Sedimentary Or Igneous Fragment

Quartz / Common Gravel

Silicon Dioxide (SiO2)

Oyster shell fragment

Ostreidae shell; primarily calcite (CaCO₃)

Milky quartz fragment

Quartz (silicon dioxide, SiO₂)

Limestone Nodules or Chert

Sedimentary rock fragment

Unidentified greenish-gray rock fragment

Tentatively altered basalt or basaltic volcanic rock; mineral identification requires testing

Tourmaline-rich schist (likely black tourmaline)

Schist containing schorl, Fe-rich NaFe3Al6(BO3)3Si6O18(OH)4

Chalcedony (Agate/Chert variety)

Silicon Dioxide (SiO2)

Mixed Rock and Mineral Collection

Multiple geological specimens

Likely mica schist

Mica-rich schist, probably muscovite–biotite schist

Weathered mica-rich rock, likely mica schist

Mica schist, composed mainly of muscovite and/or biotite with quartz and feldspar

Gneiss

Gneiss (Metamorphic Rock)

Quartz Crystal Fragment

Silicon Dioxide (SiO2)

Quartz crystal fragment

Quartz, silicon dioxide (SiO₂)

Quartz (Small Fragment)

Silicon Dioxide (SiO2)

Reddish-brown mica-rich schist (likely biotite schist)

Biotite schist; mica-rich metamorphic rock, commonly composed of biotite, quartz, and feldspar

Foliated metamorphic rock, likely schist or gneiss

Quartz–mica schist/gneiss; exact identification requires close examination of mineral grains

Clear Quartz Fragment

Quartz (Silicon Dioxide, SiO2)

Sedimentary Pebble

Sedimentary Rock Fragment

Pyrite (Fool's Gold)

Iron Disulfide (FeS2)

Polished garnet-bearing metamorphic rock

Likely garnet mica schist or garnet-bearing gneiss; garnet is commonly almandine, Fe₃Al₂(SiO₄)₃

Garnet-bearing schist or gneiss

Garnet-mica schist/gneiss; chiefly quartz, feldspar, mica, and almandine–pyrope garnet

Granite fragment

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

Weathered quartz-rich metamorphic rock, likely gneiss or quartzite

Quartz (SiO₂)-bearing gneiss; exact identification requires a fresh surface and tests

Banded metamorphic rock, likely schist or gneiss

Foliated quartz–feldspar–mica rock; exact mineral identification requires sampling

Quartz-rich pebble

Mostly quartz (SiO₂), possibly a quartzite or vein-quartz fragment

Sedimentary Rock (Limestone or Siltstone pebble)

Sedimentary rock fragment

Quartz Cluster (Likely Ferruginous)

Silicon Dioxide (SiO2)

Likely quartz fragment

Quartz (silicon dioxide, SiO₂), possibly milky quartz or quartz-rich rock

Gravel / Crushed Stone

Aggregate (mixed mineral rock fragments)

Gneiss

Gneiss

White quartz fragment

Quartz (silicon dioxide, SiO₂)

Quartz (Small Fragment)

Silicon Dioxide (SiO2)

Weathered quartz-rich rock fragment

Likely quartz-bearing sandstone or granitic rock; exact identification is uncertain from the image

Quartz (or Chalcedony) Specimen

Silicon Dioxide (SiO2)

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Unknown dark mineral/rock fragment

Indeterminate; possibly a dark sulfide mineral or slag-like geological fragment

Fossilized shell fragment

Indeterminate fossil mollusk; likely a silicified or mineral-replaced bivalve/gastropod fragment

Small weathered rock fragment

Unidentified fine-grained, iron-stained rock; specific mineralogy cannot be determined from the image

Mica schist (likely biotite-rich schist)

Mica schist, composed chiefly of mica-group minerals (likely biotite) with quartz and feldspar

Weathered dark stone, possibly basalt

Basalt; commonly plagioclase feldspar, pyroxene, and minor olivine

Healer's Gold (Pyrite and Magnetite in Schist)

Magnetite (Fe3O4) and Pyrite (FeS2) in Mica Schist

Fossilized bone fragment (probable mammalian tooth or bone)

Mineralized bone, commonly hydroxyapatite [Ca5(PO4)3(OH)] replaced or impregnated by silica/calcite