Industrial Byproduct (Anthropogenic Rock)

Quartzite

Quartzite (primarily SiO2)

Quartzite

Quartzite (SiO2)

Quartzite Pebble

Quartzite (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Large calcite crystal cluster

Calcite (calcium carbonate, CaCO₃)

Chrysocolla-bearing copper ore

Chrysocolla (hydrated copper phyllosilicate), likely with malachite, quartz, and iron oxides

Chrysotile Asbestos

Mg3Si2O5(OH)4

River Cobble (Basalt or Greywacke)

Extrusive Mafic Igneous Rock (likely Basalt)

River/Stream Pebble

Clast / Detrital Grain / Rounded Sedimentary Particle (Compositionally variable, commonly Quartz, Feldspar, Chert, or other resistant rock fragments)

Quartzite (specifically an iron-stained or Carnelian-colored variety)

Silicon Dioxide (SiO2) with iron oxide inclusions

Porphyritic Andesite (often called Chinese Writing Stone)

Porphyritic Basaltic Andesite with Feldspar Phenocrysts

Dark river pebble, likely basalt or fine-grained volcanic rock

Basalt (probable); mostly plagioclase and pyroxene, with possible magnetite

Diamond (or Cubic Zirconia simulant)

Carbon (C) - Diamond / Zirconium dioxide (ZrO2) - CZ

Tumbled quartz-rich rock, likely quartzite or milky quartz with iron-oxide staining

Quartzite (primarily SiO₂), possibly with hematite/goethite staining and minor feldspar or mica

Desert Rose

Selenite Rose (Gypsum: CaSO4·2H2O)

Quartzite

Quartzite (SiO2)

Diamond (or diamond simulant)

C

One Pound Coin (UK)

Nickel-Brass Alloy (Cu-Zn-Ni)

Unakite-like jasper / epidote–feldspar rock

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

Weathered quartz-rich stone, possibly fossiliferous limestone

Indeterminate; likely calcite-rich limestone (CaCO₃) or weathered quartz-bearing rock

Quartzite

Metamorphosed Quartz Sandstone (SiO2)

Clear quartz sphere or polished quartz cabochon (tentative)

Quartz, silicon dioxide (SiO₂); appearance may also be consistent with ordinary glass, which cannot be ruled out from the image alone

Rough Dark Green Sapphire

Corundum (Al2O3)

Brecciated jasper, possibly rainforest jasper or brecciated rhyolite

Brecciated microcrystalline quartz (SiO₂), commonly called jasper; the green portions may contain epidote, chlorite, or iron-bearing silicates, while red-brown areas are typically hematite or other iron oxides

Druzy Quartz (on Geode Fragment)

Silicon Dioxide (SiO2)

Greenschist (Chlorite Schist)

Greenschist (Metamorphic rock dominated by chlorite, actinolite, and epidote)

Green Glass Cullet / Recycled Glass

Amorphous Silicon Dioxide (SiO2) with various metal oxides

Not a rock

Not a rock

Granitic Pegmatite with Schorl

Granitic Pegmatite (NaAlSi3O8, KAlSi3O8, SiO2) with Schorl (NaFe3Al6(BO3)3Si6O18(OH)4)

Red Garnet

Garnet Group (e.g., Pyrope, Almandine, Spessartine, Grossular, Andradite, Uvarovite)

Diamond

C (Carbon)

Diamond (or Simulant)

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

Banded Iron Formation (BIF)

Banded Iron Formation

Fluorite (likely Green Fluorite variant)

Calcium Fluoride (CaF2)

Opalite

Synthetic Opalized Glass / Man-made Glass

Rough Garnet in Matrix

Almandine Garnet (Fe3Al2Si3O12)

Banded Iron Formation (BIF) with Quartz

Banded Iron Formation, often composed of alternating layers of hematite (Fe2O3) or magnetite (Fe3O4) and chert (microcrystalline quartz, SiO2)

Agate Slices and Clear Quartz Points

Agate (SiO2 Chalcedony) and Clear Quartz (SiO2 Crystalline)

Dark volcanic pebble, likely basalt

Basalt; fine-grained mafic rock composed mainly of plagioclase, pyroxene, and commonly olivine or magnetite

Sea Glass (specifically Frosted White)

Amorphous Silica (substance: Sodium-calcium silicate glass)

Anthracite Coal

Anthracite (Carbon-based sedimentary-derived metamorphic rock)

Silicon

Element Si