Banded iron formation fragment (likely hematite–magnetite ironstone)
Banded iron formation; chiefly hematite (Fe₂O₃), magnetite (Fe₃O₄), and microcrystalline quartz (SiO₂)
sedimentary
Category
Sedimentary (Chemically Precipitated) Or Metamorphic
Browse sedimentary (chemically precipitated) or metamorphic specimens identified by the Rock Identifier community.
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Quartz (Common or Milky Quartz)
Silicon Dioxide (SiO2)
mineral
Quartz (Smoky/Milky variety)
Silicon Dioxide (SiO2)
mineral
Quartzite with Sandstone/Iron staining
Metamorphic Quartzite (SiO2)
metamorphic
Milky quartz
Quartz (silicon dioxide, SiO₂), likely a massive vein-quartz specimen
mineral
Quartz-rich rock fragment
Milky quartz, primarily silicon dioxide (SiO₂), possibly quartzite or a feldspar-bearing vein rock
mineral
Banded Iron Formation
Banded Iron Formation (BIF)
sedimentary
Quartzite River Stone
Metamorphosed Quartz-rich Sandstone (SiO2)
metamorphic
Jasper with Quartz Vein
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Flint)
SiO2 (Microcrystalline Quartz)
sedimentary
Red Jasper
SiO2 (Microcrystalline Quartz)
sedimentary
Orange Calcite
Calcium Carbonate (CaCO3)
mineral
Quartz-encrusted Matrix
Silicon Dioxide (SiO2) with Ferruginous Sandstone
sedimentary
Milky quartz pebble
Quartz, silicon dioxide (SiO₂)
mineral
Sandstone (Ferruginous Concretion)
Arenite (with iron oxide cement)
sedimentary
Weathered limestone
Calcite-rich limestone (primarily CaCO₃)
sedimentary
Chert (with Manganese Dendrites)
Chert (Cryptocrystalline Quartz, SiO2)
sedimentary
Chert Nodule / Flint
Microcrystalline Quartz (SiO2)
sedimentary
Chert (and Flint)
Silicon Dioxide (SiO2)
sedimentary
Orange Calcite
Calcium Carbonate (CaCO3)
mineral
Limonite (Iron Ore)
Limonite (Iron oxide-hydroxide mixture, FeO(OH)·nH2O)
mineral
Orange Calcite
Calcium Carbonate (CaCO3)
mineral
Quartz
Silicon Dioxide (SiO2)
mineral
Quartzite Pebble
Quartzite
metamorphic
Quartz
Silicon Dioxide (SiO2)
mineral
Banded Iron Formation (BIF) with Quartz
Banded Iron Formation, often composed of alternating layers of hematite (Fe2O3) or magnetite (Fe3O4) and chert (microcrystalline quartz, SiO2)
Sedimentary
Milky quartz (likely quartz-rich rock)
Quartz, silicon dioxide (SiO₂)
mineral
Tumbled milky quartz
Quartz (silicon dioxide, SiO₂)
mineral
Tumbled milky quartz pebble
Quartz, silicon dioxide (SiO₂), microcrystalline to coarsely crystalline variety
mineral
Quartzite
Quartzite (SiO2)
metamorphic
Chert (River Pebble)
Chert (Cryptocrystalline Quartz, SiO2)
sedimentary
Banded Calcite (often sold as 'Mexican Onyx' or 'Green Onyx')
Calcite (Calcium Carbonate, CaCO3)
sedimentary
Yellow Jasper / Chert
Silicon Dioxide (SiO2) with Goethite or Limonite inclusions
sedimentary
Limestone
Calcium carbonate (CaCO3) / Limestone
sedimentary
Jasper (likely Polychrome or Mookaite variants)
Silicon Dioxide (SiO2) with iron oxide and hydroxide inclusions
sedimentary (chemically precipitated)
Slate
Slate (Metamorphic Rock)
metamorphic
Blue Calcite
Calcium Carbonate (CaCO3)
mineral
Aragonite Star Cluster
Aragonite (Calcium Carbonate, CaCO3)
mineral
Chert (Nodular)
Microcrystalline Quartz (SiO2)
sedimentary
Quartz Geode (Cracked Open Fragment)
Silicon Dioxide (SiO2)
mineral
Quartz Vein Pebble
Silicon dioxide (SiO2)
metamorphic
Quartz
Silicon Dioxide (SiO2)
mineral