Geode (Chert or Quartz Nodule)
Silicon Dioxide (SiO2)
Category
Browse the purple specimen is a mineral (amethyst); the white specimen is a sedimentary rock (limestone or marble). specimens identified by the Rock Identifier community.
Geode (Chert or Quartz Nodule)
Silicon Dioxide (SiO2)
Rough Quartz (with potential Host Rock)
Silicon Dioxide (SiO2)
Limonitic Sandstone with Inclusion
Limonitic Quartz Sandstone (primarily SiO2 with FeO(OH)·nH2O)
Chert (Jasper/Agate variety)
Cryptocrystalline Quartz (SiO2)
Quartz (likely) / Siliceous rock with quartz phenocrysts (if a rock fragment)
Quartz (SiO₂)
Citrine (Iron-stained Quartz)
Silicon Dioxide (SiO2)
Quartzite Pebbler
Quartzite (primarily SiO2)
Quartzite (River Cobble)
Metamorphosed Quartz Sandstone (SiO2)
Travertine (used in construction, not a 'specimen' in situ)
Travertine
Quartz
Quartz (SiO2 - Silicon Dioxide)
Fossiliferous Chert with Brachiopod Impression
Chert (SiO2) containing Brachiopoda fossil remains
Amethyst
Quartz variety; chemical formula: SiO₂ (silicon dioxide) with Fe³⁺ impurities
Lapis Lazuli
Lapis Lazuli (a rock composed primarily of Lazurite (Na,Ca)8(AlSiO4)6(S,SO4,Cl)1-2, with varying amounts of Calcite, Pyrite, and Sodalite).
Jasper Marble
Silicon Dioxide (SiO2) with Impurities
Amethyst
Silicon Dioxide (SiO2) with trace Iron impurities
Oolitic Chert
Ooidal Microcrystalline Quartz (SiO2)
Clear/White Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
Amethyst
Silicon Dioxide (SiO2) with Fe3+ impurities
Amethyst (Chevron or Banded Amethyst)
Silicon Dioxide (SiO2) with Fe3+ impurities
Satin Spar (Gypsum)
Hydrous Calcium Sulfate (CaSO4·2H2O)
Oyster Shell (Aragonite/Calcite)
Calcium Carbonate (CaCO3)
Quartz (various varieties)
SiO₂ (Silicon Dioxide)
Quartz Vein in Siltstone
SiO2 (Quartz) on clastic sedimentary matrix
Quartzite Pebble (River Rock)
Quartzite (SiO2)
White Marble (Industrial/Architectural)
Recrystallized Calcite (CaCO3)
Amethyst
Silicon Dioxide (SiO2) with iron impurities
Chert (Brecciated or Veined)
Silicon Dioxide (SiO2)
Pink Amethyst Geode
Silicon Dioxide (SiO2) with Hematite/Iron impurities
Chert (and/or Chalcedony)
Silicon dioxide (SiO2)
Blue Calcite
Calcium Carbonate (CaCO3)
Quartz (Engineered Stone Countertop)
Silicon Dioxide (SiO2) within a resin matrix
Rough Quartz (or Quartzite pebble)
Silicon Dioxide (SiO2)
Chevron Amethyst
Silicon Dioxide (SiO2) with trace Iron (Fe3+)
Orange Calcite
Calcium Carbonate (CaCO3)
Quartz
Silicon Dioxide (SiO₂)
Coquina
Biogenic Limestone (Calcium Carbonate, CaCO3)
Fossiliferous Limestone
Fossiliferous Limestone (CaCO3)
Quartz Geode
Silicon Dioxide (SiO2)
Mookaite Jasper
Silicon Dioxide (SiO2) with iron oxide impurities
Picasso Jasper (or Picasso Marble)
Metamorphosed Limestone (Calcium Carbonate, CaCO3, with impurities)
Amethyst and Hematite Bracelet
Amethyst (SiO2) and Hematite (Fe2O3)
Chert (Jasper)
Microcrystalline Quartz (SiO2)