Agate
Silicon dioxide (Chalcedony), SiO2
gemstone
Category
Mixed: Igneous And Sedimentary
Browse mixed: igneous and sedimentary specimens identified by the Rock Identifier community.
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Agate
Silicon Dioxide (Chalcedony), SiO2
sedimentary
Black Tourmaline
Schorl (Na(Fe²⁺)₃Al₆(BO₃)₃Si₆O₁₈(OH)₄)
mineral
Greywacke (River Pebble)
Greywacke sandstone with quartz veining
sedimentary
Mixed river pebbles and quartz-rich specimens
Polymictic fluvial gravel; likely quartz, quartzite, chert, and weathered feldspathic rocks
sedimentary
White Agate / Chalcedony
Silicon Dioxide (SiO2)
gemstone
Rhodonite
Manganese Silicate (Mn,Fe,Mg,Ca)SiO3
mineral
Mixed River Pebbles (Jasper, Hematite, and Quartzites)
Silicon dioxide (Jasper/Quartz) and Iron oxide (Hematite)
sedimentary
Mixed River Pebbles and Rock Collection
Polymictic lithic conglomerate, sandstone, and quartz pebbles
sedimentary
Mixed rounded fieldstones, likely granite and gneiss
Granite (quartz–feldspar–mica) and gneiss; exact identification is uncertain from the photograph
igneous and metamorphic
Mixed Tumbled Stones Collection
Mixed Silicates and Carbonates (Quartz, Amorphous Silica, Carbonates)
multiple
Pyrite and Calcite (or Barite) Specimen
Iron Sulfide (FeS2) with Calcium Carbonate (CaCO3)
mineral
Tumbled hematite (likely hematite-rich ironstone)
Hematite, Fe₂O₃; possibly mixed with magnetite or goethite
mineral
Chalcedony (Agate)
Silicon Dioxide (SiO2)
mineral
Agate
Silicon Dioxide (Chalcedony), SiO2
mineral
Garnet (likely Almandine, Pyrope, or a blend)
Garnet group minerals: X3Y2(SiO4)3, where X and Y represent various metal ions (e.g., Almandine: Fe3Al2(SiO4)3, Pyrope: Mg3Al2(SiO4)3)
Mineral
Weathered quartzite cobble
Quartzite, predominantly crystalline SiO₂
metamorphic
Carnelian Agate
Cryptocrystalline Quartz (SiO2) with Iron Oxide impurities
mineral
Yellow Chalcedony
Silicon Dioxide (SiO2)
mineral
River Pebbles and Cobbles
Mixed Siliciclastic Sediments (Quartzite, Chert, and Sandstone clasts)
sedimentary
Banded Iron Formation (BIF) / Iron Ore
Hematite-Magnetite BIF (Fe2O3 / Fe3O4 mixed with SiO2)
sedimentary
Mixed Mineral and Fossil Collection
Multi-specimen assemblage (SiO2, CaCO3, FeS2, etc.)
mineral
Concrete with Exposed Aggregate
Anthropogenic conglomerate (Concrete)
man-made rock (sedimentary analogue)
Pyrite (locally known as Fool's Gold)
Iron Sulfide (FeS2)
mineral
Pumice
Vesicular volcanic glass (Amorphous silica mixed with various oxides)
igneous
Limonite (Iron Ore/Sandstone mixture)
Limonite (FeO(OH)·nH2O) often mixed with Goethite and sedimentary matrix
mineral
Epidosite (Epidote-rich rock)
Epidosite (consisting primarily of Epidote: {Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH))
metamorphic
Metallic sulfide mineral specimen, likely pyrite
Pyrite (FeS₂), possibly a pyrite-rich sulfide aggregate
mineral
Red Jasper (in Quartz/Chalcedony)
Silicon Dioxide (SiO2) with iron oxide inclusions
sedimentary
Jasper pebble (possibly Red Jasper or Lake Superior Agate/Jasper mix)
Silicon Dioxide (SiO2) with Hematite inclusions
sedimentary
Granite
Granite (composed of quartz, potassium feldspar, plagioclase, and mica/biotite)
igneous
Lapis Lazuli
Lapis Lazuli (a rock composed primarily of Lazurite)
Metamorphic rock
Botryoidal hematite (iron-oxide specimen)
Hematite, Fe₂O₃; possibly mixed with goethite/limonite
mineral
Mixed Quartz and Jasper Pebbles
Silicon Dioxide (SiO2)
Mineral
Black Tourmaline
Schorl (Na(Fe²⁺)₃Al₆(BO₃)₃Si₆O₁₈(OH)₄)
Mineral
Agate
Silicon Dioxide (Chalcedony), SiO2
sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
sedimentary
Chalcedony (Agate and Carnelian varieties)
Silicon Dioxide (SiO2)
mineral
Tumbled Agate
Silicon Dioxide (Quartz variety: Chalcedony)
gemstone
Blue Agate Slice
Chalcedony (SiO2)
gemstone
Agate
Silicon dioxide (Chalcedony), SiO2
sedimentary
Agate
Chalcedony (SiO2)
mineral