Chert (specifically Jasper/Carnelian variety)
Microcrystalline quartz (SiO2)
sedimentary
Category
Mineralogical Specimen
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Mica (Biotite and Muscovite) in Matrix
Potassium aluminum silicate with iron/magnesium (KAl2(AlSi3O10)(F,OH)2 / K(Mg,Fe)3AlSi3O10(F,OH)2)
igneous
Pink tourmaline crystal (likely polished or rough-cut)
Elbaite, Na(Li₁.₅Al₁.₅)Al₆(Si₆O₁₈)(BO₃)₃(OH)₃
gemstone
Banded Calcite (Honey Calcite)
Calcium Carbonate (CaCO3)
mineral
Iron-stained Quartz
Silicon Dioxide with Limonite (SiO2 + FeO(OH)·nH2O)
mineral
Portable Ceramic Space Heater
Polished Acrylonitrile Butadiene Styrene (ABS) Plastic with Ceramic Heating Elements
not a rock (synthetic/industrial object)
Gneiss
Foliated quartz–feldspar gneiss, likely biotite-bearing
metamorphic
Quartz-veined dark metamorphic rock, likely marble or serpentinite
Calcite- or magnesite-veined serpentinite/marble; exact identification requires testing
metamorphic
Fossilized marine shell fragment
Likely a bivalve or gastropod shell preserved as calcite (CaCO₃)
fossil
Chalcedony (Jasper/Agate mix)
Quartz (microcrystalline SiO2)
sedimentary
Chert Nodule (Flint)
Silicon Dioxide (SiO2)
sedimentary
Green Chert (Jasper)
Silicon Dioxide (SiO2)
sedimentary
Coarse-grained granite or granitic gneiss
Granite; primarily quartz (SiO₂), feldspar, and mica, possibly metamorphosed to gneiss
igneous
Small yellow-brown stone, possibly iron-stained quartz or chert
Undetermined; visual evidence is insufficient for a confident identification
mineral
Vein Quartz in Basalt or Mafic Rock
Silicon Dioxide (Quartz veins in volcanic host rock)
igneous
Agate
Silicon Dioxide (Chalcedony), SiO2
gemstone
Chalcopyrite
Copper Iron Sulfide (CuFeS2)
mineral
Iron-Stained Quartz
Silicon Dioxide with Iron Oxide (SiO2 with Fe2O3)
mineral
Jasper
Microcrystalline Quartz (SiO2)
sedimentary
Carnelian
SiO2 (Silicon dioxide)
mineral
Brachiopod Fossil in Sedimentary Rock
Phylum Brachiopoda fossil imprint in sedimentary matrix
fossil
Sandstone Concretion
Sedimentary Concretion (Quartz sand bound by mineral cement)
sedimentary
Quartz in Greenstone
Metamorphic rock with quartz vein (SiO2 / mixed silicates)
metamorphic
Chalcopyrite
Copper Iron Sulfide (CuFeS2)
mineral
Generic Rock Fragment
Rock Fragment
sedimentary
Jasper
Microcrystalline Quartz (SiO2)
mineral
Quartz-veined Basalt or Limestone Pebble
Quartz vein in host rock (Silicate mineral in carbonate or volcanic matrix)
sedimentary
River Cobble (Basaltic/Andesitic)
Mafic to Intermediate Volcanic Rock
igneous
Moss Agate
Silicon dioxide (SiO2) with inclusions
Mineral
Obsidian
Volcanic Glass (Amorphous Silicon Dioxide)
igneous
Vesicular Basalt (Iron Scoria)
Aphanitic Mafic Igneous Rock with Vesicular Texture
igneous
Quartzite Beach Pebble (with Quartz Vein)
SiO2 (Quartzite)
metamorphic
Quartz (Iron-stained)
Silicon Dioxide (SiO2)
mineral
Chert (Common Opal/Chalcedony)
Microcrystalline Quartz (SiO2)
sedimentary
Smoky Quartz (with Druzy/Polished Edge)
Smoky Quartz (Silicon Dioxide, SiO2)
mineral
Cubic Zirconia
Cubic Zirconium Dioxide (ZrO2)
gemstone
Dyed Agate
SiO2
Mineral
White marble tile
Calcite-rich marble (CaCO₃)
metamorphic
Weathered iron-rich mineral concretion
Likely limonite/goethite concretion (hydrated iron oxides), possibly a weathered ironstone fragment
mineral
Chert (Iron-stained)
Microcrystalline Quartz (SiO2)
sedimentary
Quartz Pebble
Quartz (Silicon Dioxide, SiO2)
mineral
Granite Cobble
Granite (Phaneritic Quartz-Feldspar specimen)
igneous