Chert (Gravel Bit)
Microcrystalline silica (SiO2)
Category
Browse antropogenic (man made glass byproduct) specimens identified by the Rock Identifier community.
Chert (Gravel Bit)
Microcrystalline silica (SiO2)
Grey Granite
Phaneritic Felsic Intrusive Igneous Rock
Marble
Marble (metamorphosed limestone/dolostone). Predominantly composed of Calcite (CaCO3) for marble derived from limestone, or Dolomite (CaMg(CO3)2) for marble derived from dolostone.
Serpentinite
Serpentinite (composed primarily of serpentine-group minerals like antigorite, chrysotile, and lizardite; chemical formula varies but generally Mg3Si2O5(OH)4)
Amethyst
Amethyst (Silicon Dioxide, SiO2 + Fe4+ impurities)
Amber (and Citrine Quartz)
Succinite (Amber) and Silicon Dioxide (SiO2)
Red Coral (Precious Coral)
Corallium rubrum (Calcium Carbonate, CaCO3)
Carnelian
Carnelian (a variety of Chalcedony, SiO2)
Stainless Steel Spoon
Iron-Chromium Alloy (Fe + Cr + Ni)
Flesh-colored Quartzite
Quartzite (SiO2)
Porphyritic Basalt or Diabase with Plagioclase Phenocrysts
Porphyritic Basalt or Diabase; Mineral: Plagioclase Feldspar
Snowflake Obsidian
Vitreous Volcanic Glass (Siliceous Obsidian with Cristobalite inclusions)
Turquoise
Turquoise (Hydrated copper aluminum phosphate, CuAl6(PO4)4(OH)8·4H2O)
Citrine Quartz
Silicon Dioxide (SiO2) with ferric iron impurities
Mahogany Obsidian
Obsidian (Volcanic Glass) with Hematite/Magnetite inclusions
Serpentine Schist with Quartz Vein
Serpentine Schist (a type of Metamorphic rock). The white band is likely Quartz (SiO2).
Granite
Granite (a felsic intrusive igneous rock)
Blue Chalcedony and Picture Jasper Beads
Blue Chalcedony (SiO2), Picture Jasper (SiO2)
Basalt (Lava Rock) and Dyed Glass/Quartz
Scoria (Vesicular Basalt)
Chalcedony (Banded/Mottled Variety)
Chalcedony (a cryptocrystalline variety of Quartz, SiO2)
Fluorite
Fluorite (Calcium Fluoride, CaF2)
Quartz Vein on Matrix
Silicon Dioxide (SiO2)
Flint
Chert (a form of cryptocrystalline quartz, chemical formula SiO₂)
Snowflake Obsidian
Obsidian (volcanic glass) with Cristobalite inclusions
Quartz (chalcedony variety) or Limestone with Quartz Veins
SiO2 (for Quartz/Chalcedony); CaCO3 (for Limestone)
Banded Iron Formation
Banded Iron Formation (BIF)
Granite
Plutonic felsic igneous rock
Chert (Black Chert/Flint)
Silicon Dioxide (SiO2)
Granite
Granite (Phaneritic Igneous Rock)
Granite Pebble
Igneous Intrusive Rock (Quartz-Feldspar-Mica Phenocrysts)
Olivine in Basalt matrix
Peridotite (Mg, Fe)2SiO4
Druzy Quartz
Quartz (Silicon Dioxide, SiO2)
Quartzite
Quartzite (primarily SiO2)
Lapis Lazuli
A metamorphic rock primarily composed of lazurite (Na,Ca)8[(S,SO4,Cl)2|(Al6Si6O24)], calcite (CaCO3), and pyrite (FeS2).
Granite
Felsic Plutonic Rock (primarily SiO2)
Granite
Phaneritic plutonic rock (Quartz + Feldspar + Mica)
Calcite
Calcite (CaCO3)
Sandstone (Ferruginous)
Arenite (with Iron Oxide)
Granite
Granite (Felsic Plutonic Rock)
Granite
Plutonic felsic igneous rock
Quartz (Yellow/Citrine variety)
Crystalline Silicon Dioxide (SiO2)
Olivine in Basalt
Peridotite / Forsterite ((Mg,Fe)2SiO4)