Anthropogenic (Man Made Material Processed By Nature)

Likely polished black stone or obsidian

Obsidian (volcanic glass), chiefly SiO₂

Citrine

Silicon Dioxide (SiO2) with iron impurities

Milky quartz (likely quartzite or massive quartz)

Quartz, silicon dioxide (SiO₂)

Iron-rich jasper / hematite-bearing breccia

Ferruginous jasper, chiefly microcrystalline SiO₂ with hematite/goethite (Fe₂O₃/FeO(OH)) and possible limonite

Milky quartz (rough quartz crystal)

Quartz, silicon dioxide (SiO₂)

Quartzite

Quartzite (SiO2)

Banded Sedimentary Rock (Wishbone Stone / Banded Quartzite or Limestone)

Silicified limestone or banded sedimentary rock with mineral veins

Polished mahogany obsidian (likely)

Volcanic glass; primarily silica-rich rhyolitic glass (SiO₂), with iron oxides

Rounded flint or chert pebble

Microcrystalline quartz (SiO₂), commonly chalcedony with possible impurities

Quartzite River Rock

Quartzite (primarily SiO2)

Polished jasper/chalcedony pebble

Microcrystalline quartz (SiO₂), likely brecciated or iron-stained jasper

Tumbled carnelian/chalcedony

Microcrystalline quartz (SiO₂), likely iron-stained chalcedony

Rough Quartz (Alluvial Pebbles)

Silicon Dioxide (SiO2)

Pale green translucent mineral fragment

Indeterminate; possibly fluorite, calcite, or glassy quartz

Tumbled blue chalcedony (likely common blue quartz)

Microcrystalline quartz, SiO₂; chalcedony variety

Chert (Flint variety)

Chert (Cryptocrystalline Quartz, SiO2)

Tumbled or rough turquoise-like specimen

Turquoise, hydrated copper aluminum phosphate — CuAl₆(PO₄)₄(OH)₈·4H₂O; identification is uncertain from the image

Vesicular basalt (likely weathered lava rock)

Vesicular basalt; primarily plagioclase feldspar, pyroxene, and volcanic glass, with possible iron-oxide alteration

Amygdaloidal Basalt

Basalt with secondary mineral infillings (SiO2, (Ca,Na)2-3(Mg,Fe,Al)5Si8O22(OH)2)

Serpentinite

Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)3(Si, Al, Fe)2O5(OH)4

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2)

Conglomeratic sandstone or breccia

Lithic arkose / polymictic conglomeratic sandstone

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

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

Rounded pale quartz-rich pebble

Likely milky quartz or quartzite (SiO₂); exact identification is uncertain from the photograph

Iron-stained limestone or coral fragment

Calcite-rich carbonate rock; chiefly CaCO₃ (exact identification is uncertain from the image)

Polished carnelian jasper / brecciated jasper

Microcrystalline quartz (SiO₂), chalcedony with iron-oxide pigments and opaque jasper fragments

Tumbled jasper (likely ocean or orbicular jasper)

Microcrystalline quartz (chalcedony), SiO₂, with iron oxides and dark accessory minerals

Fossil shark teeth

Probably fossilized shark teeth, possibly *Otodus* or *Carcharhinus* species

Dyed Quartz Geode

Silicon Dioxide (SiO2) with artificial pigment

Black Onyx

Cryptocrystalline Quartz (SiO2)

Diamond (in a jewelry setting)

Carbon (C)

Black Chert

Chert (microcrystalline quartz)

Aura Quartz Bead

Silicon dioxide (SiO2) with metal coating

Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Polished banded agate slab or agate-look decorative stone

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

Tumbled amethyst with possible lepidolite/colored quartz companion

Amethyst, purple quartz (SiO₂), likely with iron-related color centers

Pyrite (Fool's Gold)

Iron Disulfide (FeS2)

White quartz pebble (likely milky quartz)

Quartz, silicon dioxide (SiO₂)

Jasper

Jasper (Silica/Silicon Dioxide, SiO2)

Tumbled basalt (likely)

Basalt; fine-grained mafic volcanic rock composed mainly of plagioclase feldspar and pyroxene, often with minor olivine and iron oxides

Brecciated jasper

Silica-rich cryptocrystalline quartz (SiO₂), commonly with iron-oxide and clay-rich matrix

Fossilized coral or porous marine limestone

Likely fossil coral (Scleractinia), composed mainly of calcite/aragonite (CaCO₃)