Ironstone (iron-oxide-rich rock)
Ironstone, composed mainly of hematite (Fe₂O₃) and/or goethite (FeO(OH)); exact minerals cannot be confirmed visually
Category
Browse sedimentary (physico chemical precipitate) specimens identified by the Rock Identifier community.
Ironstone (iron-oxide-rich rock)
Ironstone, composed mainly of hematite (Fe₂O₃) and/or goethite (FeO(OH)); exact minerals cannot be confirmed visually
Banded Iron Formation (Fragment)
Banded Iron Formation (BIF)
Jasper
Silicon dioxide (SiO2) with iron impurities
Yellow Ocher (Limonite)
Limonite (Hydrated Iron Oxide) - FeO(OH)·nH2O
Orange Calcite (Polished Sphere)
Calcium Carbonate (CaCO3)
Red Jasper (River Pebble)
Silicon Dioxide (SiO2) with iron oxide inclusions
Chert
Microcrystalline Quartz (SiO2)
Blue calcite (probable)
Calcite — CaCO₃
Ferruginous Sandstone
Arenite with Iron-Oxide cement (Fe2O3 · nH2O)
Chert / Jasper
Silicon Dioxide (SiO2)
Flint
SiO2 (Microcrystalline Quartz / Chert)
Quartz pebble
Silicon Dioxide (SiO2)
Quartz
Silicon Dioxide (SiO2)
Chert (Jasper/Jasperoid)
Chert (chemically precipitated microcrystalline Quartz, SiO2)
Banded Calcite / Onyx Marble
Calcite (Travertine / Onyx Marble, CaCO3)
Orange Calcite
Calcium Carbonate (CaCO3)
Banded Calcite (Green Onyx)
Calcite (CaCO3)
Chert (Yellow Jasper/Flint)
Silicon Dioxide (SiO2)
Limestone
Sedimentary rock composed mainly of calcite (CaCO3)
Limonite (Ironstone)
Hydrated Iron(III) Oxide-hydroxide (FeO(OH)·nH2O)
Chert / Flint (with Crinoid Stem Molds)
Microcrystalline Quartz (SiO2)
Bumblebee Jasper
Travertine (Calcite/Aragonite) with Realgar, Pyrite, and Volcanic Ash
Calcite
Calcium Carbonate (CaCO3)
Pink calcite cluster
Calcite (calcium carbonate, CaCO₃)
Yellow Ochre / Limonite
Limonite (FeO(OH)·nH2O)
Quartz
Silicon Dioxide (SiO2)
Calcite crystal cluster
Calcite — calcium carbonate, CaCO₃
Honey calcite (orange calcite)
Calcite, calcium carbonate (CaCO₃)
Polished blue calcite
Calcite (CaCO₃), likely blue banded or massive calcite
Black Chert River Stone
Cryptocrystalline Quartz (SiO2)
Fairy Stone (Menilite Concretion)
Carbonate-rich concretion (often Siderite or Calcite in Clay)
Chert (Flint)
Microcrystalline Quartz (SiO2)
Limonite (Ironstone Concretion)
Limonite (Hydrous ferric oxide mixture, FeO(OH)·nH2O)
Chert (River Pebble with Liesegang Rings)
Microcrystalline Silicon Dioxide (SiO2)
Red calcite
Calcite (CaCO₃), likely iron- or manganese-colored
Honey Calcite
Calcium Carbonate (CaCO3)
Sandstone with Liesegang Rings
Arenite with Iron Oxide Concretions
Banded Jasper
Silicon Dioxide (SiO2) with iron oxide inclusions
Chert (with Quartz Veining)
Microcrystalline Quartz (SiO2)
Fossiliferous Limestone
Calcium Carbonate (CaCO3) with Biogenic Inclusions
Chert (Flint) Nodule
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Ironstone concretion
Iron-oxide-cemented sedimentary concretion, commonly hematite/goethite with quartz or clay