Mineral (Biogenic)

Rounded reddish-brown pebble, likely iron-stained quartzite or chert

Quartzite (mostly SiO₂), possibly ferruginous chert

Rounded flint or chert pebble

Microcrystalline quartz (SiO₂), commonly chalcedony with possible impurities

Banded chert or jasper pebble

Microcrystalline quartz (SiO₂), likely chert/jasper with iron-oxide staining

Chert or silicified rock fragment

Microcrystalline quartz (SiO₂), likely chert with iron-oxide staining

Dark flint or chert

Microcrystalline quartz (SiO₂), chiefly chalcedony with possible moganite

Banded chert pebble

Microcrystalline quartz (SiO₂), likely ferruginous or jaspery chert

Pearl-embellished decorative cross

Pearl (biogenic calcium carbonate, predominantly aragonite) with rhinestone-mounted glass or synthetic gemstones

Flint (chert), likely brown flint

Microcrystalline quartz/chalcedony (SiO₂)

Pearl oyster shell with cultured pearls

Mollusk shell (likely Pinctada spp.) containing aragonite pearls, CaCO₃

Rounded brown chert or jasper pebble

Microcrystalline quartz (SiO₂), likely ferruginous chert/jasper

Tumbled chert or chalcedony pebble

Microcrystalline quartz (SiO₂), likely chert/chalcedony

Calcite

Calcite (CaCO₃)

Chert (or Flint)

Chert (cryptocrystalline quartz), SiO2

Fossilized cylindrical shell or bone fragment

Indeterminate biogenic carbonate or phosphatic fossil; possible fragment of a tubular shell (e.g., scaphopod) or hollow bone

Polished/tumbled chert or jasper pebble

Microcrystalline quartz (SiO₂), likely brown jasper/chert

Polished chert or jasper pebble

Microcrystalline quartz (SiO₂), likely chalcedony-rich chert/jasper

Beach-worn fossil bone or coral fragment

Indeterminate biogenic calcium-carbonate material; likely fossilized bone (hydroxyapatite) or coral (calcite/aragonite)

Flint

Chert (a form of cryptocrystalline quartz, chemical formula SiO₂)

Fossilized shell or bone fragment

Indeterminate biogenic carbonate/phosphate fossil; likely a fragment of fossil shell or small vertebrate bone

Calcite

Calcite (CaCO3)

Weathered fossiliferous limestone, likely coral or shell fragment

Calcite (CaCO₃), biogenic limestone; exact fossil taxon indeterminate from the image

Seashell fragment

Calcium carbonate (CaCO3)

Tumbled coral limestone

Biogenic calcarenite/coral limestone, predominantly calcium carbonate (CaCO₃; calcite/aragonite)

Amber Inlay Jewelry

Fossilized Resin (C10H16O)

Chert

Chert (microcrystalline quartz, SiO2)

Likely coral fragment or porous limestone

Calcareous biogenic carbonate, primarily calcite (CaCO₃); exact identification is uncertain from the image

Chert (or possibly Flint)

SiO2 (Silicon Dioxide)

Fossiliferous limestone pebble (probable coral or shell fossil)

Calcite (CaCO₃), commonly biogenic limestone; exact fossil taxon indeterminate from the image

Fossiliferous limestone (coral or shell-rich limestone)

Biogenic calcite limestone, mainly calcium carbonate (CaCO₃); exact fossil type is unclear from the image

Pebble (likely Quartz or Chert)

SiO₂ (Silicon Dioxide) - referring to the likely main mineral composition, Quartz. If it's chert, the scientific name remains SiO₂ with a microcrystalline structure.

Banded Iron Formation (BIF) with potential Stromatolite/Biogenic Trace

Ferruginous Chert / Banded Iron Formation (BIF)

Chert (Jasper or Flint variant)

Chert (composed of microcrystalline quartz, SiO2)

Cockle Shell (Fossil or Recent)

Class Bivalvia, Family Cardiidae (e.g., Cerastoderma edule for common cockle)

Bivalve Shell (Fossil or Contemporary)

Class Bivalvie (various genera and species of clams, cockles, etc.)

Gneiss or Schist

Gneiss or Mica Schist with Garnet

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

Tumbled granite

Granite, a coarse-grained felsic intrusive igneous rock

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

Pegmatite with Tourmaline and Quartz

Igneous Pegmatite

Granite

Granite (Phaneritic intrusive igneous rock)

Gypsum (variety Selenite or Alabaster)

Calcium sulfate dihydrate (CaSO4·2H2O)

Septarian Pebble

Septarian nodule / Concretion