Gneiss
High-grade metamorphic rock (Gneiss)
metamorphic
Category
Organic Structure (Not A Rock)
Browse organic structure (not a rock) specimens identified by the Rock Identifier community.
Milky Quartz (Quartz Vein)
Silicon Dioxide (SiO2)
mineral
Moonstone
Orthoclase Feldspar (KAlSi3O8)
mineral
Sandstone (Graywacke)
Clastic Sedimentary Rock (Lithic Sandstone)
sedimentary
Yellow Quartzite
Quartzite (SiO2 with iron oxide inclusions)
metamorphic
Fossiliferous Chert with Brachiopod Impression
Chert (SiO2) containing Brachiopoda fossil remains
sedimentary
Agate
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Shale
Fissile mudrock (composed of clay-sized particles and detrital grains)
sedimentary
Biotite (Black Mica)
Biotite - K(Mg,Fe)3AlSi3O10(F,OH)2
mineral
Yellow Chert or Jasper
Microcrystalline Quartz (SiO2)
sedimentary
Peridotite (Pyroxenite/Serpentinized Dunite)
Ultramafic Rock (consisting primarily of Olivine and Pyroxene)
igneous
Chert Breccia (Yellow Jasper)
Silicon Dioxide (SiO2) - Brecciated Chert
sedimentary
Chert (Jasper/Flint variety)
Microcrystalline silicon dioxide (SiO2)
sedimentary
Chert (Flint)
Silicon Dioxide (SiO2)
sedimentary
Petrified Wood
Silicified wood (principally Silicon Dioxide, SiO2)
sedimentary
Banded Chert
Cryptocrystalline Quartz (SiO2)
sedimentary
Chert (Iron-stained)
Chert (primarily Microcrystalline Quartz, SiO2)
sedimentary
Chert (Red/Pink Jasper subtype)
Silicon Dioxide (SiO2)
sedimentary
Petrified Wood
Silicified Wood (SiO2 permineralization)
sedimentary
Amber
Succinite (fossilized resin)
mineral
Black Marble
Recrystallized Calcite (CaCO3)
metamorphic
River Pebble (Quartz/Jasper)
Silicon Dioxide (SiO2)
sedimentary
Jasper (Brown Iron-Rich Variety)
Silicon Dioxide (SiO2) with Fe2O3 (Iron Oxide/Crystalline Quartz)
sedimentary
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Chert (specifically Chalcedony/Flint variant)
Silicon Dioxide (SiO2)
sedimentary
Chert (with Quartz Veining)
Chert (formula: SiO2)
sedimentary
Agate Geode
Silicon Dioxide (SiO2) - Chalcedony / Quartz Variety
Mineral
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Pink Opal / Peruvian Opal
Hydrated amorphous silicon dioxide (SiO2·nH2O)
Mineral
Milky Quartz
Quartz (Silica / Silicon Dioxide), SiO2
mineral
Chert (variously known as Flint or Jasper)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Fossilized Wood (Petrified Wood)
Silicified Wood (primarily quartz/chalcedony replacing organic matter)
Sedimentary (with some aspects of mineral replacement)
Bauxite / Iron-rich Laterite
Laterite (principally Al(OH)3, Fe2O3, and SiO2)
sedimentary
Desert Varnish on Sandstone
Ferromanganese coating on Quartz Arenite
sedimentary
Banded Chert (Flint/Jasper variety)
Microcrystalline Quartz (SiO2)
sedimentary
Water and Silt (Sedimentary Environment)
Suspended Sediment / H2O (dihydrogen monoxide)
sedimentary
Diamond in Kimberlite
Kimberlite host rock with C (Carbon) inclusion
igneous
Quartz Vein in Host Rock
Silicon Dioxide (SiO2)
mineral with metamorphic or sedimentary host
Granite
Phaneritic Plutonic Felsic Rock
igneous
Geode (Unopened)
Siliceous Concretion / Geode
sedimentary
Serpentinite
Serpentinite (composed primarily of Serpentine group minerals, Mg3Si2O5(OH)4)
metamorphic
Wood Beads (Palmwood/Ebony)
Various species for wood, but often refers to woods like Palmwood (e.g., Borassus flabellifer) or Ebony (Diospyros spp.) for their distinctive grain and hardness.
Organic Gem Material (Botanical)