Rock (Likely Sedimentary)

Likely basalt with a pale mineral-filled vesicle

Vesicular basalt, probably containing calcite or zeolite (uncertain from image)

Tumbled orange chalcedony (likely carnelian)

Microcrystalline quartz, SiO₂; iron-bearing variety commonly termed carnelian

Shale

Argillaceous Rock

Polished banded agate (likely sardonyx)

Cryptocrystalline chalcedony, SiO₂; reddish bands are iron-stained layers

Sandstone

Clastic sedimentary rock (primarily SiO2)

Chert (Jasper/Agate variety)

Microcrystalline Quartz (SiO2)

Sandstone (Ferruginous)

Arenite (with Iron Oxide cement)

Porphyritic Basalt or Porphyry

Porphyritic Extrusive Igneous Rock

Porphyritic Basalt

Basalt (Porphyritic texture)

Unidentified coarse-grained rock fragments

Likely granite or granitic rock; exact identification is uncertain from the photograph

Yellow Chalcedony (likely Carnelian or Yellow Agate)

Silicon Dioxide (SiO2)

Quartz Geode

Silicon dioxide (SiO2)

Porphyritic basalt (likely amygdaloidal basalt)

Basalt containing larger plagioclase crystals and pale vesicle-fill minerals, commonly calcite, zeolite, or quartz

Pyrite

Iron Sulfide (FeS2)

Sandstone

Arenite

Weathered granite (likely with accessory quartz)

Granite; chiefly quartz, K-feldspar, plagioclase, and biotite/hornblende

Polished jasper (likely brecciated or scenic jasper)

Microcrystalline quartz/chalcedony, SiO₂, with iron-oxide and other mineral inclusions

Polished green aventurine (likely)

Quartzite dominated by quartz (SiO₂), commonly containing fuchsite mica

Brown Chalcedony

Silicon Dioxide (SiO2)

Sandstone

Arenite

Sandstone

Arenite

Silty Shale

Silty Shale (Fissile Sedimentary Rock)

Shale (Ferruginous)

Laminated Mudrock (Siliciclastic Sedimentary Rock)

Shale

Mudstone (composed primarily of clay minerals like kaolinite, illite, and smectite, with quartz and calcite)

Sandstone (Water-worn pebble)

Arenite (primarily SiO2)

Bicolor Quartz (Milk Quartz with Slag or Dark Inclusions)

Silicon Dioxide (SiO2) with impurities

Quartz Druzy

Crystalline Silicon Dioxide (SiO2)

Raw greenish-blue quartz-bearing mineral specimen

Likely fluorite or chalcedony/quartz; exact identification requires hardness and crystal tests

Quartz

Quartz (SiO2 - Silicon Dioxide)

Quartz-veined Sedimentary Rock

Sedimentary rock with hydrothermal quartz veins

Petrified Wood Agate

Silicified Wood (primarily SiO2)

Weathered limestone

Calcitic limestone, mainly calcium carbonate (CaCO₃)

Chert (containing fossil leaf impression)

Microcrystalline silicon dioxide (SiO2)

Milky Quartz with Iron Inclusions

Quartz (Silicon Dioxide, SiO2)

Fossiliferous Limestone with Crinoid Stem Impression

Calcium Carbonate (CaCO3) matrix with Crinoidea fossil

Chalcedony (Agate/Chert variety)

Silicon Dioxide (SiO2)

Weathered flint or chert fragment

Microcrystalline quartz (SiO₂), likely chert/flint

Gypsum (Selenite crystals in Halite/Clay matrix)

Calcium Sulfate Dihydrate (CaSO4·2H2O)

Weathered fossiliferous limestone fragment, possibly fossil coral or shell material

Indeterminate carbonate fossil in calcitic limestone; likely composed mainly of calcite (CaCO₃), but species identification is not possible from this image alone

Agate (translucent water-worn pebble)

Cryptocrystalline Quartz (SiO2)

Yellow Jasper

Cryptocrystalline Quartz (SiO2) with iron inclusions

Chert (variations include Chalcedony and Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)