Mother of Pearl (Nacre) / Shell Fragment
Biogenic Calcium Carbonate (Aragonite and Conchiolin)
fossil
Category
Man Made Material
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Chert (Yellow Jasper/Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (and/or Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Chert (variations include Flint/Jasper)
Cryptocrystalline Quartz (SiO2)
sedimentary
Chert / Jasper
Silicon Dioxide (SiO₂)
sedimentary
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Carnelian cabochon
Orange-red variety of chalcedony (microcrystalline quartz), SiO₂
gemstone
Fossilized coral with attached shell
Likely fossil coral (Scleractinia or Tabulata), with a bivalve or gastropod shell; exact identification requires microscopy
fossil
Chert (Flint)
SiO2 (Microcrystalline Quartz)
sedimentary
Coquina
Biogenic Limestone (mostly Calcium Carbonate, CaCO3)
sedimentary
Fossil or modern bivalve shell
Calcium carbonate shell, likely aragonite (CaCO₃); exact species cannot be determined from the image
fossil
Beaded gemstone bracelet
Indeterminate; likely small polished mineral beads, possibly turquoise or dyed stone, with metal and glass components
gemstone
Likely smoky quartz pendant
Smoky quartz, silicon dioxide (SiO₂), quartz variety colored by irradiation-related defects
gemstone
Botryoidal chalcedony with iron-oxide staining
Microcrystalline quartz (SiO₂), likely iron-oxide-bearing chalcedony
mineral
Diamond
Carbon (C)
mineral
Chert (often called Flint)
Chert (Cryptocrystalline Quartz, SiO2)
sedimentary
White pebbles (rock material not identifiable from the image)
Undetermined; the smooth, pale pieces could be quartz, quartzite, or another light-colored rock
sedimentary
Fossilized gastropod (likely nerite or related sea snail)
Gastropoda; shell composed originally of aragonite/calcite, commonly replaced or infilled by calcite
fossil
Orange glassy slag (industrial by-product)
Iron-rich silicate glass; composition varies, commonly Fe–Ca–Al silicate
mineral
Black-and-white agate geode pendant
Agate (microcrystalline quartz, SiO₂), likely a hollow geode slice with chalcedony and drusy quartz
mineral
Amethyst gemstone ring
Quartz, purple variety — SiO₂
gemstone
Granite / Diorite (Granodiorite)
Granodiorite / Quartz Diorite
igneous
Green glassy slag (often sold as “sea glass” or “green obsidian”)
Industrial vitreous slag; primarily amorphous silicate glass, composition variable
mineral
Quartzite
Metamorphic Quartzite (SiO2)
metamorphic
Polished orbicular granite heart
Granite, commonly quartz–alkali feldspar–plagioclase–biotite granite; exact locality-dependent
igneous
Chert (Flint/Chalcedony)
Silicon Dioxide (SiO2)
sedimentary
Chert Arrowhead
Chert (Cryptocrystalline variety of Quartz, SiO2)
sedimentary
Raw Diamond
Carbon (C)
gemstone
Chert (Common Opal/Jasper variety)
Cryptocrystalline Quartz (SiO2)
sedimentary
Chert (and/or Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Diamond (in jewelry setting)
Carbon (C)
mineral
Tumbled chalcedony or quartz pebble
Microcrystalline quartz, SiO₂ (likely chalcedony); exact identification is uncertain from the image
mineral
Chert (Flint)
Silicon Dioxide (SiO2)
sedimentary
Chert (Flint)
Chert (SiO2)
sedimentary
Chert (Green Chert or Jasper)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Flint)
Silicon Dioxide (SiO2)
sedimentary
Chert (Flint)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Chert (varietal Chalcedony or Flint)
Silicon dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Polished brecciated jasper pendant
Jasper, an opaque microcrystalline variety of chalcedony (mostly SiO₂), with iron-oxide staining and likely brecciation
mineral
Chert (Flint)
Silicon Dioxide (SiO2)
sedimentary
Red Sandstone
Arenite (Fe2O3 enriched)
sedimentary