Ferruginous Sandstone (Ironstone)
Clastic sedimentary rock (SiO2 with Fe2O3/FeO(OH) cement)
sedimentary
Category
Biogenic Material
Browse biogenic material specimens identified by the Rock Identifier community.
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Diamond
Carbon (C)
mineral
Coquina
Bioclastic Limestone (composed primarily of Calcium Carbonate / CaCO3)
sedimentary
Limonite Concretion (Goonie or Rattlestone)
Limonite (FeO(OH)·nH2O)
sedimentary
Chert (Black Chert/Flint)
Silicon Dioxide (SiO2)
sedimentary
Chert (Nodule)
Silicon Dioxide (SiO2)
sedimentary
Chert (and Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (often called Flint or Jasper when pigmented)
Microcrystalline or cryptocrystalline Quartz (SiO2)
sedimentary
Green Chert (Jasper)
Silicon Dioxide (SiO2)
sedimentary
Chert (Jasper/Flint variety)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Iron Meteorite
Iron Meteorite (primarily Kamacite and Taenite, Fe-Ni alloys)
mineral
Carborundum
Silicon Carbide (SiC)
mineral
Banded Calcite (often sold as Onyx or Mexican Onyx)
Calcite (Calcium Carbonate, CaCO3)
sedimentary
Fossilized Bone Fragment
Vertebrate Fossil Material (Apatite/Calcium Phosphate)
fossil
Polished pink feldspar or quartz pebble (uncertain)
Likely microcline feldspar (KAlSi₃O₈) or quartz (SiO₂), with iron-oxide inclusions
mineral
Tumbled prehnite (probable)
Prehnite — Ca₂Al(AlSi₃O₁₀)(OH)₂
mineral
Polished brown stone, likely smoky quartz or jasper
Tentatively quartz (SiO₂), possibly smoky quartz; exact identification requires testing
mineral
Small pale mineral fragment
Unidentified; possibly quartz, calcite, or feldspar
mineral
Tumbled tan pebble, likely sandstone or chert
Uncertain; probable quartz-rich sandstone (SiO₂-bearing)
sedimentary
Tumbled citrine or iron-stained quartz
Quartz (SiO₂), likely iron-oxide-stained or natural citrine
mineral
Quartz geode
Microcrystalline quartz and drusy quartz (SiO₂), commonly lining a chalcedony-rich cavity
mineral
Flint (chert), possibly fossil-bearing
Microcrystalline quartz (SiO₂), chalcedony/flint variety
sedimentary
Rounded dark river pebble
Likely fine-grained basalt or andesite; exact identification requires a fresh surface or tests
sedimentary
Raw green aventurine (likely quartzite)
Quartz-rich quartzite, chiefly microcrystalline SiO₂ with green mica/fuchsite or chlorite
metamorphic
Tumbled quartz pebble
Quartz (SiO₂), likely milky or fractured rock crystal
mineral
Banded sandstone pebble
Lithic or quartz-rich sandstone; exact composition requires testing
sedimentary
Amethyst-bearing quartz (rough/tumbled fragment)
Quartz, SiO₂; purple coloration from irradiation and trace iron
mineral
Iron meteorite fragment
Fe-Ni meteorite, likely an iron meteorite or stony-iron fragment
meteorite
Milky quartz
Quartz (SiO₂), commonly massive or vein quartz
mineral
Quartzite
Metamorphic Quartzite (SiO2)
metamorphic
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Limestone
Sedimentary Rock (Primarily CaCO3)
sedimentary
Quartzite
Metamorphic Quartz Rock (SiO2)
metamorphic
Quartzite
Metamorphic Quartzite (SiO2)
metamorphic
Limestone
Sedimentary Rock (Primarily CaCO3)
sedimentary
Quartzite
Metamorphic Quartzite (SiO2)
metamorphic
Quartzite
Metamorphic Quartzite (SiO2)
metamorphic
Sandstone
Sedimentary Rock (Quartz arenite)
sedimentary
Carnelian
Quartz (Silicon Dioxide, SiO2)
gemstone
Banded Iron Formation
Banded Iron Formation (BIF)
sedimentary
Quartzite
Metamorphic Quartz (SiO2)
metamorphic