Tektite (Natural Glass)

Orange Quartz

Silicon Dioxide (SiO2) with iron oxide inclusions

Obsidian

Volcanic Glass (SiO2)

Tumbled pale quartz/chalcedony fragment

Quartz (SiO₂), possibly microcrystalline chalcedony

Tumbled jasper (likely ocean or orbicular jasper)

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

Dalmatian jasper

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

Quartz Pebble

Silicon Dioxide (SiO2)

Blue Lace Agate (Heat-treated/Crackle Quartz variety)

Silicon Dioxide (SiO2)

Beach Agate (Chalcedony)

Silicon Dioxide (SiO2)

Translucent agate/chalcedony

Microcrystalline quartz (SiO₂), likely chalcedony with agate-like banding

Aventurine

Silicon Dioxide (SiO2) with Fuchsite inclusions

Tiger's Eye, Hematite, and Black Obsidian Bracelet

SiO2 (Tiger's Eye), Fe2O3 (Hematite), and 70-75% SiO2 (Obsidian)

Milky quartz

Quartz, silicon dioxide (SiO₂)

Quartz-rich rock, possibly milky quartz or quartzite

Quartz (SiO₂), potentially quartzite if the grains are fused

Snowflake Obsidian

Volcanic glass containing Spherulites of Cristobalite (SiO2)

Quartzite Pebbles (River Stones)

Quartzite (primarily Silicon Dioxide, SiO2)

Amethyst cluster

Quartz, silicon dioxide (SiO₂), purple variety colored mainly by iron impurities and irradiation

Polished labradorite

Labradorite, calcium-rich plagioclase feldspar (approximately Ca0.5–0.7Na0.5–0.3Al1.5–1.7Si2.5–2.3O8)

Pink calcite (likely)

Calcite — calcium carbonate, CaCO₃

Milk Quartz (Sea Glass appearance)

Silicon Dioxide (SiO2)

Polished flint/chert pebble

Microcrystalline quartz (SiO₂), commonly called chert or flint

Quartz (Iron-stained)

Silicon Dioxide (SiO2)

Likely iron-rich slag or weathered ironstone

Hematite–goethite-rich material (Fe₂O₃/FeO(OH)); possibly industrial iron slag

Emerald

Beryl (Be₃Al₂Si₆O₁₈), specifically the green variety colored by trace amounts of chromium or vanadium.

Dark basalt or basaltic volcanic rock

Basalt, a fine-grained mafic volcanic rock composed mainly of plagioclase feldspar, pyroxene, and often olivine

Red Granite

Phaneritic Plutonic Felsic Rock (rich in Potassium Feldspar)

Dark rounded pebble, possibly basalt

Basalt (fine-grained mafic volcanic rock; identification tentative from photograph)

River Quartz

Quartz (Silicon Dioxide, SiO2)

Blue Agate (Dyed)

Silicon Dioxide (SiO2) - Variety of Chalcedony

Obsidian

Volcanic Glass (SiO2)

Green Banded Agate

Agate (Variety of Chalcedony/Quartz), SiO2

Obsidian

Obsidian (Extrusive Volcanic Glass)

Polished brown flint/chert (likely)

Microcrystalline quartz, SiO₂ (chalcedonic flint/chert)

Weathered sandstone or granitic rock fragment

Likely quartz-rich sandstone; exact identification requires testing

Tumbled citrine quartz (likely heat-treated amethyst)

Quartz, SiO₂; crystalline variety citrine

Sodalite beads

Sodalite, Na₈(Al₆Si₆O₂₄)Cl₂, likely with minor lazurite/pyrite or calcite inclusions

Slag

Metallurgical Slag

Quartzite River Rock

Metamorphic Quartzite (SiO2)

Jasper

Chert (Silica: SiO2)

Vesicular basalt (likely weathered lava rock)

Basalt; fine-grained mafic volcanic rock composed chiefly of plagioclase, pyroxene, and commonly olivine

Carborundum (Silicon Carbide)

Silicon Carbide (SiC)

Dyed blue howlite (turquoise imitation), possibly dyed magnesite

Howlite: Ca₂B₅SiO₉(OH)₅; the vivid blue color is artificial dye. Exact identification is uncertain from the photograph alone.

Pyrite in Matrix (Fool's Gold)

Iron Disulfide (FeS2)