Limonite-stained Quartz / Quartzite rock specimen

Limonite-stained Quartz / Quartzite

Silicon Dioxide (SiO2) with iron hydroxides (FeO(OH)·nH2O)

sedimentary or metamorphic

Sandstone (likely Ferruginous) rock specimen

Sandstone (likely Ferruginous)

Arenite (SiO2 with iron oxide impurities)

sedimentary

Limonite Concretion rock specimen

Limonite Concretion

Limonite (FeO(OH)·nH2O)

sedimentary

Granite rock specimen

Granite

Phaneritic Plutonic Felsic Rock (SiO2, KAlSi3O8, NaAlSi3O8, CaAl2Si2O8)

igneous

Obsidian rock specimen

Obsidian

Obsidian (Volcanic Glass, SiO2 + impurities)

igneous

Sandstone (Quartzose) rock specimen

Sandstone (Quartzose)

Arenite (Siliciclastic sedimentary rock)

sedimentary

Quartz (Milky/Common) rock specimen

Quartz (Milky/Common)

Silicon Dioxide (SiO2)

mineral

Quartz Mineral rock specimen

Quartz Mineral

Silicon Dioxide (SiO2)

mineral

Quartzite (Gold/Yellow) rock specimen

Quartzite (Gold/Yellow)

Quartzite (SiO2)

metamorphic

Chert (Yellow Jasper variant) rock specimen

Chert (Yellow Jasper variant)

Microcrystalline Quartz (SiO2)

sedimentary

Quartz (Smoky/Milky variety with inclusion) rock specimen

Quartz (Smoky/Milky variety with inclusion)

Silicon Dioxide (SiO2)

mineral

Nephrite Jade rock specimen

Nephrite Jade

Nephrite (Ca2(Mg, Fe)5Si8O22(OH)2)

metamorphic

Quartz (Milky/Smoky variety) rock specimen

Quartz (Milky/Smoky variety)

Silicon Dioxide (SiO2)

mineral

Sandstone (with potential mineral inclusions) rock specimen

Sandstone (with potential mineral inclusions)

Clastic sedimentary rock (primarily Quartz, SiO2)

sedimentary

Pink Coral rock specimen

Pink Coral

Corallium rubrum (Calcium Carbonate, CaCO3)

mineral

Quartz rock specimen

Quartz

Silicon Dioxide (SiO2)

mineral

Chrysoprase rock specimen

Chrysoprase

Chalcedony (Silicon Dioxide, SiO2), flavored by Nickel

mineral

Dyed Agate / Painted Stone rock specimen

Dyed Agate / Painted Stone

Silicon Dioxide (SiO2) with artificial pigment

sedimentary (base), then artificial

Chert (Jasper/Flint variety) rock specimen

Chert (Jasper/Flint variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

sedimentary

Milky Quartz rock specimen

Milky Quartz

Silicon Dioxide (SiO2)

mineral

Obsidian rock specimen

Obsidian

Obsidian (Volcanic Glass, SiO2)

igneous

Red Sandstone rock specimen

Red Sandstone

Arenite (primarily Quartz, SiO2, with Iron Oxide/Hematite)

sedimentary

Fossiliferous Limestone rock specimen

Fossiliferous Limestone

Biogenic Limestone (Calcium Carbonate, CaCO3)

sedimentary

Clear Quartz rock specimen

Clear Quartz

Silicon Dioxide (SiO2)

mineral

Chert (often called Flint when dark) rock specimen

Chert (often called Flint when dark)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

sedimentary

Granite rock specimen

Granite

Granite (Felsic Plutonic Rock)

igneous

Sandstone (Wonderstone) rock specimen

Sandstone (Wonderstone)

Silicified Sandstone / Orthoquartzite with Liesegang rings

sedimentary

Basalt River Stones rock specimen

Basalt River Stones

Aphantic Mafic Igneous Rock (Basalt)

igneous

Diorite rock specimen

Diorite

Diorite (intermediate intrusive igneous rock)

igneous

Granite (Background) and Quartzite/River Pebble (Foreground Heart) rock specimen

Granite (Background) and Quartzite/River Pebble (Foreground Heart)

Phaneritic Felsic Igneous Rock (Granite background)

igneous

Quartzite with Iron Inclusions rock specimen

Quartzite with Iron Inclusions

Metamorphosed Sandstone (SiO2 dominated)

metamorphic

Quartz (Iron-stained) rock specimen

Quartz (Iron-stained)

Silicon Dioxide (SiO2)

mineral

Onyx (Black Onyx) rock specimen

Onyx (Black Onyx)

Silicon Dioxide (SiO2)

mineral

Yellow Quartz (Citrine or Quartz Crystal with Iron Inclusions) rock specimen

Yellow Quartz (Citrine or Quartz Crystal with Iron Inclusions)

Silicon Dioxide (SiO2)

mineral

Coral Fossil (Petrified Coral) rock specimen

Coral Fossil (Petrified Coral)

Scleractinia (Order) - Calcified Fossil Skeleton (CaCO3)

sedimentary

Basalt rock specimen

Basalt

Basalt (Mafic volcanic rock)

igneous

Chert (with Limestone matrix) rock specimen

Chert (with Limestone matrix)

Chert (Silica: SiO2)

sedimentary

Limestone (specifically Marl or Chalk) rock specimen

Limestone (specifically Marl or Chalk)

Calcium Carbonate (CaCO3)

sedimentary

Basalt rock specimen

Basalt

Basalt (Aphanitic Mafic Igneous Rock)

igneous

Quartz Pebble rock specimen

Quartz Pebble

Silicon Dioxide (SiO2)

mineral

Agate (Banded Chalcedony) rock specimen

Agate (Banded Chalcedony)

Agate (Silicon Dioxide, SiO2)

mineral

Sandstone rock specimen

Sandstone

Sandstone (Sedimentary rock composed of silicate grains)

sedimentary