Sedimentary Rock (Specifically A Concretion Or Possibly A Geode)

Chert (Jasper)

Microcrystalline Quartz (SiO2) with iron oxide impurities

Pebble

Lithic fragment / Weathered rock fragment

Fossil Coral

Coral Limestone (a type of biogenic sedimentary rock)

Sandstone (with Possible Iron Staining/Crust)

Arenite (SiO2 based)

Dalmatian Stone

Dalmatian Jasper (Aplitic Rock)

Rounded gray sandstone or siltstone cobble

Lithified quartz–feldspar–clay sediment; exact petrographic identification requires testing

Amethyst

Amethyst (Silicon Dioxide - SiO2 with impurities of iron)

Ironstone Concretion

Siderite or Hematite-rich Concretion (FeCO3 / Fe2O3)

Iron Ore / Hematite / Ironstone Nodule

Hematite / Goethite (Fe2O3 / FeO(OH))

Quartz (Druzy)

Silicon Dioxide (SiO2)

Quartz Geode Pebble

Silicon Dioxide (SiO2)

Ironstone / Limonite Concretion

Hydrated Iron Oxide Rock (FeO(OH)·nH2O with SiO2)

Pyrite-rich Ore

Pyrite (FeS2) with secondary minerals

Sandstone Pebble

Arenite (specifically Lithic or Quartz Arenite)

Pebble

Lithic fragment (Quartzite or general rock pebble)

Celestine (Celestite)

Strontium sulfate (SrSO4)

Basalt

Basalt (Mafic volcanic rock)

Druzy Quartz on Sandstone

Silicon Dioxide (SiO2) on Sedimentary Host Rock

Small rounded pebble

Indeterminate lithic grain; likely weathered sandstone, iron-stained quartz-rich rock, or a concretion

Dyed Agate Geode

Silicon Dioxide (SiO2) - Chalcedony variety

Ironstone Concretion (Limonite/Goethite)

Ferruginous Siltstone / Limonite Concretion (FeOO(OH)·nH2O)

Agate (Banded Chalcedony)

Cryptocrystalline Silica (SiO2)

Geode

Quartz / Chalcedony nodule

Rounded weathered stone, likely quartz-rich sandstone or iron-stained quartzite

Indeterminate; probable quartz (SiO₂)-rich clastic rock with iron-oxide staining

Sandstone

Arenite (primarily Quartz Arenite)

Septarian Nodule

Septarian Concretion (CaCO3-rich mudstone with Calcite/Aragonite veins)

Dark shale or slate fragment

Carbonaceous shale, possibly low-grade slate; composition mainly clay minerals, quartz, and organic carbon

Quartz Druzy (Geode Fragment)

Silicon Dioxide (SiO2)

Celestine (or Celestite) on Matrix

Celestine (SrSO4)

Concrete

Anthropogenic Conglomerate

Fossiliferous limestone pebble

Bioclastic limestone, primarily calcite (CaCO₃)

Basalt with Vesicular Texture

Aphanitic Mafic Igneous Rock (primarily Plagioclase and Pyroxene)

Druzy Quartz on Matrix

Silicon Dioxide (SiO2)

Chert (Flint)

Silicon Dioxide (SiO2)

Quartz Druze on Matrix

Silicon Dioxide (SiO2)

Celestite

Celestine (Strontium Sulfate, SrSO4)

Fossiliferous Limestone or Shale

Biomicrite (if limestone) or Fossiliferous Shale

Fossiliferous Limestone (Chert/Clay mixed)

Calcium Carbonate (CaCO3) / Silicon Dioxide (SiO2)

Banded Agate (specifically Eye Agate / Chalcedony)

Agate (Cryptocrystalline variety of Quartz, SiO2)

Dyed Blue Agate

Silicon Dioxide (SiO2) with artificial pigment

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Polymictic conglomerate or breccia (possibly concrete-like aggregate)

Lithified polymictic gravel; clasts may include basalt, granite, quartzite, and other silicates