Sedimentary (Chemically Precipitated)

Brown chert or flint pebble

Microcrystalline quartz (SiO₂), likely chert

Banded iron formation fragment (likely hematite–magnetite ironstone)

BIF; chiefly hematite (Fe₂O₃), magnetite (Fe₃O₄), and silica as microcrystalline quartz (SiO₂)

Chert (Quartzite-rich River Pebble)

Silicon Dioxide (SiO2)

Chert (Common Variety, Jasper)

Microcrystalline Quartz (SiO2)

Chert / Microcrystalline Quartz

Chert (SiO2)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Likely calcite fragment

Calcite (calcium carbonate, CaCO₃)

Calcite crystal fragment

Calcite (calcium carbonate, CaCO₃)

Honey calcite crystal

Calcite (calcium carbonate, CaCO₃)

Limonite (Ironstone)

Limonite (FeO(OH)·nH2O)

Orange Calcite

Calcium Carbonate (CaCO3)

River Chalcedony / Agate

Chalcedony (Silicon Dioxide, SiO2)

Carnelian Agate

Carnelian (Silicon Dioxide - SiO2)

Weathered limestone or dolostone

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

Chert (Nodule)

Silicon dioxide (SiO2) - Cryptocrystalline Quartz

Banded iron formation (iron-rich jasper/chert)

Banded iron formation, chiefly quartz (SiO₂) with hematite, magnetite, and/or goethite (Fe oxides/hydroxides)

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

River Pebble (Greywacke or Chert mix)

Silicon Dioxide (SiO2) with varying mineral impurities

Chert Pebble with Quartz Veining

Microcrystalline Quartz (SiO2)

Quartz in Matrix

Silicon Dioxide (SiO2) in host rock matrix

Quartz

Silicon Dioxide (SiO2)

Red Jasper Pebble

Silicon Dioxide (SiO2) with Iron Oxide inclusions

Quartz (Milky / Massive Quartz)

Silicon Dioxide (SiO2)

Pyrite

Iron Sulfide (FeS2)

Green Calcite

Calcium Carbonate (CaCO3)

Orange Calcite

Calcium Carbonate (CaCO3)

Quartz on Limestone

Silicon Dioxide (SiO2) on Calcium Carbonate (CaCO3)

Chert or flint nodule

Microcrystalline quartz (SiO₂), likely chalcedony-rich chert

Chert with Manganese Dendrites / River Silt Overlays

Cryptocrystalline Quartz (SiO2) with Manganese Oxides

Liesegang Banded Sandstone (Concretion / Weathered Pebble)

Sandstone showing Liesegang rings / Weathering rind (SiO2 with iron oxides)

Banded iron formation (ironstone)

Banded iron formation, chiefly hematite/magnetite with chert (SiO₂)

Banded Iron Formation (BIF)

Banded Iron Formation with Hematite and Jasper

Sandstone

Arenite (Sedimentary Rock)

Dead Sea Salt Crust

Halite (NaCl)

Quartz Druzy / Quartz Crystal Cluster

Silicon Dioxide (SiO2)

Flint (Chert)

Cryptocrystalline Silica (SiO2)

Ferruginous Sandstone (Ironstone)

Sedimentary rock with Limonite/Goethite cement

Peach/orange calcite cluster

Calcite (CaCO₃), likely botryoidal or scalenohedral aggregate

Milky or Iron-Stained Quartz

Quartz (Silicon Dioxide, SiO2)

Orange Calcite

Calcium Carbonate (CaCO3)

Likely calcite specimen

Calcite, calcium carbonate (CaCO₃)