Sedimentary (Chemically Precipitated Mineral)

Light-colored quartz pebble

Quartz, silicon dioxide (SiO₂)

Weathered iron-rich concretion (probable limonite/goethite)

Limonite–goethite aggregate, approximately FeO(OH)·nH₂O

Polished banded agate

Agate, microcrystalline quartz (SiO₂; chiefly chalcedony)

Sandstone

Arenite (SiO2 based)

Weathered iron-rich mineral concretion

Likely limonite/goethite concretion (hydrated iron oxides), possibly a weathered ironstone fragment

Likely quartz-rich rock fragment

Probably microcrystalline quartz (SiO₂), possibly a pale chert or quartzite fragment

Honey calcite cluster

Calcite (calcium carbonate, CaCO₃)

Iron-oxide-rich breccia or weathered ironstone

Hematite–goethite ironstone, likely brecciated and quartz-bearing

Chert

Microcrystalline Quartz (SiO2)

Banded iron formation pebble

Banded iron formation (BIF), chiefly hematite/magnetite with chert or jasper

Coquina

Biogenic Limestone (Coquina)

Iron-stained milky quartz

Quartz (SiO₂), locally limonite/goethite-stained

Fluorite (or Green Calcite)

Calcium Fluoride (CaF2)

Quartz vein specimen

Quartz (SiO₂), likely drusy or massive quartz on host rock

Dolomite on Prehnite (Saddle-shaped Dolomite)

Dolomite [CaMg(CO3)2] on Prehnite [Ca2Al(AlSi3O10)(OH)2]

Iron-rich concretion (probable limonite/goethite concretion)

Hydrated iron oxides, chiefly limonite (FeO(OH)·nH₂O) and goethite (FeO(OH))

Blue apatite (likely rough/tumbled specimen)

Apatite group, commonly fluorapatite — Ca5(PO4)3F

Chert (Quartzite-rich River Pebble)

Silicon Dioxide (SiO2)

Chert (Common Variety, Jasper)

Microcrystalline Quartz (SiO2)

Chert / Microcrystalline Quartz

Chert (SiO2)

Chert (Light Grey / Flint variant)

Cryptocrystalline Quartz (SiO2)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Jasper (specifically Bloodstone or Heliotrope variety)

Silicon Dioxide (SiO2) with iron oxide inclusions

Quartz-veined Limestone

Sedimentary limestone with quartz/calcite veinlets

Brown chert or flint pebble

Microcrystalline quartz (SiO₂), likely chert

Aragonite Star Cluster

Aragonite (CaCO3)

Assorted Tumbled Gemstones

Mixed oxides and silicates (including Quartz, Chalcedony, and Feldspar variants)

Jasper

Microcrystalline Quartz (SiO2)

Red Jasper

Silicon dioxide with iron inclusions (SiO2)

Banded Chert / Agate

Silicon Dioxide (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Iron-rich concretion or weathered ironstone pebble

Goethite/limonite-bearing ironstone; commonly an iron-oxide concretion (FeO(OH)·nH₂O, variable)

Weathered limestone or dolostone

Calcite-rich limestone (CaCO₃), possibly dolomite-bearing

Tumbled limestone or calcite-rich stone

Limestone, predominantly calcite (CaCO₃); exact identification is uncertain from the photograph

Chert (Nodule)

Silicon dioxide (SiO2) - Cryptocrystalline Quartz

White Quartz Pebble

Silicon Dioxide (SiO2)

Chrysocolla

Hydrated copper phyllosilicate, (Cu,Al)2H2Si2O5(5)nH2O

Small translucent quartz pebble

Quartz (silicon dioxide, SiO₂), possibly milky or chalcedonic quartz

Aragonite

Aragonite (CaCO3)

Chert / Flint Pebble with Fossil Cavity

Silicon Dioxide (SiO2)

Banded iron formation fragment (likely jasper-rich ironstone)

Banded iron formation (BIF), commonly hematite/goethite with chert or jasper; Fe₂O₃/FeO(OH) and SiO₂

Veined Limestone (Micrite) with Quartz/Calcite Veins

Calcium Carbonate (CaCO3) with Silicate or Carbonate inclusions