Pyrite
Iron Disulfide (FeS2)
Category
Browse organic (non geological) specimens identified by the Rock Identifier community.
Pyrite
Iron Disulfide (FeS2)
Black Tourmaline (Schorl)
Sodium Iron Aluminum Borosilicate (NaFe2+3Al6(BO3)3Si6O18(OH)4)
Black Obsidian
Volcanic Glass (felsic)
Obsidian
Volcanic Glass (SiO2 + impurities)
Obsidian
Obsidian (Volcanic Glass)
Petrified Wood
Siliconized Wood (SiO2)
Obsidian
Volcanic glass (SiO2 - Silicon dioxide predominant composition)
Quartzite
Metamorphic Quartz Rock (SiO2)
Fossil Bivalve / Ostreid Shell (Hag Stone / Perforated Pebble)
Phylum Mollusca, Class Bivalvia
Obsidian
Amorphous volcanic glass (70-75% SiO2)
Slag (Industrial Byproduct)
Ferrous/Non-ferrous Silicate
Quartzite
Quartzite (Primary mineral: SiO2)
Obsidian
Obsidian (Volcanic Glass, SiO2)
Shale
Shale (composition varies: primarily clay minerals and quartz)
Obsidian Arrowhead
Volcanic Glass (predominantly SiO2)
Obsidian
Volcanic Glass (Amorphous SiO2-rich glass)
Black Obsidian
Obsidian (Volcanic Glass)
Drill Core Sample
Cylindrical Rock Core (Specific mineralogy varies by extraction site)
Flint with Fossil Inclusion
Cryptocrystalline quartz (SiO2) enclosing fossilized organic remains
Chert Nodules in Limestone
Cryptocrystalline Quartz (SiO2) within Calcium Carbonate (CaCO3)
Glass Nugget (Tumbled Glass)
Amorphous Silicon Dioxide (SiO2) with additives
Black Obsidian
Obsidian (Volcanic glass), 70–75% SiO2
Petrified Wood
Silicified Wood (SiO2)
Quartzite Pebble
Metamorphic Quartzite
Blue Slag Glass
Ferro-silicate glass (Slag)
Grey Quartzite Pebble
Quartzite (primarily SiO2)
Obsidian (Apache Tear)
Volcanic Glass (Amorphous Silicon Dioxide, SiO2)
Polished Black Obsidian
Volcanic Glass (70-75% SiO2)
Obsidian
Volcanic Glass (SiO2)
Jasper
Microcrystalline Quartz (SiO2)
Limestone
Calcium Carbonate (CaCO3)
Limestone with Chert Nodule
Carbonate rock (CaCO3) with Microcrystalline Silicon Dioxide (SiO2) inclusion
Petrified Wood
Silicified Wood (primarily SiO2)
Obsidian
Volcanic Glass (70-75% SiO2)
Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
Snowflake Obsidian
Spherulitic Obsidian (Amorphous volcanic glass with Phenocrysts of Cristobalite)
Petrified Wood / Red Jasper
Silicified wood (primarily Silicon Dioxide, SiO2)
Weathered agate or chalcedony nodule
Microcrystalline quartz (SiO₂), likely agate/chalcedony with iron-oxide staining
Limestone
Calcium carbonate (CaCO3)
Chert / Flint
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Chert Nodule in Limestone
Microcrystalline Quartz (SiO2) within Calcium Carbonate (CaCO3)
Petrified Wood
Silicified Wood (primarily SiO2)