Sedimentary Rock (Specifically A Concretion Or Possibly A Geode)

Sandstone Concretion

Clastic Sedimentary Concretion (typically Quartz/Silica with Iron Oxide)

Sparkling Druzy Quartz on Matrix

Silicon Dioxide (SiO2) with iron oxide inclusions

Foliated Metamorphic Rock (likely Gneiss or Schist)

Gneissic Metamorphic Rock

Quartz (Rock Crystal) with minor impurities

Quartz (SiO2)

Septarian Nodule Segment (Turtle Stone)

Septarian Concretion (CaCO3 with Siderite or Calcite infill)

Gneiss (specifically a granitic gneiss cobble)

Gneiss (high-grade regional metamorphic rock)

Tree Agate

Silicon Dioxide (SiO2) with Chlorite inclusions

Chert

Silicon dioxide (SiO2)

Dalmatian Stone

Dalmatian Jasper (Aplitic Rock)

Granite Gneiss

Gneiss (derived from granitic protolith)

Amethyst

Amethyst (Silicon Dioxide - SiO2 with impurities of iron)

Crazy Lace Agate

Chalcedony (Silicon Dioxide, SiO2)

Quartz Geode

Silicon Dioxide (SiO2)

Quartz Druse (on Chalcedony/Agate base)

Silicon Dioxide (SiO2)

Picture Jasper

Silicon Dioxide (SiO2) with iron oxide inclusions

Quartz Pebble

Silicon Dioxide (SiO2)

Pink Granite

Phaneritic Plutonic Felsic Igneous Rock (Granite)

Limonite Concretion

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

Limonite (Ironstone Concretion)

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

Septarian Nodule

Siderite or Calcite Concretion

Septarian Nodule or Mud Crack Fossil

Septarian Nodule (Concretion)

Moqui Marble

Iron Oxide Concretion

Banded Iron Formation (BIF)

Banded Iron Formation

Blue Celestite (with Galena)

Strontium sulfate (SrSO4) and Lead sulfide (PbS)

Sandstone (with ripple marks)

Arenite / Quartz Sandstone

Jasper Conglomerate (Puddingstone)

Siliceous Conglomerate (Quartz and Jasper clasts in a fine-grained matrix)

Red Jasper

Jasper (Silica/Silicon Dioxide, SiO2 plus iron inclusions)

Citrine

Crystalline Quartz (SiO2) with iron impurities

Sandstone (lithic/greywacke variety)

Arenite (composed primarily of SiO2 with various lithic fragments)

Sandstone Beach Pebble

Clastic Sedimentary Rock (primarily Quartz with Iron Oxide coating)

Ironstone Concretion / Goethite-Hematite Nodule

Goethite/Hematite (α-FeO(OH) / Fe2O3)

Quartz Geode (Druzy)

Crystalline Silicon Dioxide (SiO2)

Chalcedony

Cryptocrystalline Quartz (SiO2)

Amethyst Geode

Silicon Dioxide with impurities (SiO2)

Glauconitic Sandstone (Greensand)

Glauconitic Sandstone ((K, Na)(Fe3+, Al, Mg)2(Si, Al)4O10(OH)2)

Ferruginous Sandstone

Sandstone (rich in iron oxides/hydroxides)

Chert (Flint variety)

Chert (SiO2)

Red Jasper (possibly Red Coral or dyed Howlite)

Silicon Dioxide (SiO2) with Iron Oxide inclusions

BROWN GRANITE (likely 'Tan Brown' or similar)

Granite (specifically a variety rich in orthoclase feldspar, often with biotite and possibly hornblende)

Druzy Quartz (on Geode Fragment)

Silicon Dioxide (SiO2)

Clear Quartz

Silicon dioxide (SiO2)

Sandstone Concretion with Fossil Wood

Ferruginous Sandstone Concretion (SiO2 with Fe2O3 cement)