Igneous Rock (Volcanic Glass)

Beach Pebble (Basalt/Greywacke)

Amygdaloidal Basalt

Granodiorite (Riverbed Cobble)

Granodiorite

Black Obsidian

Volcanic Glass (70–75% SiO2 plus MgO, Fe3O4)

Jasper in Rhyolite matrix

Silicon Dioxide (SiO2) with various inclusions in Felsic Igneous matrix

Grey Granite

Phaneritic Felsic Igneous Rock (primarily Quartz, Feldspar, and Mica)

Weathered vesicular stone, possibly pumice or scoria

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

Basalt

Extrusive Mafic Igneous Rock (composed primarily of plagioclase feldspar and pyroxene)

Carnelian Agate

Carnelian (SiO2 with iron oxide impurities)

Clear quartz sphere

Quartz (silicon dioxide, SiO₂)

Greenstone

Greenschist / Greenstone (containing Chlorite, Epidote, Actinolite)

Milky Quartz

Silicon Dioxide (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Diorite (Salt and Pepper Rock)

Diorite

Garnet

Almandine/Pyrope Garnet (Silicate Mineral Group)

Basalt

Mafic Volcanic Rock (primarily Plagioclase and Pyroxene)

Dark gray river pebble, likely basalt or mudstone

Tentatively fine-grained basalt (plagioclase–pyroxene), though the image cannot exclude mudstone or weathered andesite

Quartz Vein / Milky Quartz

Silicon Dioxide (SiO2)

Obsidian

Obsidian (Volcanic Glass, SiO2 + impurity isotopes)

Basalt

Basalt

Banded Agate (specifically Carnelian Agate slice)

Chalcedony (cryptocrystalline variety of Quartz), SiO2

Mahogany Obsidian

Volcanic Glass with Hematite/Magnetite inclusions

Quartz Geode with Calcite

Silicon Dioxide (SiO2) with Calcium Carbonate (CaCO3)

Black Obsidian

Obsidian (Volcanic Glass, ~70% SiO2)

Green Jasper

Silicon Dioxide (SiO2) with iron silicate inclusions

Obsidian

Obsidian (Volcanic glass), SiO2 (70% or more)

Moss Agate

Silicon Dioxide (SiO2) with inclusions of Manganese or Iron oxide

Milky Quartz

Silicon Dioxide (SiO2)

Yellow Quartz (Citrine or Yellow Jasper)

Silicon Dioxide (SiO2)

Vesicular Basalt

Vesicular Basalt (Aphanitic Mafic Rock)

Smoky Quartz on Feldspar (Granite Pegmatite)

Silicon Dioxide (SiO2) with Potassium Aluminum Silicate (KAlSi3O8)

Basalt

Basalt (Composition primarily Plagioclase feldspar, Pyroxene, and Olivine)

Mahogany Obsidian

Volcanic Glass with Hematite or Magnetite (SiO2 + Fe2O3)

Obsidian

Obsidian (Amorphous volcanic glass, SiO2 rich)

Massive Quartz

Silicon dioxide (SiO2)

Scoria (Lava Rock)

Scoriaceous Basalt

Quartz Pebble

Silicon Dioxide (SiO2)

Native Copper in Basalt

Cu-element in Mafic Volcanic Rock (Basalt)

Quartz (Milky or Smoky Quartz)

Silicon Dioxide (SiO2)

Vesicular Basalt Pebble

Basalt

Milky Quartz

Silicon Dioxide (SiO2)

Porphyritic polymictic breccia (likely volcanic breccia)

Volcanic breccia; probable polymictic andesite–dacite breccia with quartz/feldspar clasts

Basalt

Basalt (primarily composed of Plagioclase feldspar and Pyroxene)