Biogenic Material

Greenschist

Greenschist (chlorite schist)

Orbicular jasper

Orbicular jasper (microcrystalline quartz/chalcedony with iron-oxide and volcanic inclusions)

Small iron-rich pebble, possibly hematite/limonite

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

Concrete with Exposed Aggregate

Anthropogenic conglomerate (Concrete)

Faience and Carnelian in Egyptian Revival Jewelry

Faience (quartz frit) and Carnelian (chalcedony, SiO2)

Brecciated Jasper or Agatized Dinosaur Bone

SiO2

Polished greenstone / serpentine (probable)

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

Sandstone (Ferruginous)

Arenite (with Iron Oxide)

Serpentine-rich metamorphic rock

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

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)

Beaded bracelet with likely quartz or glass beads

Uncertain; the pale beads may be quartz (SiO₂), but the image does not show diagnostic features

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

Possibly a polished pale-green gemstone cabochon (likely aquamarine or fluorite)

Undetermined from the image; aquamarine is blue-green beryl (Be₃Al₂Si₆O₁₈), while fluorite is CaF₂

Mixed gravel and small stones

Unsorted gravel; individual clasts are not identifiable from the image

Quartzite

Quartzite

Quartz-rich stone, possibly aventurine quartz or quartzite

Quartz (SiO₂), likely massive or microcrystalline; exact identification requires testing

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)

Weathered quartz-rich rock, likely feldspathic quartzite or quartz vein fragment

Quartzite dominated by quartz (SiO₂), with probable feldspar and iron-oxide staining

Tumbled dark stone, likely basalt

Basalt; primarily plagioclase feldspar, pyroxene, and commonly olivine

Schist

Schist; commonly mica schist, composed chiefly of muscovite/biotite mica with quartz and feldspar

Weathered quartzite cobble

Quartzite, composed predominantly of recrystallized quartz (SiO₂)

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)