Bivalve Fossil (Clam)
Class Bivalvia (e.g., Mercenaria or similar genus), composed of CaCO3 (Aragonite/Calcite)
fossil
Category
Mineral Precipitate (Anthropogenic Context)
Browse mineral precipitate (anthropogenic context) specimens identified by the Rock Identifier community.
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Likely tumbled quartz-bearing rock or glittery quartz specimen
Quartz, silicon dioxide (SiO₂), possibly included quartz or quartzite
mineral
Chert (Arrowhead Shard)
Microcrystalline silica (SiO2)
sedimentary
Fossiliferous Limestone with Crinoid Stem fragment
Calcite (CaCO3) containing Crinoidea fossils
sedimentary
Quartz with Chlorite inclusions
SiO2 with (Mg,Fe)3(Si,Al)4O10(OH)2⋅(Mg,Fe)3(OH)6
mineral
Iron-stained quartz vein rock
Quartz-rich vein material with iron oxides/hydroxides (quartz, SiO₂, stained by hematite/goethite); likely hosted in a metamorphic rock
metamorphic
Exposed aggregate concrete (stone-chip surface)
Portland-cement concrete containing natural aggregate; not a natural rock
sedimentary
Greenstone (Celadonite-bearing Volcanic)
Hydrothermally altered basalt or andesite with Celadonite (K(Mg,Fe2+)(Fe3+,Al)Si4O10(OH)2)
metamorphic
Chert (Yellow Jasper)
Cryptocrystalline Quartz (SiO2)
sedimentary
Basalt Metate
Vesicular Basalt
igneous
Chert (Arrowheads)
Microcrystalline Quartz (SiO2)
sedimentary
Concrete / Conglomerate (Man-made)
Artificial Conglomerate (Cementitious Composite)
sedimentary
Fossilized bone fragment, possibly mammalian long bone
Mineralized bone (commonly apatite, Ca₅(PO₄)₃(OH,F,Cl), replacing original bone)
fossil
Amethyst (Tumbled/Weathered Quartz)
Amethyst (SiO2 with iron impurities)
mineral
Black Onyx
Black Chalcedony (SiO2)
mineral
Ferruginous Quartzite (also known as Ironstone or Gossan)
Ferruginous Quartzite with Goethite/Hematite staining
metamorphic
Mixed gravelly conglomeratic road aggregate
Polymictic clast-supported conglomerate or fill; composition varies, commonly quartz, feldspar, basalt, and weathered rock fragments
sedimentary
Red Sandstone
Clastic Terrigenous Sedimentary Rock (primarily SiO2 with Fe2O3 coating)
sedimentary
Fluorite
Fluorite (Calcium Fluoride, CaF2)
mineral
Olivine Diabase Porphyry
Porphyritic Olivine-Bearing Diabase (Micro-Gabbro)
igneous
Chert Arrowhead
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Septarian or Nodular variety)
Microcrystalline Quartz (SiO2)
sedimentary
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Schist (Biotite/Mica Schist)
Medium-grade regional metamorphic rock (rich in Phyllosilicates)
metamorphic
Sandstone Concretion
Ferruginous Sandstone Concretion (Primarily SiO2 with Iron Oxide cement)
sedimentary
Sea Shell (Fighting Conch Fragment)
Calcium Carbonate (CaCO3) - Strombus alatus fragment
sedimentary (biogenic)
Pink feldspar-bearing pegmatite
Orthoclase–microcline feldspar, chiefly KAlSi₃O₈, in a granitic pegmatite matrix
igneous
Chert (Arrowhead Fragment)
Silicon Dioxide (SiO2)
sedimentary
Sea Glass
Man-made silicate glass
sedimentary
Conglomeratic gravel / polymictic breccia
Polymictic rudite, likely anthropogenic or beach/stream gravel; composition varies
sedimentary
Quartz-veined Limestone
Sedimentary limestone with quartz/calcite veinlets
sedimentary
Quartz Geode
Silicon Dioxide (SiO2)
sedimentary
Basalt (with Brass Inlay)
Basalt (Mafic volcanic rock)
igneous
Green Sea Glass
Man-made vitreous material (silica glass)
gemstone
Chert (Arrowhead)
Microcrystalline Quartz (SiO2)
sedimentary
Chert Arrowhead (Lithic Artifact)
Microcrystalline Quartz (SiO2)
sedimentary
Chert Arrowhead (Projectile Point)
Microcrystalline Quartz (SiO2)
sedimentary
Chert Arrowhead
Microcrystalline Quartz (SiO2)
sedimentary
Unidentified Rock Fragment
Unknown
Rock
Green sea glass (likely)
Anthropogenic glass, not a mineral; composition commonly soda–lime silicate glass
mineral
Chert (Nodule)
Silicon Dioxide (SiO2)
sedimentary
Yellow Jasper
Silicon Dioxide (SiO2)
sedimentary