Sedimentary Rock (Specifically A Concretion Or Possibly A Geode)

Weathered brown rock fragment

Indeterminate; possibly ferruginous sandstone or weathered volcanic rock

Fuchsite

K(Al,Cr)2(AlSi3)O10(OH)2

Polished orbicular jasper

Orbicular jasper; microcrystalline quartz (SiO₂) with hematite/goethite and other silicate inclusions

Amethyst (specifically Chevron Amethyst or Dream Amethyst)

Silicon Dioxide (SiO2) with iron impurities

Quartz Geode or Druzy Quartz on Matrix

Silicon Dioxide (SiO2)

Weathered quartz-rich rock, possibly chert or milky quartz

Mostly microcrystalline or crystalline quartz (SiO₂), identification uncertain from photograph

Quartz Crystal Cluster on Matrix

Silicon Dioxide (SiO2)

Stromatolite

Biogenic Sedimentary Rock (composed predominantly of CaCO3)

Botryoidal Agate

Silicon Dioxide (SiO2)

Ironstone Concretion

Ironstone (primarily Siderite or Limonite)

Sandstone (Pebble/Conglomerate fragment)

Sandstone (clastic sedimentary rock)

Sandstone (Ferruginous)

Arenite (primarily SiO2 with Fe2O3 staining)

Chert (Jasper)

Silicon Dioxide (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Likely chlorite-bearing schist (possibly greenschist)

Chlorite–quartz–mica schist; commonly contains muscovite/biotite and feldspar

Polished jasper pebble

Jasper, microcrystalline quartz (SiO₂) with iron-oxide and clay-mineral impurities

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Red Jasper with Quartz

Microcrystalline Quartz (SiO2)

Amethyst (Ametrine or Bicolor Quartz variant)

Silicon Dioxide (SiO2) with iron impurities

Sandstone with trace fossil

Sandstone, possibly with Skolithos or similar trace fossil

Ironstone Concretion / Goethite-Hematite Nodule

Goethite/Hematite (α-FeO(OH) / Fe2O3)

Basalt River Pebble

Aphanitic Mafic Basalt

Sandstone Pebble

Arenite (specifically Lithic or Quartz Arenite)

Quartz geode

Crystalline quartz, silicon dioxide (SiO₂), lining a volcanic geode

Ironstone Concretion

Ferruginous Siltstone/Ironstone (Fe2O3)

Quartz Pebble

Silicon Dioxide (SiO2)

Septarian Nodule

Septarian Concretion (CaCO3, CaMg(CO3)2, SiO2)

Limestone ( weathered ) / Chert Nodular Rock

Sedimentary rock (primarily Calcium Carbonate, CaCO3, with Microcrystalline Quartz, SiO2)

Tumbled quartz-rich pebble

Microcrystalline quartz (SiO₂), possibly weathered chert or chalcedony

Chalcedony (Agate/Carnelian variant)

Silicon Dioxide (SiO2)

Celestine

Celestine (Strontium Sulfate, SrSO4)

Chert / Jasper

Microcrystalline Quartz (SiO2)

Yellow Calcite

Calcium Carbonate (CaCO3)

Chert (Black Flint)

Silicon Dioxide (SiO2)

Sandstone (Ferruginous)

Arenite with Iron-Oxide cement

Chalcedony

Cryptocrystalline Quartz (SiO2)

Metallic sulfide ore, likely pyrite-bearing rock

Pyrite (FeS₂), possibly with chalcopyrite and quartz/host rock

Quartz (Herkimer Diamond variant)

Silicon Dioxide (SiO2)

Sandstone Pebble with Mineral Encrustation

Quartz Sandstone with Calcite/Halite Crust

Jasper with Quartz inclusion

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Chert (specifically Jasper)

Silicon dioxide (SiO2) with iron oxide inclusions

Banded calcite (likely marble or calcite-rich limestone)

Calcite, CaCO₃; possibly calcitic marble