Not A Natural Rock

Man-made Slag (Industrial Byproduct)

Anthropogenic Glassy Residue

Concrete / Anthropogenic Conglomerate

Man-made composite material (Portland cement, aggregate, and water)

Smoky quartz and clear/white quartz bead necklace

Quartz, silicon dioxide (SiO₂); smoky variety colored by irradiation-related defects

Weathered biotite granite or granitic gneiss

Felsic granitoid, chiefly quartz, K-feldspar, plagioclase, and biotite; possible gneissic deformation

Baked-clay ceramic fragment (likely brick or pottery)

Fired clay, primarily aluminosilicate minerals; not a natural rock

Weathered concrete or cementitious slab (not natural rock)

Artificial calcium-silicate cement composite; likely Portland cement concrete

Concrete-like aggregate surface with embedded rock fragments

Anthropogenic concrete or exposed aggregate; not a natural rock specimen

Green glass-like cabochon, likely synthetic glass or resin

Unidentified green transparent material; possibly molded glass, synthetic spinel, or resin

Bowling Ball (Brunswick T-Zone Deep Space)

Polyester resin / Polyurethane polymer

Fossil fish impression/cast (likely small ray-finned fish)

Unidentified Actinopterygii; possibly a fish fossil in laminated shale

Exposed aggregate concrete (stone-chip surface)

Portland-cement concrete containing natural aggregate; not a natural rock

Garnet ring

Likely almandine or pyrope garnet, an Fe–Mg–Al silicate in the garnet group; exact identity cannot be confirmed visually

Faceted colorless gemstone, likely cubic zirconia or diamond

Cubic zirconia (zirconium dioxide, ZrO₂) or diamond (carbon, C)

Weathered granite fragment

Granite, chiefly quartz (SiO₂), feldspar, and mica

Green-and-white terrazzo (likely serpentine/marble aggregate)

Composite decorative stone; probable serpentinite (Mg₃Si₂O₅(OH)₄) with white calcite marble fragments in cementitious matrix

Unidentified gray stone/concrete-like fragment

Indeterminate; likely a fine-grained carbonate or cementitious geological fragment

Red Painted Rock

Artificial Coated Lithic Fragment

Multi-stone gemstone ring

Likely faceted blue topaz or synthetic blue stone with clear stones, possibly cubic zirconia or diamond; metal setting appears silver-colored alloy

Angular gray rock fragments

Unidentified fine-grained rock; the image does not show diagnostic features sufficient for a specific identification

Concrete or asphalt-like aggregate surface with a dark fragment

Uncertain; likely artificial concrete containing mixed lithic aggregate, not a natural rock

Green aventurine cabochon earrings

Aventurine quartz (SiO₂), likely green quartzite with fuchsite mica

Blue glass-like bead or gemstone keychain ornament

Indeterminate; likely cobalt-blue glass or synthetic blue spinel, not identifiable as a natural mineral from the image

Parian marble sculpture fragment

Marble, predominantly calcite (CaCO₃), likely a fine-grained Greek island marble

Quartz pebble in concrete

Quartz (SiO₂), embedded in Portland-cement concrete

Smooth gray pebbles

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

Conglomeratic concrete or asphalt aggregate surface with dark bituminous chunks

Polymictic gravel aggregate; dark pieces likely bitumen/asphalt, not a natural rock

Carnelian (red-orange chalcedony) beads

Microcrystalline quartz, SiO₂; chalcedony colored chiefly by iron oxides

Unidentified gray rock fragment

Indeterminate from image; possibly quartz- or feldspar-rich silicate material

Quartz-rich pegmatite with drusy quartz

Quartz (SiO₂) in a granitic pegmatite, likely with feldspar and mica inclusions

Gray rock (possibly basalt or fine-grained granite)

Undetermined; no diagnostic minerals are visible

Likely pale limestone or calcite-rich rock

Calcite-bearing limestone; chiefly calcium carbonate (CaCO₃)

Goldstone (aventurine glass)

Synthetic copper-bearing soda-lime glass; commonly sold as red goldstone

Possible weathered basalt or iron-rich slag

Basalt, tentatively; composition likely plagioclase and pyroxene with possible magnetite

Goldstone (Red)

Aventurine Glass

Rounded river pebble, likely weathered sandstone or volcanic rock

Indeterminate fine-grained lithic clast; possible sandstone (quartz-rich)

Painted/tumbled stone specimens

Unidentified natural rock; likely a dark silicate stone and a weathered brown stone

Basalt Arrowhead (worked stone)

Aphanitic mafic volcanic rock (Basalt)

Unidentifiable Rock Fragment

Faceted glass-like gemstone (likely synthetic quartz or cubic zirconia)

Identification uncertain; possibilities include synthetic quartz (SiO₂) or cubic zirconia (ZrO₂)

Possible flint or slag fragment

Microcrystalline quartz (chalcedony), or iron-rich industrial slag

Emerald and diamond ring

Emerald: beryl, Be3Al2Si6O18, colored green by chromium and/or vanadium; surrounding stones appear to be diamonds, crystalline carbon (C)

Clear faceted gemstone, likely synthetic cubic zirconia

Cubic zirconia (zirconium dioxide, ZrO₂); visual identification is not definitive and diamond or synthetic moissanite are alternatives