Not A Rock (Man Made Origin)

Polished jasper pebble

Jasper, an opaque microcrystalline variety of quartz (SiO₂), with possible iron-oxide and other mineral inclusions

Quartz vein in host rock

Milky quartz (SiO₂) with likely metamorphic country rock, possibly gneiss or schist

Likely quartz-rich pebbles

Quartz (SiO₂), possibly milky quartz or quartzite; identification is uncertain from the blurry image

Possible vesicular volcanic rock (scoria)

Scoria; likely basaltic or andesitic, composition unconfirmed from the photo

Iron Slag

Anthropogenic Vitreous Silicate (Byproduct of Smelting)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Tumbled moldavite specimens

Moldavite (natural tektite; silica-rich impact glass), approximately SiO₂ 75–80%

Pink Granite

Phaneritic Felsic Igneous Rock (Granite)

Black Obsidian

Obsidian (Volcanic Glass, SiO2 + impurities)

Chert (likely chalcedony-rich flint)

Microcrystalline quartz, SiO₂ (quartz/chalcedony)

Dark polished stone, possibly black tourmaline or dark quartzite

Uncertain from the image; possible schorl (NaFe₃Al₆(BO₃)₃Si₆O₁₈(OH)₄) or quartz-rich rock

Granite (likely weathered, coarse-grained granite)

Granite; chiefly quartz, feldspar, and dark mica or amphibole

Quartz-rich rock fragment, possibly granite or quartzite

Primarily quartz (SiO₂), with possible feldspar and iron-oxide staining

Quartz-rich rock, possibly milky quartz or quartzite

Quartz (SiO₂), likely with minor iron-oxide or feldspar inclusions

Granite

Plutonic Igneous Rock (composed typically of SiO2, Al2O3, K2O, Na2O, CaO)

Rounded pink granite cobble

Granite, chiefly quartz–alkali feldspar–plagioclase–biotite

Quartz (Tumbled/Water-worn)

Silicon Dioxide (SiO2)

Pink Granite

Phaneritic intrusive igneous rock (Feldspar-Quartz-Mica)

Rough Sapphire (Corundum)

Corundum (Al2O3)

Granite

Granite (Felsic Plutonic Rock)

Granite / Diorite (Granodiorite)

Granodiorite / Quartz Diorite

Note on Image Identification: Textile

N/A (Anthropogenic material)

Red-and-green jasper

Jasper, microcrystalline quartz (SiO₂), colored mainly by iron oxides and possibly chlorite/epidote

Lapis Lazuli (Low Grade)

Lazurite-rich metamorphic rock ((Na,Ca)8(AlSiO4)6(SO4,S,Cl,OH)2)

Breccia

Lithic breccia (angular rock fragments cemented in a finer matrix)

Likely garnet-bearing rock (possibly garnet in dark matrix)

Unconfirmed; potentially almandine garnet (Fe₃Al₂(SiO₄)₃) in a metamorphic host

Emerald in Host Rock

Beryl (Be3Al2Si6O18) containing Chromium and/or Vanadium

Sandstone

Arenite (with iron oxide cement)

Chert (Chert Nodule with Chalky Cortex)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Speckled feldspar-rich pebble

Likely leucocratic granite or granitic pegmatite, chiefly potassium feldspar with dark biotite or amphibole

Granodiorite

Intrusive Igneous Rock

Fossilized bivalve shell

Recrystallized calcium-carbonate shell, commonly fossil oyster or clam (Bivalvia)

Bauxite

Bauxite (Mixture of Hydrous Aluminum Oxides)

Desert Varnish (on Sandstone)

Rock Varnish (composed of Manganese oxides, Iron oxides, and Clay minerals)

Omarolluk (Omar)

Siliceous greywacke concretion

Weathered quartz-rich river cobble

Likely granitic or quartzitic rock; exact identification is uncertain from the photograph

Ferruginous Sandstone (Gozzan/Ironstone)

Arenite with Limonite/Goethite cement (FeO(OH)·nH2O)

Vesicular Basalt (Aqueous Tumbled)

Scoriaceous Basalt

Coal (Bituminous Coal)

Caustobiolith / Sedimentary Rock

Clear quartz (rock crystal)

Quartz, silicon dioxide (SiO₂)

Weathered concrete or cementitious slab (not natural rock)

Artificial calcium-silicate cement composite; likely Portland cement concrete

Blue Sapphire

Corundum (Al2O3 with iron and titanium trace elements)