Ironstone Nodules in Chalk/Limestone
Limonite/Goethite concretions (FeO(OH)·nH2O) in Calcium Carbonate matrix (CaCO3)
sedimentary
Category
Organic (Non Rock)
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Shale
Shale (composition varies: primarily clay minerals and quartz)
sedimentary
Petrified Bone (Fossil Bone)
Per mineralization fossil bone (varies by organism, predominantly replacement by SiO2 - Quartz/Chalcedony)
fossil
Fossil Shell Fragment (possibly Brachiopod or Bivalve)
Calcium Carbonate (CaCO3) - Phylum Brachiopoda or Mollusca
sedimentary
Green Slag Glass
Cullet (Amorphous Silicon Dioxide with impurities)
Man-made rock-like material
Geode with Quartz Crystal Cavity
Silicon Dioxide (SiO2) in Calcareous/Siliceous Matrix
sedimentary
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Quartzite Pebble
Quartzite (SiO2)
metamorphic
Fossiliferous Rock (Invertebrate Fossil in Matrix)
Fossiliferous limestone or shaly matrix containing skeletal fossil remains
fossil
Gravel / Limestone Fragment
Calcium Carbonate (CaCO3) / Fine-grained Sedimentary Rock
sedimentary
Unakite
Epidotized Granite
metamorphic
Iron-stained weathered granite or granitic gneiss
Granite/granitic gneiss, dominated by quartz, feldspar, and mica, with iron-oxide weathering
igneous
Chert (Pebble)
Microcrystalline Quartz (SiO2)
sedimentary
Herkimer Diamond
Quartz (Silica - SiO2)
mineral
Quartzite Pebble
Metamorphosed Quartz Sandstone (SiO2)
metamorphic
Quartzite
Quartzite (SiO2)
metamorphic
Sandstone
Sandstone (SiO2 predominant)
sedimentary
Likely blue glass or synthetic gemstone jewelry
Uncertain; possibly synthetic spinel, cubic zirconia, or blue glass
gemstone
Tektite
Impactite (Natural Silicate Glass)
meteorite
White Marble
Metamorphic carbonate rock (primarily CaCO3)
metamorphic
Fossiliferous Limestone
Biogenic Limestone (Calcium Carbonate, CaCO3)
sedimentary
Quartzite Pebble
Quartzite
metamorphic
Obsidian
Obsidian (Amorphous volcanic glass)
igneous
Quartzite
Quartzite (SiO2)
metamorphic
Weathered metallic meteorite candidate
Unclassified meteorite; appearance possibly iron meteorite or stony-iron material
meteorite
Asphalt aggregate
Human-made bituminous asphalt containing crushed silicate rock aggregate
sedimentary
Rounded quartz-rich river cobble
Likely quartzite or quartz-rich sandstone (SiO₂-dominant), possibly weathered chert
sedimentary
Fossilized Brachiopod
Brachiopoda (Phylum)
fossil
Weathered polymictic gravel/conglomeratic rock
Polymictic conglomerate or poorly lithified alluvial gravel; chiefly quartz, feldspar, mica, and dark lithic fragments
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Quartzite Pebble
Quartzite (SiO2)
metamorphic
Banded Chert
Chert (Silicon Dioxide, SiO2)
sedimentary
Chert (Limestone/Flint variant)
Microcrystalline or cryptocrystalline Quartz (SiO2)
sedimentary
Red Jasper with Quartz
Microcrystalline Quartz (SiO2)
sedimentary
Chert (specifically Jasper/Brown Chert)
Silicon Dioxide (SiO2)
sedimentary
Chert (varieties include Flint and Jasper)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Jasper
Silicon dioxide (SiO2)
sedimentary
Chert with Calcite Veins
Silicon Dioxide (SiO2) with Calcium Carbonate (CaCO3) intrusions
sedimentary
Fossiliferous Limestone (Coquina)
Biogenic Limestone (Calcium Carbonate, CaCO3)
sedimentary
Fossilized Bone
Permineralized Vertebrate Bone
fossil
River Rock (Quartzite)
Quartzite (SiO2)
metamorphic
Coal
Bituminous coal (Complex organic sedimentary rock)
sedimentary