Not A Rock

Quartzite Pebble

Metamorphosed Quartz Sandstone (SiO2)

Epidote

Epidote Group (Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH))

Quartz (Milky or Cloudy variety)

Silicon Dioxide (SiO2)

Blue Lace Agate

Chalcedony (SiO2)

Blue Howlite (Dyed)

Calcium Borosilicate Hydroxide (Ca2B5SiO9(OH)5)

Chert Pebble

Microcrystalline quartz (SiO2)

Jasper Breccia

Silicon Dioxide (SiO2) with impurities

Chert (Iron-stained)

Microcrystalline Quartz (SiO2)

Chert (Chert Pebble)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Gneissic River Pebble

Gneiss

Glauconite (Greensand)

(K, Na)(Fe3⁰, Al, Mg)₂(Si, Al)₄O₁₀(OH)₂

Coquina Jasper

Fossiliferous Chalcedony (SiO2)

Sandstone Concretion

Clastic Sedimentary Concretion (SiO2 with Iron Oxide)

Chert (Commonly known as Jasper or Flint)

Microcrystalline Quartz (SiO2)

Concretion

Sedimentary Concretion (e.g., Siderite or Ironstone)

River Pebbles (Stream-rounded rocks)

Fluvial Detritus (varied mineralogy)

Sandstone (likely River-tumbled Picture Sandstone)

Arenite (predominantly SiO2 with iron oxide impurities)

Labradorite (Larvikite variety)

Plagioclase Feldspar (Na,Ca)(Al,Si)4O8 with Monzonite/Syenite matrix

Sandstone Concretion

Septarian or Carbonate-cemented Sandstone Concretion

Sodalite

Sodalite (Na8(Al6Si6O24)Cl2)

Quartzite Pebble

Metamorphosed Quartz Sandstone (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Porphyritic Basalt or Andesite

Porphyritic Basalt/Andesite

Sand Dollar Fossil

Echinoidea (Clypeasteroida)

Quartzite

Quartzite (primarily SiO2)

Petrified Wood

Silicified Wood (primarily SiO2 - Silicon Dioxide)

Ironstone Concretion

Limonitic/Hematitic Concretion

Quartz with Limonite Staining

Silicon Dioxide (SiO2) with Hydrated Iron Oxide (FeO(OH)·nH2O)

Garnet in Matrix (Eclogite)

Eclogite, featuring Almandine or Pyrope Garnet [X3Y2(SiO4)3]

Carnelian Agate

Silicon Dioxide (SiO2) - variety of Chalcedony

Dyed Agate

Chalcedony (Silicon Dioxide, SiO2)

Bumblebee Jasper

Volcanic Tuff (mixture of Quartz, Sulfur, Hematite, and Orpiment)

Limonite (Iron Ore)

FeO(OH)·nH2O (Hydrated iron(III) oxide-hydroxide)

Amygdaloidal Basalt

Amygdaloidal Basalt (Mafic volcanic rock including secondary mineral infills)

Porphyritic Basalt (Porphyry)

Porphyritic Basalt

Amethyst (Agate/Chalcedony variety)

Silicon Dioxide (SiO2) with iron impurities

Amethyst

Quartz (Silicon Dioxide) - SiO2 with Iron impurities

Sandstone Concretion

Clastic Sedimentary Concretion (primarily SiO2 with Fe2O3 cement)

Chert (Yellow Jasper/Flint)

Microcrystalline Quartz (SiO2)

Banded Agate

Chalcedony (SiO2) with impurities