Industrial Byproduct (Anthropogenic Rock Like Material)

Pumice

Pumice (a highly vesicular, silicic volcanic rock)

Sandstone

Arenite (composed primarily of SiO2)

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Likely rough metallic meteorite fragment

Unclassified iron or stony-iron meteorite; identification is uncertain from the image alone

Rough amethyst-bearing quartz specimens

Quartz, SiO₂; purple coloration from trace iron and irradiation

Sandstone with Iron Staining

Arenite (SiO2 with FeO(OH) impurities)

Red Sandstone

Arenite (Iron-rich)

Rounded quartz-rich pebble

Lithic pebble; likely quartz/quartzite with iron-oxide staining

Likely vesicular basalt (scoriaceous basalt)

Basalt, chiefly plagioclase feldspar, pyroxene, and commonly olivine; approximate composition 45–52% SiO₂

Peridot (Olivine)

Olivine, (Mg, Fe)2SiO4

Rounded brown river pebble

Indeterminate lithic fragment; likely weathered sandstone, mudstone, or fine-grained volcanic rock

Weathered quartz-bearing rock fragments

Likely quartz (SiO₂) in a weathered iron-stained host rock; exact identification is uncertain from the image

Corundum (Sapphire variant)

Aluminum Oxide (Al2O3)

Milky Quartz

Silicon Dioxide (SiO2)

Tumbled brown chalcedony (likely chert or agate)

Microcrystalline quartz, SiO₂ (chalcedony); exact variety is uncertain from the image

Sandstone

Sedimentary Clastic Rock

Banded Gneiss

Gneiss (Metamorphic high-grade rock)

Rhodonite-bearing metamorphic rock

Rhodonite (MnSiO₃) with quartz and dark manganese oxides, likely a manganiferous schist or breccia

Unknown brown-and-gold rock fragment

Undetermined; possibly iron-stained quartz, mica schist, or sulfide-bearing ore

Granodiorite

Granodiorite

Shale (or Mudstone)

Laminose Mudrock (composition: clay minerals, quartz, and mica flakes)

Native Copper in Matrix

Native Copper (Cu)

Vesicular basalt pebble

Basalt, a mafic volcanic rock composed mainly of plagioclase feldspar and pyroxene, commonly with olivine

Unidentified rough mineral fragments

Likely quartz- or feldspar-bearing rock; exact identification requires testing

Sandstone

Arenite

Tumbled chalcedony (likely moss or plume agate)

Microcrystalline quartz, SiO₂; chalcedony with possible iron/manganese inclusions

Fossil Snail

Gastropoda (fossilized)

Banded agate tower (likely onyx/chalcedony)

Microcrystalline quartz, SiO₂; commonly called banded agate or black-and-white onyx

Geode with Quartz Crystal Cavity

Silicon Dioxide (SiO2) in Calcareous/Siliceous Matrix

Schist

Mica Schist

Sapphire

Corundum (Al2O3)

Granodiorite

Granodiorite (Intermediate intrusive igneous rock)

Quartz-rich geode or drusy quartz specimen

Quartz, silicon dioxide (SiO₂), likely coating a carbonate or volcanic-rock cavity

Granite-like rock

Felsic intrusive igneous rock, probably granitic or granodioritic

Quartzite Pebble

Quartzite (SiO2 with minor impurities)

Sapphire

Corundum (Al2O3)

Mica Schist

Muscovite/Biotite Schist

Pumice

Pumice (a highly vesicular volcanic glass)

Garnet

Almandine/Pyrope Garnet (Silicate Mineral Group)

Pumice

Pumice (Amorphous volcanic glass)

Pumice or Scoria

Vesicular volcanic rock

Ferruginous Sandstone (Gerrit)

Arenite with Iron Oxide cementation