Small seashell fossil or shell fragment
Likely calcium-carbonate shell material, chiefly aragonite or calcite; exact species indeterminate
fossil
Category
Industrial By Product
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Chert (and associated Sedimentary rocks)
Microcrystalline Silica (SiO2)
sedimentary
Green Glass Slag
Amorphous Silicon Dioxide (SiO2) with metal oxide impurities
mineraloid (man-made)
Marble
Marble (primarily Calcite, CaCO3 or Dolomite, CaMg(CO3)2)
Metamorphic Rock
Quartzite
Quartzite (SiO2-rich metamorphic rock)
metamorphic
Chert (Flint)
Silicon dioxide (SiO2)
sedimentary
Chert (Flint)
Silicon Dioxide (SiO2)
sedimentary
Pumice
Pumice (Volcanic Rock)
igneous
Marble
Metamorphic rock primarily composed of Calcite (CaCO3)
metamorphic
Pumice
Pumice (Amorphous volcanic glass)
igneous
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Pumice
Vesicular Rhyolite or Andesite (Amorphous volcanic glass)
igneous
Gabbroic or basaltic rock with weathered veins
Likely mafic igneous rock, possibly olivine gabbro or porphyritic basalt; exact identification requires testing
igneous
Iron-rich breccia (hematite–goethite rock)
Hematite (Fe₂O₃) and goethite (FeO(OH)) ironstone, likely ferruginous breccia
sedimentary
Weathered jasper-rich ironstone
Brecciated jasper/chert with iron oxides and hydroxides (SiO₂ with hematite, goethite, and limonite)
sedimentary
Granite
Granite
igneous
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Basalt
Basalt (Mafic volcanic rock)
igneous
Pumice
Pumice (a highly vesicular amorphous volcanic glass)
igneous
Biotite (Black Mica)
K(Mg,Fe)3AlSi3O10(OH,F)2
mineral
Rhodonite
Rhodonite, manganese inosilicate — MnSiO₃; the specimen may include quartz, feldspar, and black manganese-oxide minerals in the matrix
mineral
Graphite-bearing schist (probable)
Graphite–quartz–mica schist; chiefly graphite (C), quartz (SiO₂), and mica
metamorphic
Quartz (Common or Milky)
Silicon Dioxide (SiO2)
mineral
Clay (as a rock-forming material)
Clay minerals (e.g., Kaolinite group, Smectite group, Illite group, Chlorite group)
Mineral
Pearl necklace
Pearl (biogenic calcium carbonate, chiefly aragonite; CaCO₃)
gemstone
Pumice
Pumice (Vesicular Felsic to Intermediate Volcanic Rock)
igneous
Basalt (Vesicular)
Extrusive igneous rock with vesicular texture
igneous
Pumice
Pumice (Highly vesicular volcanic glass)
igneous
Botryoidal Hematite (Iron Ore)
Iron(III) oxide (Fe2O3)
mineral
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Iron-rich quartzite or ferruginous metamorphic rock
Ferruginous quartzite, likely hematite/goethite-bearing quartzite; SiO₂ with Fe₂O₃/FeO(OH)
metamorphic
Pink Granite
Granite (Felsic Plutonic Igneous Rock)
igneous
Pebble (likely Quartzite or Chert)
Clastic Sediment, potentially composed of SiO₂ (Quartz)
Mineral, Sediment
Chert / Flint
Cryptocrystalline quartz (SiO2)
sedimentary
Small marine shell fragment
Calcareous shell, primarily calcium carbonate (aragonite or calcite); exact taxon indeterminate
fossil
Pyrite-bearing quartz vein rock
Pyrite (FeS₂) in quartz, possibly with iron-oxide weathering products
mineral
Chert
Microcrystalline quartz (SiO2)
sedimentary
Bornite (“peacock ore”), likely weathered copper sulfide
Bornite, Cu₅FeS₄; possibly chalcopyrite, CuFeS₂, with iridescent tarnish
mineral
Serpentinite
Serpentinite; chiefly serpentine-group minerals (lizardite, chrysotile, antigorite), with magnetite and relic mafic minerals
metamorphic
Calcite crystal
Calcite (CaCO₃)
mineral
Slag (Industrial Glassy Byproduct)
Anthropogenic silicate byproduct (Slag)
Mineral-like byproduct (often mistaken for igneous rock or meteorite)
Diamond (or Diamond Simulant)
C (Carbon) or synthetic equivalent
gemstone