide (HgS)

Likely greenstone (chlorite-rich metamorphic rock)

Greenstone, commonly altered basalt containing chlorite, epidote, and actinolite

Granite

Granite

Milky quartz vein in a host rock

Quartz (SiO₂), likely vein quartz; the gray host rock cannot be identified confidently from the image

Sandstone Pebble with Mineral Encrustation

Quartz Sandstone with Calcite/Halite Crust

Sandstone with Iron Banding

Arenite with Hematite or Limonite staining (SiO2 with Fe2O3)