Industrial Byproduct (Anthropogenic Material)

Polished dendritic jasper or agate slab

Microcrystalline quartz (SiO₂), likely jasper with chalcedony and iron/manganese dendrites

Diamond

Carbon (C)

Limestone

Calcium Carbonate (CaCO3)

Chert (and Jasper/Chalcedony mixture)

Microcrystalline Quartz (SiO2)

Chert (with Manganese Dendrites)

Chert (Cryptocrystalline Quartz, SiO2)

Basalt

Basalt (Mafic volcanic rock)

Basalt

Basalt (Mafic volcanic rock)

Chert (specifically Jasper/Flint)

Microcrystalline Quartz (SiO2)

Rough Diamond

Diamond (pure carbon, C)

Diamond

C

Quartzite

Quartzite (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Diamond (Faceted)

Carbon (C)

Diamond (Faceted)

Carbon (C)

Diamond

Carbon (C)

Banded Calcite (often sold as 'Green Onyx')

Calcite (Calcium Carbonate, CaCO3)

Dalmatian jasper

Orbicular microcrystalline quartz rock, commonly rhyolitic or volcanic-feldspar matrix with black arfvedsonite/alkali-amphibole inclusions

Diamond (Macled/Crystal fragment)

Carbon (C), isometric crystal system

Polished red banded stone, likely rhodonite

Rhodonite — manganese inosilicate, MnSiO₃; possibly rhodochrosite or dyed quartz

Bauxite

Aluminium ore / Hydrated aluminium oxides (AlOx(OH)3-2x)

Chert (Flint/Jasper)

Silicon Dioxide (SiO2)

Diamond (in a jewelry setting)

Cubic Carbon (C)

Polished ocean jasper (orbicular jasper), probable

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

Red Sandstone

Arenite (typically with iron oxide/hematite cement)

Tumbled chalcedony (likely moss or dendritic agate)

Microcrystalline quartz, SiO₂, with iron-oxide inclusions

Bituminous Coal

Bituminous coal (Lithotype: Durain/Clarain)

Iron meteorite fragment (likely weathered meteorite)

Fe–Ni metal, commonly kamacite with taenite; possible stony-iron or iron-oxide fusion crust

Chert (Flint variety)

Microcrystalline Quartz (SiO2)

Diamond (in Ring Setting)

Diamond (Pure Carbon, C)

Sandstone

Arenite (SiO2 principal)

Rainbow aura quartz cluster

Quartz, silicon dioxide (SiO₂), artificially coated with a thin metallic film

Polished tiger’s-eye

Tiger’s-eye, a chatoyant quartz variety; SiO₂ with fibrous pseudomorphic crocidolite/goethite inclusions

Diamond

Carbon (C)

Rounded river or beach pebble

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

Uncertain polymict breccia or altered volcanic rock

Likely hydrothermally altered volcanic breccia; exact mineral identification requires testing

Tumbled amber

Amber (fossilized plant resin), chiefly polymerized diterpenoid resin

Quartz-bearing iron-stained breccia

Brecciated quartz/quartzite with iron oxides, chiefly SiO₂ with hematite/goethite and possible feldspar or host-rock fragments

Unidentified weathered rock, possibly quartz-bearing granite or rhyolite

Indeterminate; likely quartz–feldspar-rich silicate rock

Weathered granite or granitic gneiss pebble

Granite; mainly quartz (SiO₂), feldspar, and mica, with possible gneissic alteration

Likely weathered quartz-bearing rock fragment

Indeterminate; appears to contain quartz (SiO₂) with iron-oxide staining, possibly from quartzite, granite, or pegmatite

Sandstone (Ferruginous)

Arenite with Iron-Oxide Cement

Sandstone (Ferruginous)

Arenite (with Iron Oxide cement)