Sedimentary (Chemically Precipitated)

Chert Nodule in Limestone (Flint in Chalk)

SiO2 (Microcrystalline Quartz) in CaCO3 (Calcite)

Red Jasper

Microcrystalline Quartz (SiO2)

Limestone with Calcite Crystals

Sedimentary Rock containing Calcium Carbonate (CaCO3)

Hematite-rich ironstone concretion

Hematite (Fe₂O₃), likely mixed with goethite/limonite and silica

Orange Calcite

Calcium Carbonate (CaCO3)

Iron-rich concretion or weathered ironstone

Goethite–hematite limonite aggregate; commonly described as limonite or ironstone

Red Jasper

Silicon Dioxide (SiO2) with Hematite inclusions

Weathered limestone fragment

Limestone, predominantly calcite (CaCO₃), possibly porous bioclastic limestone

Honey calcite cluster

Calcite (calcium carbonate, CaCO₃)

Fossiliferous Limestone with Brachiopod

Limestone (Calcium Carbonate, CaCO3) with Phylum Brachiopoda fossil

Iron-rich concretion or weathered ironstone

Goethite–hematite-rich limonite (FeO(OH)·nH₂O / Fe₂O₃)

Weathered iron-rich concretion

Goethite–hematite limonite concretion, likely with quartz and clay minerals

Moqui Marbles

Ironstone Concretions (Hematite / Goethite / Sandstone)

Jasper

Microcrystalline Quartz (SiO2)

Fossiliferous Limestone with Rugose Coral

Calcite (CaCO3) containing a Rugosa (Horn Coral) fossil

Ferruginous Sandstone

Arenite with limonite/goethite cement

Ocean Jasper

Orbicular Jasper (Silicon Dioxide SiO2)

Chert Pebble

Microcrystalline Quartz (SiO2)

Chert (Flint / Jasper)

Microcrystalline Quartz (SiO2)

Sandstone (Ferruginous)

Arenite (primarily SiO2 with Fe2O3 staining)

Iron-rich sandstone (Gozan/Ironstone)

Ferruginous Sandstone (clastic sedimentary rock)

Pyrite-rich sulfide ore (likely pyrite with chalcopyrite)

Pyrite, FeS₂; possible chalcopyrite, CuFeS₂, and minor quartz or sphalerite

Banded calcite (likely cave deposit or vein fragment)

Calcite, CaCO₃

Rounded limestone pebble

Micritic or bioclastic limestone, primarily calcium carbonate (CaCO₃)

Jasper pebble (possibly Red Jasper or Lake Superior Agate/Jasper mix)

Silicon Dioxide (SiO2) with Hematite inclusions

Red Jasper

Silicon Dioxide with Iron Oxide (SiO2 + Fe2O3)

Jasper with Quartz inclusion

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Iron-rich concretion (probable limonite/goethite concretion)

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

Septarian Nodule (Micro-fragment)

Septarian Nodule / Concretion (CaCO3 + CaMg(CO3)2 + Quartz)

Honey calcite (orange calcite)

Calcite, calcium carbonate (CaCO₃)

Sandstone with Ironstone Concretion

Arenite with Hematite/Goethite nodules (Fe2O3 / FeO(OH))

Blue apatite (likely dyed or enhanced)

Apatite group; fluorapatite, Ca5(PO4)3F, is the common blue variety

Ferruginous Sandstone (Gritstone)

Clastic sedimentary rock with iron-rich cement (FeO(OH)·nH2O)

Chert / River Jasper

Microcrystalline Quartz (SiO2)

Pyrite (Fool's Gold)

Iron Disulfide (FeS2)

Quartz-rich polymict conglomerate (possibly hydrothermal breccia)

Clast-supported polymict conglomerate dominated by quartz; includes chalcedony/quartz and dark lithic clasts

Iron-rich concretion or weathered ironstone pebble

Goethite–hematite limonite concretion (FeO(OH), Fe₂O₃, and hydrated iron oxides)

Weathered iron-rich concretion or ironstone nodule

Goethite–hematite limonite concretion (FeO(OH), Fe₂O₃, and hydrated iron oxides)

Tufa

Calcareous Tufa (CaCO3)

Fossilized Limestone with Crinoid Stem

Carboniferous Limestone (containing Crinoidea ossicles)

Yellow Calcite (Banded)

Calcium Carbonate (CaCO3)

Orange Calcite

Calcium Carbonate (CaCO3)