Sedimentary (Chemically Precipitated Mineral)

Orange Calcite

Calcium Carbonate (CaCO3)

Yellow Calcite

Calcium Carbonate (CaCO3)

Ironstone pebble (likely limonite/goethite-rich)

Limonite, a mixture of hydrated iron oxides; commonly dominated by goethite (α-FeO(OH))

Likely limestone fragment

Calcite-rich limestone (primarily CaCO₃); exact identification is uncertain from the image

Light-colored, weathered rock (possibly limestone)

Calcite-rich limestone, likely; precise identification is not possible from the image alone

Black Chert River Stone

Cryptocrystalline Quartz (SiO2)

Chert

Microcrystalline Quartz (SiO2)

Chert (Chalcedony)

Silicon Dioxide (SiO2)

Chert (Flint)

Microcrystalline Quartz (SiO2)

River Pebble (Greywacke or Chert mix)

Silicon Dioxide (SiO2) with varying mineral impurities

Limonite (Ironstone)

Hydrated Iron(III) Oxide-hydroxide (FeO(OH)·nH2O)

Quartz-rich rock, possibly milky quartz

Quartz (SiO₂); the photo may show a quartz-rich rock, but its texture is not clear enough to determine a specific rock name.

Yellow Calcite

Calcite (Calcium Carbonate, CaCO3)

Peach/orange calcite cluster

Calcite (CaCO₃), likely botryoidal or scalenohedral aggregate

Fossiliferous Limestone

Calcium Carbonate (CaCO3) with Biogenic Inclusions

Chert (Flint)

Chert (SiO2)

Chert (Flint) Nodule

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Banded iron formation (iron-rich jasper/chert)

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

Quartz Geode (Unbroken)

Silicon Dioxide (SiO2)

Calcite

Calcium Carbonate (CaCO3)

Hematite

Iron(III) oxide (Fe2O3)

Orange Calcite

Calcium Carbonate (CaCO3)

Quartz Geode / Druzy Quartz Node

Silicon Dioxide (SiO2)

Honey-brown calcite crystal cluster

Calcite (CaCO₃), likely dogtooth or scalenohedral calcite

Calcite crystal cluster

Calcite — calcium carbonate, CaCO₃

Red Jasper Pebble

Opaque microcrystalline Quartz (SiO2) with Iron Oxide

Red Jasper

Microcrystalline Quartz (Chalcedony), SiO2

Limestone

Calcium Carbonate (CaCO3)

Banded Chert

Silicon Dioxide (SiO2)

Banded iron formation (ironstone)

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

Milky or Iron-Stained Quartz

Quartz (Silicon Dioxide, SiO2)

Orange Calcite

Calcium Carbonate (CaCO3)

Chert (River Pebble with Liesegang Rings)

Microcrystalline Silicon Dioxide (SiO2)

Likely calcite specimen

Calcite, calcium carbonate (CaCO₃)

Quartz Druzy / Quartz Crystal Cluster

Silicon Dioxide (SiO2)

Weathered limestone pebble

Calcite-rich limestone (primarily CaCO₃)

Jasper

Microcrystalline quartz, SiO2

Banded Jasper with Hematite or Quartz

Silicon Dioxide (SiO2) with impurities

Quartz Geode with Chalcedony

Silicon Dioxide (SiO2)

Blue apatite (likely dyed or enhanced)

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

Honey-colored calcite

Calcite (calcium carbonate, CaCO₃), likely rough or partly polished

Banded Iron Formation (Fragment)

Banded Iron Formation (BIF)