Rock (Likely Sedimentary)

Chert (often called Flint or River Stone)

Chert (SiO2)

Jasper

Microcrystalline Quartz (SiO2)

Fossilized Gastropod Shell

Gastropoda (Class) replacement / internal cast (steinkern)

Chert / Flint Nodule

Microcrystalline quartz (SiO2)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Conglomerate

Polymictic Conglomerate

Fossil Shark Tooth

Lamniform (Mackerel Shark) fossil tooth, likely Otodus or Cretalamna

Quartzite with Vugs

Metamorphosed Quartz Sandstone (SiO2)

Sandstone

Arenite

Likely raw labradorite-bearing feldspar

Labradorite, plagioclase feldspar (approximately NaAlSi₃O₈–CaAl₂Si₂O₈)

Quartz Geode

Silicon Dioxide (SiO2)

Blue Agate (Tumbled and Dyed)

Silicon Dioxide (SiO2) with likely organic dyes

Chert / Quartz Pebble

Silicon Dioxide (SiO2)

Sandstone (with Iron Staining)

Clastic sedimentary rock (primarily SiO2 with Fe2O3 oxides)

Weathered granite or granitic gneiss fragment

Granite; chiefly quartz, alkali feldspar, plagioclase, and minor mica/iron oxides

Quartz Pebble

Silicon dioxide (SiO2)

Black-and-copper polished granite

Biotite granite, likely a commercial gabbro/granite variety

Serpentinite (likely serpentine-rich metamorphic rock)

Serpentine-group minerals, chiefly antigorite, lizardite, and/or chrysotile; commonly derived from altered peridotite

Metaconglomerate

Protolith: Conglomerate (comprising SiO2, Al2O3, etc.)

Likely weathered granite or granitic gneiss

Granite; quartz–feldspar–mica aggregate (possibly foliated gneiss)

Tumbled carnelian (likely chalcedony)

Carnelian, orange-red cryptocrystalline quartz (SiO₂), a variety of chalcedony

Druzy Quartz on Chert/Siltstone

Silicon Dioxide (SiO2) on Microcrystalline Silica/Siltstone matrix

Sandstone (Tumbled / Rounded)

Sedimentary Rock (Quartz arenite)

Weathered Sedimentary Rock with Liesegang Rings

Sandstone or Siltstone with Iron Oxide Banding

Greenish-gray quartz-rich rock, possibly weathered granite or quartzite

Provisional identification: quartz–feldspar aggregate; exact species cannot be confirmed from one photograph

Sandstone

Arenite (SiO2 based with various mineral cements)

Polished orbicular jasper (likely ocean jasper)

Jasper, microcrystalline quartz (SiO₂), colored by iron oxides and other inclusions

Polished pegmatitic granite (likely graphic granite)

Coarse-grained granitic rock composed chiefly of quartz, feldspar, and biotite/hornblende

Fossil-bearing Sedimentary Rock

Sedimentum cum fossili

Sandstone Pebble

Arenite (SiO2 dominated with iron oxide)

Granite

Phaneritic plutonic igneous rock (SiO2 range 65-75%)

Granite Pebble

Phaneritic Felsic Igneous Rock (primarily SiO2, KAlSi3O8, NaAlSi3O8)

Rugose Coral Fossil

Order Rugosa

Sandstone (Ferruginous)

Clastic sedimentary rock (SiO2 with Fe2O3)

Fossilized Bone

Vertebrate Fossil Fragment (Calcium Phosphate / Hydroxyapatite)

Sandstone (specifically Banded Sandstone)

Clastic sedimentary rock (primarily SiO2)

Banded agate (likely green jasper/agate pebble)

Microcrystalline quartz, SiO₂, with iron- and chlorite-rich inclusions

Shale with Siltstone layering

Sedimentary Clastic Rock (Mudstone/Shale)

Iron-rich weathered stone, possibly hematite-rich ironstone

Hematite/goethite-bearing ironstone; predominantly Fe₂O₃ and FeO(OH)

Weathered granite or granitic gneiss

Quartz–feldspar–mica granitic rock; possibly gneiss if foliation is present

Sandstone

Arenite (SiO2 predominantly)

Sandstone (Ferruginous)

Arenite (SiO2 with iron oxide impurities)