Pyrite in Shale
Iron Disulfide (FeS2)
mineral
Category
Sedimentary (Volcanic)
Browse sedimentary (volcanic) specimens identified by the Rock Identifier community.
Mahogany Obsidian
Volcanic Glass with Hematite or Magnetite inclusions (SiO2 + Fe2O3)
igneous
Sandstone
Clastic Sedimentary Rock (composed mostly of SiO2)
sedimentary
Fire Agate
SiO2 (Silicon Dioxide with Iron Oxide inclusions)
mineral
Crazy Lace Agate
Silicon Dioxide (SiO2) with impurities
mineral
Blue Lace Agate
Silicon Dioxide (SiO₂)
Mineral (Variety of Chalcedony/Quartz)
Flowerstone (Porphyry)
Porphyritic Andesite or Basalt
igneous
Sandstone (with carbonaceous plant fragments)
Arenite (composed primarily of SiO2)
sedimentary
Sandstone
Arenite (primarily composed of SiO2)
sedimentary
Shale
Fissile Siliciclastic Sedimentary Rock
sedimentary
Pumice
Pumice (a highly vesicular volcanic rock)
igneous
Vesicular Basalt (or Scoria)
Vesicular Basalt
igneous
Basalt (River-worn Specimen)
Extrusive Mafic Igneous Rock
igneous
Orange Calcite
Calcite (Calcium Carbonate, CaCO3)
mineral
Basalt
Mafic Igneous Rock (primarily Plagioclase Feldspar and Pyroxene)
igneous
Chalcedony or Chert/Jasper with secondary mineral staining
SiO2 (for chalcedony/quartz) with possible secondary copper minerals (e.g., CuSiO3·nH2O for chrysocolla, Cu2(CO3)(OH)2 for malachite) or iron oxides/hydroxides.
Mineral, potentially a rock with chalcedony/jasper.
Blue Lace Agate
Chalcedony (SiO2) with trace inclusions
mineral
Basalt with Quartz/Plagioclase Inclusions
Mafic volcanic rock (Basaltic)
igneous
Chert
Silicon dioxide (SiO2)
sedimentary
Basalt
Basalt (Aphanitic Mafic Volcanic Rock)
igneous
Agate (or Chalcedony)
SiO2 (Silicon Dioxide) - a cryptocrystalline variety of quartz
Mineral
Red Jasper (possibly)
Jasper (a variety of Chalcedony, SiO2)
Mineral
Basalt
Basalt (Mafic volcanic rock)
igneous
Amethyst and Limestone
Amethyst (SiO2 - Silicon Dioxide) and Limestone (CaCO3 - Calcium Carbonate)
The purple specimen is a mineral (Amethyst); the white specimen is a sedimentary rock (Limestone or Marble).
Jasper (likely a variety of Yellow or Mustard Jasper)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary (chemically precipitated mineral)
Rhyolite
Rhyolite (Extrusive Igneous Rock)
igneous
Andesite
Andesite (contains Plagioclase feldspar, Pyroxene, Hornblende)
igneous
Porphyritic Andesite
Porphyritic Andesite (Intermediate Volcanic Rock)
igneous
Olivine in Basalt (Peridot)
Magnesium Iron Silicate (Mg, Fe)2SiO4 in Vesicular Basalt
igneous
Obsidian
Vitreous volcanic silicate (70-75% SiO2)
igneous
Snowflake Obsidian (or similar porphyritic volcanic rock)
Obsidian with Spherulites (if glassy), or Porphyritic Rhyolite/Andesite (if crystalline groundmass)
igneous
Scoria
Vesicular Basalt / Scoria
igneous
Scoria
Scoria (Vesicular Basalt)
igneous
Porphyritic Rhyolite (Cookie Stone)
Porphyritic Rhyolite (SiO2, with phenocrysts)
igneous
Amethyst
Amethyst (Silicon Dioxide, SiO2)
mineral
Sandstone (Ferruginous)
Arenite (primarily SiO2 with Iron Oxide cement)
sedimentary
Sandstone (Ferruginous)
Arenite (Fe-oxide cemented)
sedimentary
Shale
Fissile Mudstone
sedimentary
Sandstone (Ferruginous)
Clastic Sedimentary Rock (SiO2 with Fe2O3/FeOOH cement)
sedimentary
Gastropod Steinkern (Internal Mold Fossil)
Gastropoda (Class); Internal mold or 'Steinkern' composed of Calcium Carbonate (CaCO3) or Sedimentary matrix
sedimentary
Basalt
Extrusive mafic volcanic rock
igneous
Basalt
Basalt (Mafic volcanic rock)
igneous