Man Made Material (Anthropogenic 'Mineraloid')

Nickel coin (U.S. currency)

Cupronickel (75% Copper, 25% Nickel alloy)

Chert (Black Chert or Flint)

Silicon Dioxide (SiO2)

Chert (Flint / Jasper variant)

Microcrystalline Quartz (SiO2)

Greenstone

Metamorphic mafic rock (chlorite-actinolite-epidote schist)

Flint / Chert

Microcrystalline quartz (SiO2)

Tektite (Indochinite)

Tektite (Amorphous Silica Glass)

Likely clear quartz crystal (possibly cut/polished quartz or glass imitation)

Quartz, silicon dioxide (SiO₂)

Carnelian cabochon

Orange-red variety of chalcedony (microcrystalline quartz), SiO₂

Coquina

Biogenic Limestone (mostly Calcium Carbonate, CaCO3)

Chert (Black Flint)

Silicon Dioxide (SiO2)

Red Sandstone

Arenite (Iron-rich)

Nephrite Jade

Ca2(Mg,Fe)5Si8O22(OH)2

Mother of Pearl (Nacre) / Shell Fragment

Biogenic Calcium Carbonate (Aragonite and Conchiolin)

Chert (Yellow Jasper/Flint)

Microcrystalline Quartz (SiO2)

Chert (and/or Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (variations include Flint/Jasper)

Cryptocrystalline Quartz (SiO2)

Chert / Jasper

Silicon Dioxide (SiO₂)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Fossilized coral with attached shell

Likely fossil coral (Scleractinia or Tabulata), with a bivalve or gastropod shell; exact identification requires microscopy

Chert (Flint)

SiO2 (Microcrystalline Quartz)

Fossil or modern bivalve shell

Calcium carbonate shell, likely aragonite (CaCO₃); exact species cannot be determined from the image

Beaded gemstone bracelet

Indeterminate; likely small polished mineral beads, possibly turquoise or dyed stone, with metal and glass components

Likely smoky quartz pendant

Smoky quartz, silicon dioxide (SiO₂), quartz variety colored by irradiation-related defects

Polished amber inclusion specimen

Amber (fossilized plant resin), commonly succinite; organic mineraloid

Botryoidal chalcedony with iron-oxide staining

Microcrystalline quartz (SiO₂), likely iron-oxide-bearing chalcedony

Diamond

Carbon (C)

Green Slag Glass

Amorphous Silicon Dioxide (with metallic impurities)

White pebbles (rock material not identifiable from the image)

Undetermined; the smooth, pale pieces could be quartz, quartzite, or another light-colored rock

Chert (often called Flint)

Chert (Cryptocrystalline Quartz, SiO2)

Fossilized gastropod (likely nerite or related sea snail)

Gastropoda; shell composed originally of aragonite/calcite, commonly replaced or infilled by calcite

Limonite (Iron Ore)

Limonite (an FeO(OH)·nH2O mineraloid, not a true mineral due to variable composition)

Orange glassy slag (industrial by-product)

Iron-rich silicate glass; composition varies, commonly Fe–Ca–Al silicate

Black-and-white agate geode pendant

Agate (microcrystalline quartz, SiO₂), likely a hollow geode slice with chalcedony and drusy quartz

Amber (polished piece)

Fossilized tree resin; amber is an organic mineraloid, not a true mineral

Amethyst gemstone ring

Quartz, purple variety — SiO₂

Likely flint (dark chert)

Microcrystalline quartz (SiO₂), commonly called chert or flint

Flint (chert) nodule

Microcrystalline quartz (SiO₂), occurring as a flint/chert nodule in limestone

Granite / Diorite (Granodiorite)

Granodiorite / Quartz Diorite

Green glassy slag (often sold as “sea glass” or “green obsidian”)

Industrial vitreous slag; primarily amorphous silicate glass, composition variable

Quartzite

Metamorphic Quartzite (SiO2)

Flint (chert), likely a worked stone flake

Microcrystalline quartz (SiO₂); cryptocrystalline variety of quartz

Polished orbicular granite heart

Granite, commonly quartz–alkali feldspar–plagioclase–biotite granite; exact locality-dependent