Industrial Byproduct (Anthropogenic Material)

Diamond (or Cubic Zirconia)

Carbon (C) or Zirconium Dioxide (ZrO2)

Grooved Maun Ball (Maul/Hammerstone-like Concretion)

Calcareous/Ferruginous Concretion in Sandstone Matrix

Ruby (set in a ring; possibly synthetic or imitation)

Corundum, Al₂O₃; red color is typically caused by chromium

Quartz Pebble

Silicon dioxide (SiO2)

Quartz Pebble

Silicon dioxide (SiO2)

Serpentine

Hydrous magnesium iron silicate, (Mg,Fe)3Si2O5(OH)4

Small dark metallic-looking rock fragment

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

Sandstone

Arenite (SiO2 primarily)

Quartz Pebble

Silicon Dioxide (SiO2)

Silver (Morgan Dollar)

Native Silver (Ag) - 90% Silver, 10% Copper alloy

Quartz Sand Gravel

Silicon Dioxide (SiO2)

Asphalt Concrete (Bituminous Pavement)

Aggregates in Bitumen Matrix

Diamond (or Diamond Simulant)

Carbon (C) if diamond, various if simulant (e.g., Cubic Zirconia ZrO2)

Coal

Combustible sedimentary rock

Crushed Stone Ballast

Crushed Limestone or Granite Aggregate

Quartzite

Quartzite (principally SiO2)

Black glassy volcanic rock, likely scoria or obsidian

Vesicular basaltic scoria (probable); possibly dark obsidian

Polished pietersite cabochon

Pietersite (brecciated fibrous quartz/chalcedony, commonly with riebeckite or crocidolite remnants)

Carved pyrite frog or toad

Pyrite (iron disulfide, FeS₂), likely a carved massive aggregate

Probable fossil-bearing rock or mineral concretion

Unidentified carbonate-rich concretion with a possible fossil inclusion

Rough Diamond

Diamond (Native Carbon, C)

Limestone

Calcium Carbonate (CaCO3)

Potassium-Rich Silicate Clay (inferred from biological context)

Phyllosilicate group (likely Illite or Smectite within surrounding soil substrate)

Tumbled magnesite

Magnesite (MgCO₃), likely compact or veined magnesite

Tumbled pale-green stone, likely prehnite or serpentine

Most consistent with massive prehnite, Ca₂Al₂Si₃O₁₀(OH)₂; serpentine is a possible alternative

Tektite (likely indochinite)

Natural silica-rich impact glass; predominantly amorphous SiO₂ with aluminum, iron, magnesium, calcium, and sodium

Clay Brick

Ceramic structural unit (Al2O3·2SiO2·2H2O as precursor)

Diamond

C

Sandstone (lithic/quartz variant)

Clastic sedimentary rock (SiO2 predominant)

Sandstone

Arenite (SiO2 principal)

Quartzite Pebble

Quartzite (SiO2)

Synthetic Sapphire and Ion-X Glass

Single-crystal Alumina (Al2O3) and Ion-strengthened Aluminosilicate Glass

Concrete

Hydrated Portland Cement Aggregate Composite

Tumbled, iron-stained quartz-rich pebble

Likely quartz/chalcedony with iron-oxide staining; exact rock type cannot be determined from the image

Sandstone Pebble

Arenite (Siliclastic sedimentary rock)

Sandstone (Ferruginous)

Clastic sedimentary rock (primarily SiO2 with Fe2O3 cement)

Sandstone

Arenite

Red Sandstone

Ferruginous Sandstone (SiO2 dominated with Fe2O3)

Red Sandstone

Sandstone (lithic arenite or arkose with iron oxide)

Pebble

Lithic fragment / Water-worn rock

Sandstone

Arenite (SiO2 principal composition)

Sandstone (Ferruginous)

Arenite with Iron Oxides