Anthropogenic Material

Small iron-rich pebble, possibly hematite/limonite

Hematite (Fe₂O₃) or goethite–limonite (FeO(OH)·nH₂O)

Polished greenstone / serpentine (probable)

Serpentinite, dominated by serpentine-group minerals such as antigorite, lizardite, or chrysotile

Serpentine-rich metamorphic rock

Serpentinite; chiefly antigorite/lizardite/chrysotile, commonly with magnetite and carbonate

Sandstone (Ferruginous)

Arenite (with Iron Oxide)

Chert Pebble

Cryptocrystalline Quartz (SiO2)

Diamond

C

Diamond (or Diamond Simulant)

Carbon (C)

Chert (Flint)

Silicon dioxide (SiO2)

Chert/Flint nodule or weathered river rock

Microcrystalline or cryptocrystalline silica (SiO2)

Likely obsidian fragment

Volcanic glass; predominantly SiO₂ (amorphous, rhyolitic composition)

Iron Meteorite / Chondrite (Possible)

Extraterrestrial stony-iron or chondritic meteorite

Chert (Grey-Green Var.)

Silicon Dioxide (SiO2)

Brecciated Jasper or Agatized Dinosaur Bone

SiO2

Limestone Gravel

Sedimentary Calcium Carbonate (CaCO3)

Diamond

Diamond (pure Carbon, C)

Diamond

Carbon (C)

Quartz Vein in Siltstone

SiO2 (Quartz) on clastic sedimentary matrix

Quartz (Iron-stained)

Silicon Dioxide (SiO2)

Diamond (in Jewelry)

Carbon (C)

Gastropod Internal Mold (Steinkern)

Class Gastropoda fossil mold (Phylum Mollusca)

Mixed gravel and mineral fragments

Polymictic unconsolidated sediment; likely quartz, feldspar, chert, mica, and lithic fragments

Tumbled brown quartz crystal (likely smoky quartz or iron-stained quartz)

Quartz, silicon dioxide (SiO₂)

Kyanite blade

Kyanite, Al₂SiO₅

Polished red/purple tourmaline

Elbaite tourmaline, complex borosilicate: Na(Li,Al)₃Al₆(BO₃)₃Si₆O₁₈(OH)₄

Fossilized coral or silicified organic limestone

Likely fossil coral (Scleractinia/Tabulata) replaced or cemented by calcite and silica; exact identification requires close examination

Mixed tumbled gravel and quartz-rich sandstone

Primarily quartz (SiO₂), feldspar, and lithic sedimentary fragments; one piece appears to be quartz-rich sandstone

Conglomerate

Conglomerate Rock

Milky Quartz

Silicon Dioxide (SiO2)

Coquina

Bioclastic Limestone (Coquina)

Diamond

Diamond (pure carbon, C)

Tumbled yellow jasper (likely yellow calcite or serpentine)

Microcrystalline quartz, SiO₂, if jasper; appearance may also fit calcite, CaCO₃, or serpentine-group minerals

Tumbled green jasper (probable serpentine-rich stone)

Jasper, microcrystalline quartz (SiO₂), possibly mixed with serpentine or chlorite

Diamond (or Diamond Simulant)

C (Carbon) or synthetic equivalent

Diamond

C (Carbon)

Diamond (or Diamond Simulant)

Carbon (C) if diamond, various if simulant

Chert or Chalcedony

Microcrystalline Quartz (SiO2)

Weathered gray-green metamorphic rock, likely serpentinite or altered basalt

Serpentinite, chiefly serpentine-group minerals (antigorite/lizardite); identification is provisional from the photograph

Weathered quartz-rich rock, possibly quartzite or granite

Indeterminate; likely quartz–feldspar aggregate, possibly granitic gneiss or quartzite

Serpentinite pebble

Serpentinite, dominated by serpentine-group minerals (antigorite, lizardite, or chrysotile), commonly with magnetite and carbonate veins

Obsidian (likely black volcanic glass)

Obsidian; primarily amorphous volcanic silica glass, approximately SiO₂-rich rhyolitic composition

Chalcedony (likely agate or chert)

Microcrystalline quartz, SiO₂

Banded calcite (likely cave deposit or vein fragment)

Calcite, CaCO₃