Bauxite
Alumina-rich rock (consisting of Gibbsite, Boehmite, and Diaspore)
Category
Browse sedimentary rock (specifically a clastic sedimentary rock formed into a cobble) specimens identified by the Rock Identifier community.
Bauxite
Alumina-rich rock (consisting of Gibbsite, Boehmite, and Diaspore)
Septarian Nodule (Dragon Stone) sphere
Septarian concretion (Calcite, Aragonite, and Limestone)
Quartz Geode Fragment
Silicon Dioxide (SiO2)
Amber
Succinite (specifically for Baltic Amber), Formula: C10H16O
Ironstone (with Limonite/Goethite)
Ferruginous Sedimentary Rock (contains Limonite FeO(OH)·nH2O and Hematite Fe2O3)
Gneiss
Gneiss (High-grade regional metamorphic rock)
Gneiss
Gneiss (High-grade regional metamorphic rock)
Moqui Marble (Moqui Ball)
Ironstone Concretion (Goethite/Hematite cemented Sandstone)
Chert (Hagstone/Adder Stone)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Chert (specifically Flint)
Microcrystalline Quartz (SiO2)
Belemnite Fossil (Guard)
Belemnoidea (Carbonate/Calcite replacement)
Septarian Nodule (Yellow Jasper variety)
Septarian Nodule (comprising Calcite, Aragonite, and Limestone/Bentonite)
Chert Pebble (with Quartz Vein)
Chert (Cryptocrystalline Silica - SiO2)
Pumice
Pumice (volcanic rock)
Chert
Chert (microcrystalline quartz)
Mica Schist
Mica Schist (predominantly Muscovite/Biotite)
Schist
Mica Schist (primarily Muscovite or Biotite sheet silicates)
Milky Quartz
Silicon Dioxide (SiO2)
Septarian Nodule
Septarian concretion (Complex mixture of Siderite/Limestone, Calcite, and Aragonite)
Mookaite (Mookaite Jasper)
Silicified Radiolarite (SiO2 with iron oxides)
Chert (specifically Flint Arrowhead)
Silicon dioxide (SiO2) - Microcrystalline Quartz
Chert (and/or River Pebble)
Microcrystalline quartz (SiO2)
Amethyst
Amethyst (Silicon Dioxide, SiO2)
Carnelian (Red Chalcedony)
Silicon Dioxide (SiO2)
Carnelian
Carnelian (subset of Chalcedony); SiO2 with Iron Oxide impurities
Opal
Hydrated Amorphous Silica (SiO2·nH2O)
Dolomite on Prehnite (Saddle-shaped Dolomite)
Dolomite [CaMg(CO3)2] on Prehnite [Ca2Al(AlSi3O10)(OH)2]
Jasper with Quartz inclusions
Silicon Dioxide (SiO2) with varying mineral impurities
Carnelian (a variety of Chalcedony)
Silicon Dioxide (SiO2) with iron oxide impurities
Opal
Hydrated Amorphous Silica (SiO2·nH2O)
Quartz Vein in Host Rock
Silicon Dioxide (SiO2) within Sedimentary or Igneous Matrix
Turquoise
Turquoise (Hydrated phosphate of copper and aluminium) - CuAl6(PO4)4(OH)8·4H2O
Chert (Iron-stained)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Carnelian Agate/Jasper blend
Silicon Dioxide (SiO2) - variety of Chalcedony
Chert (River Pebble)
Microcrystalline Quartz (SiO2)
Schist (specifically Mica Schist)
Mica Schist (primarily composed of Muscovite KAl2(AlSi3O10)(OH)2 and Biotite)
Wishing Stone (Basalt/Greywacke with Quartz Vein)
Basalt or Siltstone with SiO2 (Quartz) hydrothermal intrusion
Chert (Yellow Jasper/Flint)
Microcrystalline Quartz (SiO2)
Banded Gneiss
Gneiss (High-grade Regional Metamorphic Rock)
Clear Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
Porphyritic Basalt or Diabase with Plagioclase Phenocrysts
Porphyritic Basalt or Diabase; Mineral: Plagioclase Feldspar
Quartz Druzy on Matrix (likely Agate or Jasper)
Silicon Dioxide (SiO2) with various mineral inclusions