Organic Material (Likely A Fruit Or Berry)

Chert / Flint

Chert (Silicon Dioxide, SiO2)

Polished black stone, likely black obsidian

Obsidian (volcanic glass), chiefly silica-rich rhyolitic composition

Chert (Flint variety)

Chert (Microcrystalline or Cryptocrystalline Quartz), SiO2

Chert

Microcrystalline Quartz (SiO2)

Graphite

Graphite (Native Carbon, C)

Tumbled purple quartzite

Quartzite; predominantly crystalline SiO₂ with minor iron-oxide or other mineral impurities

Likely galena-bearing ore

Galena (lead sulfide, PbS), possibly mixed with quartz or other sulfides

Blue-green fluorite (likely tumbled/polished)

Fluorite, calcium fluoride (CaF₂)

Arid Sandy Loam

Arenosols / Regosols

Quartz (Gravel fragment)

Quartz (Silicon Dioxide, SiO2)

Limestone (Fossiliferous)

Sedimentary Carbonate Rock (CaCO3)

Fossiliferous Limestone

Sedimentary rock containing Indeterminate Fossil remains (likely Crinoid stem or Bryozoan fragment)

Likely chlorite-bearing schist (possibly greenschist)

Chlorite–quartz–mica schist; commonly contains muscovite/biotite and feldspar

Quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly quartz (SiO₂), with minor iron-oxide and mica impurities

Likely weathered quartz-bearing rock (uncertain identification)

Possibly quartz-rich granite or granitic aplite; exact identification requires a clearer, larger image and tests

Polished dark stone, likely basalt

Basalt; chiefly plagioclase feldspar, pyroxene, and commonly olivine

Yellow Chert (River Stone)

Microcrystalline Quartz (SiO2)

Sandstone (likely Quartzose Sandstone)

Arenite (SiO2 principal composition)

Sandstone (likely Graywacke or Arkose)

Clastic Sedimentary Rock (primarily SiO2 with various lithic fragments)

Weathered rhyolite or felsic volcanic rock

Rhyolite, commonly quartz–alkali feldspar–plagioclase with iron-oxide alteration

Weathered quartz-rich granitoid (likely granite or granodiorite)

Granite–granodiorite; chiefly quartz (SiO₂), feldspar, and minor mica/amphibole

Tumbled pale greenish stone, likely serpentine or altered limestone

Probable serpentine-group rock (antigorite/lizardite), possibly serpentinite; identification is visual only

Polished pink-and-gray stone, likely rhodonite-bearing rock

Rhodonite (MnSiO₃) in a manganese-rich metamorphic matrix; exact identification requires testing

Sandstone (likely Graywacke or Lithic Sandstone)

Clastic Sedimentary Rock

Chert

Microcrystalline Quartz (SiO2)

Polished dendritic agate or jasper

Microcrystalline quartz (SiO₂), likely chalcedony with manganese-oxide dendrites

Chert or flint nodule

Microcrystalline quartz (SiO₂), likely chalcedony-rich chert

Sodalite-bearing rock, likely sodalite-rich syenite or sodalite in feldspathic matrix

Sodalite, Na₈(Al₆Si₆O₂₄)Cl₂, with probable feldspar and accessory minerals

Likely obsidian (possibly tektite or slag glass)

Volcanic glass; primarily SiO₂, noncrystalline

Iridescent coated quartz (likely synthetic/display gemstone)

Quartz, silicon dioxide (SiO₂), likely faceted and surface-coated; exact material cannot be confirmed visually

Pink chalcedony (likely rough agate/chalcedony)

Microcrystalline quartz, SiO₂; chalcedony variety, possibly iron-bearing

Polished green serpentine (likely antigorite-rich)

Serpentinite; chiefly serpentine-group minerals, Mg₃Si₂O₅(OH)₄, with possible chlorite, magnetite, and talc

Basaltic volcanic pebble

Fine-grained mafic igneous rock, chiefly plagioclase and pyroxene, commonly with olivine and iron-titanium oxides

Chert / River Stone

Microcrystalline Quartz (SiO2)

Tumbled basalt (likely)

Basalt; primarily plagioclase feldspar, pyroxene, and commonly olivine

Dark weathered pebble, likely basalt

Basalt (fine-grained mafic volcanic rock; typically plagioclase, pyroxene, and olivine)

Basalt Pebble

Mafic Igneous Rock (Basalt)

Milky Quartz in Conglomerate Matrix

Silicon Dioxide (SiO2) within Clastic Sedimentary Rock

Petrified Wood

Silicified Wood (SiO2)

Wood Beads (Palmwood/Ebony)

Various species for wood, but often refers to woods like Palmwood (e.g., Borassus flabellifer) or Ebony (Diospyros spp.) for their distinctive grain and hardness.

Chert (variant Flint)

Silicon Dioxide (SiO2)

Brecciated jasper/chalcedony

Silica-rich breccia composed mainly of microcrystalline quartz (SiO₂), with iron-oxide and possibly epidote or chlorite inclusions