Industrial Byproduct (Anthropogenic Rock Like Material)

Sandstone

Arenite (SiO2 with various cementing agents)

Clay (as a rock-forming material)

Clay minerals (e.g., Kaolinite group, Smectite group, Illite group, Chlorite group)

Graywacke

Lithic Sandstone (Graywacke)

Quartz

Silicon Dioxide (SiO2)

Quartzite

Quartzite (SiO2)

Sandstone

Arenite

Breciated Jasper

Silicon Dioxide (SiO2) with iron oxide inclusions

Basalt

Basalt (Mafic volcanic rock)

South Korean 100 Won Coin (Cupronickel)

Cupronickel Alloy (75% Cu, 25% Ni)

Chert (Nodule)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Quartz Vein in Siltstone

Silicon Dioxide (SiO2) within Sedimentary/Metamorphic Matrix

Vesicular Basalt

Extrusive Mafic Igneous Rock (Vesicular Basalt)

Milky Quartz

Silicon Dioxide (SiO2)

Fossilized Bone Fragment

Vertebrate Fossil

Limonite (Iron Ore)

Limonite (mixture of hydrated iron(III) oxide-hydroxides)

Quartz and Iron Oxide

Quartz (Silicon Dioxide, SiO2) with possible Limonite/Hematite inclusions

Sandstone

Arenite (typically SiO2 based)

Uncertain polymict breccia or altered volcanic rock

Likely hydrothermally altered volcanic breccia; exact mineral identification requires testing

Rounded river or beach pebble

Likely quartz-rich sandstone or quartzite; exact identification requires a close-grained view and hardness test

Rounded yellow-brown pebble

Likely iron-stained sandstone or quartz-rich river cobble

Yellow Jade (Quartzite Jade)

Quartzite (SiO2)

Man-made Carved Stone (Scream Mask/Skull motif)

Carved Soapstone or Serpentine-rich rock

Granite Gravel (Pebble)

Intrusive Felsic Igneous Rock

Agate

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Amethyst cluster

Quartz, silicon dioxide (SiO₂), purple variety colored mainly by iron impurities and irradiation

Silver (Sterling Silver Jewelry)

Argentum (Ag) mixed with Copper (Cu)

Quartzite Pebble

Quartzite (SiO2 with minor impurities)

Quartz-lined vesicle in basalt (amygdaloidal basalt)

Amygdaloidal basalt with drusy quartz; predominantly plagioclase, pyroxene, and iron oxides

Weathered river pebble, likely quartz-rich sandstone or iron-stained quartzite

Provisional identification: quartz-rich sandstone/quartzite; exact composition cannot be confirmed from the image

Sandstone with Iron Staining

Arenite (SiO2 with FeO(OH) impurities)

Pumice

Pumicite

Sandstone

Arenite (SiO2 with various cementing minerals)

Sandstone (with concrete/human-made layer)

Clastic Sedimentary Rock (primarily Quartz/Feldspar grains)

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Greywacke (Sandstone)

Lithic wacke

Quartz (Druzy on Matrix)

Silicon Dioxide (SiO2)

Chalcedony

Chalcedony (cryptocrystalline Silicon Dioxide, SiO2)

Chert (containing Flint nodules)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Likely iron-rich slag or weathered ironstone

Hematite–goethite-rich material (Fe₂O₃/FeO(OH)); possibly industrial iron slag

Rough amethyst-bearing quartz specimens

Quartz, SiO₂; purple coloration from trace iron and irradiation

Granite-like igneous rock

Likely medium-grained granite or granodiorite; quartz–feldspar–mica aggregate

Pegmatite

Pegmatite (felsic intrusive igneous rock)