Sedimentary Rock (Specifically A Concretion Or Possibly A Geode)

Septarian Nodule

Septarian Concretion

Quartz Geode

Crystalline Silicon Dioxide (SiO2) within a geode structure

Agate (Carnelian / Chalcedony)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Weathered limestone or calcareous concretion

Calcite-rich carbonate rock; primarily CaCO₃

Quartz Druzy Geode Fragment

Silicon Dioxide (SiO2)

Banded Agate (Geode Fragment)

Silicon Dioxide (SiO2) - Variety Agate

Quartz Geode (partially opened)

Silicon Dioxide (SiO2) with iron staining

Likely quartz-rich gravel fragment (uncertain identification)

Quartz, silicon dioxide (SiO₂), possibly mixed with feldspar or other light-colored minerals

Quartz (Druzy)

Silicon Dioxide (SiO2)

Quartz Geode in Sedimentary Matrix

Silicon Dioxide (SiO2) within a limestone/dolostone host

Quartz Geode (partially filled/solid)

Silicon Dioxide (SiO2)

Foliated Metamorphic Rock (likely Gneiss or Schist)

Gneissic Metamorphic Rock

Hag Stone (Adder Stone / Geode-bearing Pebble)

Sedimentary Rock with Cavity (often Quartzite, Limestone, or Sandstone)

Iron-rich sandstone or weathered laterite

Ferruginous sandstone, composed mainly of quartz with iron-oxide cement (Fe₂O₃/FeOOH)

Dyed Blue Agate Slice

Silicon Dioxide (SiO2) - Variety Agate

Basalt (Greenstone)

Amygdaloidal Basalt / Chloritized Basalt

Basalt (Vesicular)

Extrusive mafic igneous rock; primarily (Ca, Na)(Mg, Fe, Al)(Si, Al)2O6 with (Ca, Na)(Al, Si)4O8

Limestone (specifically Crushed Limestone/Calcictic)

Calcium Carbonate (CaCO3)

Unidentified Rock

Unknown

Iron-Oxide Concretion (Moqui Marble)

Goethite/Hematite Concretion (Fe2O3 / FeO(OH))

Quartz

Quartz (SiO2 - Silicon Dioxide)

Fossil fish impression or partial fish fossil

Indeterminate fossilized fish; likely compressed vertebrate remains in sedimentary rock

Weathered iron-rich concretion or limonite-bearing rock

Limonite/goethite-rich concretion; limonite is an iron-oxide/hydroxide mixture, commonly dominated by goethite (FeO(OH))

Sandstone Concretion

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

Jasper (Yellow Jasper)

Silicon Dioxide (SiO2) with iron inclusions

Polished blue-gray agate/geode slice (tentative)

Microcrystalline quartz (chalcedony), SiO₂, possibly with druzy quartz

Geode (Unopened)

Silica-lined Vug (primarily SiO2)

Chert (Flint)

Microcrystalline quartz (SiO2)

Druzy Quartz on Limestone

Silicon Dioxide (SiO2)

Iron-rich concretion or weathered ironstone

Limonite/goethite-rich iron oxide (hydrated FeO(OH)·nH₂O), possibly with hematite

Geode with Quartz and Chalcedony

Silicon Dioxide (SiO2)

Agate Geode Slice

Silicon Dioxide (SiO2) with trace elements

Omarolluk (Omar)

Siliceous greywacke with carbonate concretions

Small pale stone, likely quartzite or limestone fragment

Indeterminate; possible quartzite (mostly SiO₂) or calcitic limestone (CaCO₃)

Hag Stone

Perforated Sedimentary Rock (typically Limestone or Sandstone)

Agate Geode / Nodular Chalcedony

Silicon Dioxide (SiO2) with impurities

Amethyst on Matrix

Amethyst (Silicon Dioxide, SiO2) with impurities of iron and irradiation

Blue Chalcedony

Silicon Dioxide (SiO2)

Chert

Chert (SiO2)

Polished septarian nodule fragment

Septarian calcite–aragonite concretion in clay-rich limestone/mudstone

Chert (Yellow Jasper)

Microcrystalline Quartz (SiO2)

Quartz geode with iron-oxide matrix

Quartz (SiO₂), likely with limonite/goethite and possibly calcite