Igneous, Sedimentary, Metamorphic

Petrified wood

Silicified wood; commonly quartz/chalcedony (SiO₂) replacing organic tissue

Quartz

SiO2 (Silicon dioxide)

Quartz

Silicon Dioxide (SiO2)

Unidentifiable Specimen

Undetermined

Quartz

Quartz (SiO₂)

Mixed mineral and rock specimen collection

Mixed assemblage, visibly including quartz, chalcedony/agate, feldspar, mica, dark mafic rocks, and possibly calcite or gypsum

Mixed collection of common river stones

Varied lithologies, visibly including quartz-rich rock, dark mafic rock, sandstone, and purple quartz-bearing material

Mixed river stones and gravel

Polymictic alluvial clasts; individual pieces may include quartzite, granite, basalt, sandstone, limestone, and slate

Mixed rock collection

Labeled specimens appear to include iron-rich rock, schist, basalt, serpentinite, and shale

Mixed river-worn rock collection

Uncertain; likely quartzite, sandstone, basalt, and weathered granite or gneiss

Assorted Beach Rocks and Pebbles

Various (Granite, Basalt, Quartz, Conglomerate, etc.)

Mixed stream gravel and common rock specimens

Predominantly quartz-rich granitoid, quartzite, sandstone, shale/slate, and mafic volcanic fragments; exact species cannot be determined confidently from the image

Mixed rock and mineral specimen collection

Mostly undetermined from the photograph; apparent quartz-rich rocks, sandstone, granite/gneiss, and possibly iron-oxide-bearing specimens

Mixed river-worn rock and mineral collection

Mostly quartz/quartzite, feldspar-bearing granitoid, chert, and mafic volcanic rocks; exact species vary by pebble

Mixed Quartz and River Pebbles (Stone Collection)

Mixed assortment containing mainly Silicon Dioxide (SiO2)

Mixed rock and mineral collection

Mixed lithologies; likely quartz, feldspar, basalt, granite, chert, sandstone, and metamorphic rocks

Mixed Tumbled Gemstones and River Rocks

Mixed Decorative Stones (predominantly Silicon Dioxide - SiO2 variants)

Wishing Rock (Quartz Vein in Host Rock)

Silicon dioxide (SiO2) vein in various host rocks

Unidentified brown rock fragment

Indeterminate from image; likely a weathered iron-rich lithic fragment

Magnetite (Lodestone variety)

Magnetite (Fe3O4)

Tumbled milky quartz

Quartz, SiO₂; trigonal crystal system

Quartz (likely milky or iron-stained quartz)

Quartz, silicon dioxide (SiO₂)

Milky quartz cluster

Quartz (silicon dioxide, SiO₂)

Tumbled milky quartz

Quartz (silicon dioxide, SiO₂)

Milky quartz crystal cluster

Quartz (silicon dioxide, SiO₂)

Likely milky quartz

Quartz (silicon dioxide, SiO₂)

Clear quartz crystal pendant

Quartz (silicon dioxide, SiO₂)

Blue Apatite

Apatite (Group), Ca5(PO4)3(F,Cl,OH)

Clear quartz (rock crystal)

Quartz, crystalline silicon dioxide (SiO₂)

Red coral (coral beads)

Precious coral, usually Corallium spp.; composed primarily of calcium carbonate (calcite)

Milky quartz

Quartz (silicon dioxide, SiO₂)

Quartz

Silicon dioxide (SiO2)

Tumbled clear quartz

Quartz (SiO₂)

Tumbled clear quartz

Quartz (silicon dioxide, SiO₂)

Small quartz-rich mineral fragment

Quartz (SiO₂), possibly milky or chalcedonic quartz

Magnetite

Magnetite (Fe3O4)

Quartz pebble

Silicon dioxide (SiO2)

Clear Quartz

SiO2 (Silicon Dioxide)

Mica

Mica group (often Muscovite or Biotite)

Clear Quartz

Silicon Dioxide (SiO2)

Milky quartz

Quartz, silicon dioxide (SiO₂)

Blue Apatite

Calcium phosphate fluoride, Ca5(PO4)3(F,Cl,OH)