Sedimentary (Chemically Precipitated)

Polished blue calcite

Calcite (CaCO₃), likely blue banded or massive calcite

Limestone Pebble

Calcite-rich Sedimentary Rock (CaCO3)

Honey calcite (orange calcite)

Calcite, calcium carbonate (CaCO₃)

Ironstone concretion

Iron-oxide-rich concretion, chiefly goethite (FeO(OH)) and/or hematite (Fe₂O₃) cementing sediment

Ironstone pebble (likely limonite/goethite-rich)

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

Quartz with Host Rock

SiO2 (Quartz) with fine-grained Matrix

Banded Iron Formation (BIF)

Banded Iron Formation (Taconite/Itabirite)

Oolitic Chert

Silicon Dioxide (SiO2) with oolitic texture

Small pale-yellow crystal, possibly calcite

Calcite (CaCO₃), tentative identification from the image

Tumbled quartz-rich stone, likely marble or calcite

Calcite (CaCO₃), possibly marble

Hematite

Hematite (Fe2O3)

Likely pale green calcite

Calcite (calcium carbonate, CaCO₃)

Red calcite

Calcite (CaCO₃), likely iron- or manganese-colored

Jasper

Microcrystalline Quartz (SiO2) with iron oxide impurities

Quartz and Mixed Sedimentary Rocks

Silicon Dioxide (SiO2) mixed with various clastic sedimentary lithologies

Calcite crystal cluster

Calcite (calcium carbonate, CaCO₃)

Banded Chert

Chert (Silicon Dioxide, SiO2)

Tumbled honey calcite

Calcite (calcium carbonate, CaCO₃)

Tumbled yellow calcite

Calcite (CaCO₃), likely honey/yellow calcite

Banded iron formation (iron-rich jasper/chert)

Banded iron formation, composed mainly of hematite–magnetite with microcrystalline quartz (jasper/chert)

Quartz Geode

Silicon Dioxide (SiO2) in Geode form

Quartz Pebble

Silicon Dioxide (SiO2)

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 Ochre / Limonite

Limonite (FeO(OH)·nH2O)

Banded Calcite (Mexican Onyx)

Calcium Carbonate (CaCO3)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Rhodochrosite

Manganese carbonate (MnCO3)

Pyrite nodule (probable iron sulfide concretion)

Pyrite, FeS₂, likely weathered within a sedimentary concretion

Orange Calcite

Calcite (Calcium Carbonate, CaCO3)

Orange Calcite

Calcite (Calcium Carbonate - CaCO3)

Green Calcite

Calcium Carbonate (CaCO3)

Orange Calcite

Calcium Carbonate (CaCO3)

Yellow Calcite

Calcium Carbonate (CaCO3)

Dark flint or chert fragment

Microcrystalline quartz (SiO₂), likely chert/flint

Chert / Flint

Microcrystalline Quartz (SiO2)

Honey calcite (calcareous mineral specimen)

Calcite, CaCO₃; likely honey/yellow calcite with minor iron-oxide staining

Likely chert/flint fragment

Microcrystalline quartz (SiO₂), possibly partially weathered chert

Quartz-veined Sandstone

Sedimentary rock with quartz vein (SiO2)

Calcite

Calcite (CaCO₃), likely crystalline limestone or marble fragment

Iron-rich concretion or weathered ironstone pebble

Goethite–hematite-bearing limonite concretion (tentative)

Chert (Flint Nodules)

Silicon Dioxide (SiO2)

Red Jasper with Quartz Veining

Silicon Dioxide (SiO2) with Hematite impurities