Rock (Likely Sedimentary)

Basalt (Volcanic Peak)

Extrusive Mafic Igneous Rock

Granitoid (Granite/Gneiss mix)

Phaneritic Felsic Igneous Rock

Granite Pebble

Granite (Felsic Plutonic Rock)

Basalt (Lava Rock) and Dyed Glass/Quartz

Scoria (Vesicular Basalt)

Quartzite River Rock (with iron staining)

Metamorphosed Sandstone (SiO2)

Pumice

Vesicular volcanic glass

Quartzite

Metamorphic Quartz (SiO2)

Weathered granite (likely biotite granite)

Granite; interlocking quartz, feldspar, and mica, commonly with biotite

Granite Pebble

Phaneritic plutonic rock (Quartz-Alkali Feldspar-Plagioclase)

Vesicular basalt (likely weathered lava rock)

Basalt, predominantly calcium-rich plagioclase, pyroxene, and commonly olivine; vesicular texture from gas bubbles

Green Chert (Jasper)

Silicon Dioxide (SiO2)

Iron-rich meteorite candidate

Unclassified stony-iron or iron meteorite fragment

Iron-stained quartz-rich rock, possibly quartzite or hydrothermal quartz

Quartz (SiO₂), likely with iron oxides; exact host rock uncertain from the photograph

Fossil Shark Tooth

Elasmobranchii (Lamniformes order likely)

River Rock / Stream Pebble

Fluvial Clast / Rounded Sedimentary Particle

Granite Cobble

Phaneritic plutonic rock (dominated by Quartz, Feldspar, and Mica)

Dark rounded pebble, likely basalt or volcanic rock

Fine-grained mafic igneous rock; possibly basalt (composition chiefly plagioclase and pyroxene)

Granite Pebble

Granite (Phaneritic intrusive igneous rock)

Weathered granitic rock

Granitoid, likely biotite granite or granodiorite

Milky quartz vein fragment

Quartz, silicon dioxide (SiO₂)

Tooth or shell fragment (likely fossilized marine material)

Indeterminate; possibly a fossil fish tooth or mollusk shell fragment composed mainly of calcium carbonate (CaCO₃)

Limonite (Ironstone Concretion)

Limonite (Hydrated iron(III) oxide-hydroxide, mixtures of FeO(OH)·nH2O)

Likely basalt pebble

Basalt; fine-grained mafic volcanic rock, chiefly plagioclase and pyroxene with possible olivine

Rounded sandstone cobble

Quartz-rich sandstone, likely ferruginous litharenite

Agate Geode

Silicon Dioxide (SiO2) - Chalcedony variety

Pumice (specifically a water-worn, weathered variety)

Vesicular volcanic glass

Chert (Flint)

Microcrystalline Quartz (SiO2)

Tumbled quartz-rich stone, possibly blue quartz or granite

Quartz (SiO₂), with probable feldspar and dark accessory minerals

Milky Quartz (Gold-bearing Prospecting Specimen)

Silicon Dioxide (SiO2)

Milky Quartz

Quartz (Silicon Dioxide - SiO2)

Quartz (specifically Milky/Gray Quartz vein)

Silicon Dioxide (SiO2)

Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Basalt (Weathered River Stone)

Basalt (Extrusive Mafic Igneous Rock)

Basalt (Crushed Stone)

Basalt (Mafic Extrusive Igneous Rock)

Chalcedony (Agate Pebble)

Microcrystalline Quartz (SiO2)

Reddish-brown granitic pebble

Granite, likely biotite granite or granodiorite

Quartz Pebble

Silicon Dioxide (SiO2)

Bicolor Quartz Pebble

Silicon Dioxide (SiO2) with mineral inclusions

Likely quartzite pebble

Quartzite, predominantly crystalline SiO₂

Dark mafic igneous rock, likely basalt or gabbro

Basalt–gabbroic rock; mainly plagioclase feldspar and pyroxene, possibly olivine or magnetite

Quartz-rich rock, likely milky quartz or quartzite

Quartz (SiO₂); possibly quartzite, a recrystallized quartz sandstone

Green-and-white quartz-rich rock, likely chrysoprase or serpentine-bearing stone

Uncertain; possible chrysoprase (microcrystalline quartz, SiO₂) or serpentinite (magnesium silicate minerals)