Metamorphic Rock (Specifically A Rock Composed Of Minerals)

Clear Quartz (Rock Crystal)

Quartz (Silicon Dioxide, SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Basalt with Plagioclase Phenocrysts

Porphyritic Basalt (primarily SiO2, MgO, FeO, and CaO)

Porphyritic Basalt

Amygdaloidal Porphyritic Basalt

Porphyritic Andesite

Andesite

Quartzite Pebble

Quartzite (primarily SiO2)

Mica Schist

Mica Schist (primarily Muscovite or Biotite KAl2(AlSi3O10)(OH)2)

Mahogany Obsidian

Volcanic Glass with Hematite/Magnetite (SiO2 + Fe2O3)

Chert (Black Chert/Flint)

Chert (Silicon Dioxide, SiO2)

Banded Agate Geode

Silicon Dioxide (SiO2)

Flower Agate

Chalcedony (Silicon Dioxide, SiO2) with Opaque Spherulitic Inclusions

Chert (often called Flint when dark)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Quartzite Pebble (River Rock)

Metamorphic Quartzite (predominantly SiO2)

Mica Schist

Crystalline Schist (often primarily Muscovite or Biotite sheet silicates)

Quartzite

Quartzite (SiO2 silicon dioxide)

Basalt

Mafic volcanic rock (various silicate minerals including Pyroxene and Plagioclase)

Quartzite River Stone

Quartzite (primarily SiO2)

Garnet (specifically Almandine)

Almandine (Fe3Al2(SiO4)3)

Coal (most likely Bituminous or Anthracite)

Coal (primarily composed of carbon with varying amounts of other elements)

Granite

Phaneritic Plutonic Felsic Rock (Granite)

Quartzite

Quartzite (SiO2)

River Cobble (likely Sandstone or Siltstone type)

Sandstone or Siltstone (common rock types that form river cobbles)

Quartz (River Pebble)

Silicon Dioxide (SiO2)

Smoky Quartz

Silicon Dioxide (SiO2)

Basalt with Quartz/Calcite Veins

Amygdaloidal Basalt (SiO2 or CaCO3 inclusions)

Orbicular Rhyolite (Rainforest Jasper)

Rhyolite containing Spherulites (SiO2 with impurities)

Quartzite

Quartzite (SiO2)

Quartzite Pebble (River Rock)

Quartzite (primarily SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Quartzite

Quartzite (composed primarily of SiO2)

Red Brecciated Jasper

Silicon Dioxide (SiO2) with Hematite inclusions

Diamond Drill Core (Greenschist and Quartzite)

Chlorite Schist / Meta-quartzite (Metamorphic Rock Core Sample)

Granitic Pegmatite

Granite Pegmatite (principally KAlSi3O8, SiO2, and KAl2(AlSi3O10)(OH)2)

River Pebble (Likely Quartzite or Gneiss)

Metamorphosed Silicate Rock (primarily SiO2)

Serpentine

Antigorite, Lizardite, or Chrysotile; (Mg,Fe,Ni,Al,Zn,Mn)2-3(Si,Al,Fe)2O5(OH)4

Quartzite Pebble

Metamorphosed Quartz Sandstone (SiO2)

Quartzite Pebbles (River Stones)

Quartzite (primarily Silicon Dioxide, SiO2)

Black Sand (Magnetite Sand)

Magnetite (Fe3O4)

Quartzite

Quartzite (primarily SiO2)

Agate (Common Chalcedony)

Silicon Dioxide (SiO2)