Industrial Byproduct (Anthropogenic Rock Like Material)

Unakite-like jasper / epidote–feldspar rock

Epidote–feldspar–quartz aggregate; commonly marketed as unakite or brecciated jasper

Red Sandstone

Arenite (primarily Quartz with Hematite cement)

Polymict breccia

Lithic breccia; clast-rich, iron-stained breccia

Granitic Pegmatite

Granite Pegmatite (coarse-grained intrusive igneous rock)

Brachiopod Fossil in Limestone

Phylum Brachiopoda (likely Order Spiriferida), CaCO3 (Calcite)

Bauxite

Bauxite (Mixture of Al(OH)3, AlO(OH), and Fe2O3)

Pegmatite

Intrusive Igneous Rock

Shale

Laminated Mudstone (Shale)

Colorless faceted gemstone, likely quartz

Quartz (SiO₂), probably rock crystal; exact identification is uncertain from the strongly backlit image

Peridotite (Dunite/Peridot Xenolith)

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

Rounded gray-brown pebble

Indeterminate; likely weathered quartz-rich sandstone or fine-grained volcanic rock

Tumbled dark stone, likely basalt or gabbro

Basalt (fine-grained mafic rock), possibly gabbro; mainly plagioclase and pyroxene

Plume Agate or Moss Agate

Agate (SiO2)

Serpentine

Hydrous magnesium iron silicate, (Mg,Fe)3Si2O5(OH)4

Small brown rock fragment; exact identification uncertain

Unidentified fine-grained lithic fragment

Tumbled yellow chalcedony (possibly citrine or pale agate)

Chalcedony, microcrystalline quartz (SiO₂); exact variety cannot be confirmed visually

Epidote-rich rock (likely epidotite or altered basalt)

Epidote, Ca₂(Al,Fe³⁺)₃(SiO₄)₃(OH); possibly epidote-bearing mafic rock

Quartzite

Quartzite (primarily SiO2)

Weathered iron-rich quartz vein in altered host rock

Goethite–hematite limonite with quartz and iron-oxide alteration

Arsenopyrite with Schist Matrix

Arsenopyrite (FeAsS)

Petrified Wood

Fossilized wood / Silicified wood

Quartz crystal with dark inclusions

Quartz (SiO₂), likely tourmaline- or chlorite-included quartz

Diamond (or Simulant)

Carbon (C) or relevant simulant formula (e.g., ZrO2 for Cubic Zirconia)

Vesicular basalt (possibly slag-like volcanic rock)

Basalt, predominantly plagioclase–pyroxene–olivine; exact identification is uncertain from the photograph

Iron-stained quartz or quartzite fragment

Quartz (SiO₂), possibly iron-oxide-stained quartzite

Quartz Pebble

Silicon Dioxide (SiO2)

Silver (Sterling Silver Jewelry)

Argentum (Ag) mixed with Copper (Cu)

Green aventurine (likely)

Quartz, SiO₂, containing fuchsite mica or other green inclusions

Basalt

Basalt (Aphanitic Mafic Volcanic Rock)

Basalt

Basalt (Aphanitic Mafic Igneous Rock)

Quartz Sand Gravel

Silicon Dioxide (SiO2)

Sandstone

Arenite (SiO2 primarily)

Orange glassy slag (industrial by-product)

Iron-rich silicate glass; composition varies, commonly Fe–Ca–Al silicate

Blue-gray stone pebble (possibly slag or a weathered rock)

Unidentified fine-grained rock; composition cannot be determined from the image

Purple glassy pebble, possibly slag glass

Unidentified; likely man-made glass rather than a natural mineral

Polished brecciated jasper

Jasper, an opaque microcrystalline variety of quartz (SiO₂), with iron-oxide coloration and possible breccia fragments

Kimberlite

Kimberlite

Pebble

Lithic fragment / Water-worn rock

Fulonite (Fulgurite-like)

Fulgurite (SiO2 fused silica/lechatelierite)

Sandstone (Quartz-rich)

Arenite (primarily SiO2)

Red Jasper (Quartz)

Silicon Dioxide (SiO2) with Iron impurities

Anthracite Coal

Anthracite (Carbon C)