Anthracite Coal
Anthracite (Carbon-based metamorphic rock, 86-97% C)
metamorphic
Category
Industrial Byproduct (Anthropogenic Rock Like Material)
Browse industrial byproduct (anthropogenic rock like material) specimens identified by the Rock Identifier community.
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Schist with Schorl (Black Tourmaline)
NaFe3Al6(BO3)3Si6O18(OH)4 (Schorl)
metamorphic
Red Sandstone
Arenite (primarily SiO2 with Fe2O3)
sedimentary
Pumice (Vesicular Lava)
Pumice
igneous
Schist (Greenschist / Mica Schist)
Foliated Metamorphic Rock (rich in chlorite, muscovite, and quartz)
metamorphic
Chert (variously identified as Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Mica Schist
Schist (Mica-rich Metamorphic Rock)
metamorphic
Milky Quartz
Quartz (SiO2) with iron staining
mineral
Chalcedony (Agate/Chert)
Microcrystalline Quartz (SiO2)
sedimentary
Feldspathic Gneiss
High-grade Metamorphic Rock (Gneiss)
metamorphic
Fossilized Brachiopod
Phylum Brachiopoda (likely Order Spiriferida or Orthida)
fossil
Dendritic Agate (or Dendritic Opal)
SiO2 (for Agate), SiO2·nH2O (for Opal)
Mineral
Clear Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
mineral
Laterite
Laterite (primarily composed of hydrated oxides of iron and aluminum)
Sedimentary Rock (as a residual soil/rock, it's often considered a type of sedimentary rock due to its formation from weathering, though it can cross into soil science)
Milky Quartz (Water-worn Pebble)
Silicon Dioxide (SiO2)
mineral
Limestone (Weathered Pebble)
Calcium Carbonate (CaCO3) / Limestone
sedimentary
Petrified Wood
Silicified Wood (SiO2)
fossil
Likely anthracite coal
Anthracite; predominantly carbon (C), with minor mineral impurities
sedimentary
Polished blue stone, likely sodalite or dyed agate
Sodalite: Na₈(Al₆Si₆O₂₄)Cl₂; exact identification requires testing
mineral
Tumbled rose quartz
Quartz (SiO₂), pink variety
mineral
Rough Sapphire (Corundum)
Corundum (Al2O3)
mineral
Peridot (Olivine)
Magnesium Iron Silicate (Mg, Fe)2SiO4
mineral
Quartzite with Sandstone/Iron staining
Metamorphic Quartzite (SiO2)
metamorphic
Clear quartz sphere or polished quartz cabochon (tentative)
Quartz, silicon dioxide (SiO₂); appearance may also be consistent with ordinary glass, which cannot be ruled out from the image alone
gemstone
Diamond
Diamond (pure Carbon, C)
mineral
Diamond (in Jewelry)
Carbon (C)
mineral
Chert (White Chert / Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Quartzite
Quartzite (primarily SiO2)
metamorphic
Granodiorite
Granodiorite (Na,Ca)(Si,Al)4O8
igneous
Mica Schist
Schist (Muscovite-Biotite Schist)
metamorphic
Exposed Aggregate Concrete (Pea Gravel)
Concrete with Siliceous Alluvial Gravels
sedimentary (man-made conglomerate)
Quartzite
Silica (SiO2)
metamorphic
Diamond
Carbon (C)
Mineral
Chert / Jasper
Silicon Dioxide (SiO2)
sedimentary
Honey Calcite
Calcite (Calcium Carbonate - CaCO3)
mineral
Basalt
Aphanitic Mafic Igneous Rock
igneous
Tufa
Calcareous Tufa (CaCO3)
sedimentary
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Yellow Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Quartz (specifically Milky or Clear Chunk)
Silicon Dioxide (SiO2)
mineral
Sandstone
Sandstone (clastic sedimentary rock, composed predominantly of sand-sized minerals or rock fragments)
Sedimentary Rock
Mica Schist
Mica Schist (predominantly composed of Muscovite or Biotite silicates)
metamorphic