Not A Natural Rock

Pink Granite

Phaneritic Felsic Igneous Rock

Ironstone Concretion / Goethite Nodules

Ironstone (composed primarily of Goethite FeO(OH) and Limonite)

Blue Chalcedony (Tumbled)

Silicon Dioxide (SiO2)

Pink Granite

Phaneritic Felsic Igneous Rock (Granite)

Dyed Agate Slice

Silicon Dioxide (SiO2) with artificial colorants

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Rounded gray stone, likely slate or fine-grained sandstone

Probable slate (low-grade metamorphosed shale) or lithic sandstone; exact identification requires testing

Pink Granite

Phaneritic Felsic Igneous Rock (high K-feldspar)

Slate

Metamorphosed Shale (Fine-grained Foliated Metamorphic Rock)

Shale (with minor calcite veining)

Clastic sedimentary rock (primarily clay minerals and quartz)

Peridotite (Dunite/Peridot Xenolith)

Peridotite (predominantly Olivine (Mg, Fe)2SiO4)

Pumice

Pumice (Amorphous volcanic glass)

Tumbled blue stone with a drilled hole

Likely dyed or naturally blue chalcedony/agate; identity cannot be confirmed from the photo

Smoky Quartz with Hematite Inclusions

Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3) inclusions

Blue Dyed Agate

Cryptocrystalline Quartz (SiO2)

Chakra Stone (Composite / Man-made Bonded Gemstones)

Composite of Quartz, Lapis Lazuli, Aventurine, Tiger's Eye, and Jasper (SiO2, (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2, etc.)

Shungite (Noble/Type II)

Non-crystalline carbon (Fullerene-bearing carbonaceous rock)

Granite

Phaneritic Igneous Rock (primarily Quartz, Feldspar, and Mica)

Metal Chain (Likely Steel or a Steel Alloy)

Steel (primarily iron and carbon); specific alloy unknown

Granite

Granite (compositional mixture of Quartz, Feldspar, and Mica)

Pink Granite

Phaneritic Felsic Igneous Rock (Granite)

Polished ocean jasper / orbicular jasper

Microcrystalline quartz (chalcedony), SiO₂, with iron-oxide and other mineral inclusions

Smoky Quartz

Silicon Dioxide (SiO2)

Natural Pearl (appearing in a jewelry setting)

Calcium Carbonate (mostly Aragonite), CaCO3 with Conchiolin

Small polished brown stone

Indeterminate; possibly tumbled jasper, brown agate, or another iron-stained silicate

Amethyst

Quartz (Silicon Dioxide with Iron impurities), SiO2

Jasper and Yellow Chert (Tumbled)

Microcrystalline Quartz (SiO2)

Iron-rich sandstone or lateritic rock

Ferruginous sandstone; predominantly quartz (SiO₂) cemented or stained by iron oxides/hydroxides

Granite

Phaneritic plutonic igneous rock (SiO2-rich)

Sandstone (Weathered Coastal Boulder)

Arenite (composed primarily of SiO2)

Brick fragment (Man-made material)

N/A (Fired clay)

Fossilized tooth, likely mammalian molar

Indeterminate Mammalia; mineralized dentine and enamel

Milky and Citrine-type Quartz

Silicon Dioxide (SiO2)

Crushed Limestone

Calcium Carbonate (CaCO3)

Bull Quartz with Mica and Host Rock

Massive Quartz (SiO2) with Muscovite/Chlorite inclusions

Sandstone (Ferruginous)

Arenite (SiO2 with Fe2O3 cement)

Gneiss (Metamorphosed Granitic Rock)

Gneiss (composed mainly of quartz, feldspar, biotite, and/or hornblende)

Weathered iron-rich rock, possibly laterite or limonite-bearing stone

Hydrated iron oxides/hydroxides, chiefly limonite-goethite mixture; exact identification requires testing

Concrete

Anthropogenic Sedimentary Rock (Hydrated Calcium Silicate)

Obsidian

Volcanic Glass (Amorphous Silicon Dioxide)

Pink Granite

Granite (Phaneritic Felsic Igneous Rock)

Granite

Phaneritic plutonic felsic igneous rock