Ironstone (likely siderite or goethite-rich siltstone)
Ferruginous Siltstone
Category
Browse sedimentary (secondary mineral formation) specimens identified by the Rock Identifier community.
Ironstone (likely siderite or goethite-rich siltstone)
Ferruginous Siltstone
Red Jasper
Silicon Dioxide (SiO2) with iron oxide inclusions
Mixed Tumbled Stones Collection
Mixed Silicates and Carbonates (Quartz, Amorphous Silica, Carbonates)
Chalk (Calcitic)
Calcium Carbonate (CaCO3) - Biogenic Sedimentary Rock
Halite
Halite (Sodium Chloride, NaCl)
Apatite
Apatite Group (e.g., Fluorapatite Ca5(PO4)3F, Chlorapatite Ca5(PO4)3Cl, Hydroxylapatite Ca5(PO4)3(OH))
Quartz
Quartz (SiO₂ - Silicon Dioxide)
Sandstone (Quartzose Sandstone)
Clastic sedimentary rock (primarily SiO2)
Azurite and Malachite on Matrix
Cu3(CO3)2(OH)2 (Azurite) and Cu2CO3(OH)2 (Malachite)
Limestone
Calcium Carbonate (CaCO3)
Turquoise (with Hematite)
CuAl6(PO4)4(OH)8·4H2O
Limonite (Ironstone)
Hydrous ferric oxides (FeO(OH)·nH2O)
Yellow Chert (Jasper)
Microcrystalline Quartz (SiO2)
Sandstone
Arenite
Chert (often called Flint when dark or found in chalk)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Unidentified Rock Fragment
Unknown
Sandstone (Quartzose)
Arenite (Siliciclastic sedimentary rock)
Banded Iron Formation (BIF)
Banded Iron Formation (Fe2O3 + SiO2)
Chert (varieties include Flint and Jasper)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
Stromatolite (Jasper-replaced)
Fossilized Stromatolite (Cyanobacteria / Cryptozon / Silica SiO2)
Quartz Crystal
Quartz (SiO₂)
Diamond (in jewelry)
Carbon (C)
Chert (Flint variety)
Chert (SiO2)
Chert (Iron-stained)
Chert (Cryptocrystalline Quartz, SiO2)
Sandstone (Ferruginous)
Arenite (with Iron Oxide cement)
Chert (with Lichen)
Microcrystalline Quartz (SiO2)
Travertine
Calcareous Tufa / Travertine (CaCO3)
Concretion (Sandstone)
Carbonate-cemented Sandstone Concretion
Hematite
Hematite (Fe2O3)
Knightia Fossil in Limestone
Knightia eocaena in micritic limestone
Kambaba Jasper (Crocodile Jasper)
Stromatolite (Fossilized Algae within Microcrystalline Quartz), SiO2
Sandstone (Ferruginous)
Arenite (primarily SiO2 with iron oxide cement)
Sandstone (Ferruginous)
Arenite (primarily SiO2 with iron oxide cement)
Red Siltstone
Siltstone (primarily quartz and feldspar sized 0.0039 to 0.0625 mm)
Ironstone Concretion
Siderite or Hematite-bonded Concretion
River Rock / Stream Pebble
Fluvial Clast / Rounded Sedimentary Particle
Limestone
Calcium Carbonate (CaCO3)
Conglomerate (Red Sandstone variety)
Clastic Sedimentary Rock (Conglomeratic Sandstone)
Sandstone
Arenite (primarily SiO2)
Sandstone (Quartzite Pebble)
Arenite / Metamorphosed Sandstone (SiO2)
Jasper (likely Polychrome or Ocean Jasper)
Silicon Dioxide (SiO2) with impurities
Limonite (Iron Ore)
Limonite (FeO(OH)·nH2O)