Anthropogenic (Man Made Material Processed By Nature)

Vesicular basalt (possibly amygdaloidal basalt)

Basalt, chiefly plagioclase feldspar and pyroxene, with possible olivine and secondary mineral infillings

Hag Stone

Perforated Sedimentary Rock (typically Flint, Chert, or Limestone)

Likely porphyritic igneous rock (possibly granite or rhyolite)

Quartz–feldspar–mica aggregate; exact identification requires a fresh surface and tests

Libyan Desert Glass

Impactite (vitreous silica), SiO2

Weathered gray metamorphic rock, likely phyllite or slate

Micaceous quartz–phyllosilicate rock; commonly quartz + muscovite/illite ± chlorite

Likely weathered quartz-rich rock fragment

Uncertain; possibly granitic pegmatite or quartz-bearing metamorphic rock

Rose Quartz

Rose Quartz (SiO₂)

Red-and-cream jasper

Jasper, an opaque microcrystalline variety of quartz (SiO₂), colored mainly by iron oxides

Rounded brown sandstone or weathered river cobble

Likely quartz-rich sandstone; exact identification requires a fresh surface and tests

Diamond (or Cubic Zirconia simulant)

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

Diamond

Carbon (C)

Quartz–mica metamorphic rock, likely schist

Quartz–muscovite/biotite schist; predominantly SiO₂ quartz with phyllosilicate micas

Weathered granite or granitic gneiss fragment

Coarse quartz–feldspar–mica aggregate; possibly weakly foliated gneiss

Chert / Flint

Cryptocrystalline Quartz (SiO2)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Chert (often referred to as Flint or Jasper when pigmented)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Chert (Flint Nodules)

Microcrystalline Quartz (SiO2)

Likely weathered basalt or mafic volcanic rock

Basalt; chiefly plagioclase feldspar, pyroxene, and commonly olivine or iron oxides

Rounded gray pebble

Indeterminate; likely a water-worn silicate or carbonate pebble

Sandstone

Arenite (clastic sedimentary rock)

Sandstone

Arenite (primarily Quartz-rich)

Sandstone

Arenite

Sandstone

Clastic Sedimentary Rock (primarily Quartz, SiO2)

Basalt with Mineral Vein (Cobble)

Basalt (with likely Quartz/Calcite vein)

Sodalite

Sodalite (Na8(Al6Si6O24)Cl2)

Sandstone

Arenite (SiO2 primarily)

Polished turquoise

Turquoise — hydrated copper–aluminum phosphate, CuAl₆(PO₄)₄(OH)₈·4H₂O

Tumbled blue chalcedony (likely blue quartz/chalcedony)

Cryptocrystalline silica, SiO₂; likely chalcedony, possibly dyed or surface-coated

River Pebble (Siltstone / Fine Sandstone)

Sedimentary Rock (siliciclastic clastic rock)

Black Onyx

Silicon Dioxide (SiO2) - Chalcedony variety

Agate

Agate (Silicon Dioxide, SiO2)

River Stone (likely Mudstone or Siltstone)

Lutite (Clastic sedimentary rock composed of clay and silt-sized particles)

Citrine

Silicon dioxide (SiO2)

Sandstone (Quartzose)

Arenite (composed primarily of SiO2)

Tumbled carnelian agate

Cryptocrystalline chalcedony (SiO₂), an iron-colored variety of agate

Citrine

Silicon Dioxide (SiO2)

Golden Calcite

Calcium Carbonate (CaCO3)

Quartz-rich vein rock, likely milky quartz in weathered host rock

Milky quartz (SiO₂), probably with weathered feldspar and iron-oxide staining

Sandstone

Clastic Sedimentary Rock

Weathered vesicular stone, possibly pumice or scoria

Vesicular volcanic rock; likely pumice (highly vesicular rhyolitic material) or scoria (basaltic material)

Chert (Flint)

Chert (Microcrystalline Quartz, SiO2)

Sandstone

Arenite