Organic (Geological Interest)

Petoskey Stone

Hexagonaria percarinata (Fossilized Rugose Coral)

Quartz-veined Sandstone Pebble

Quartzite-veined Arenite

Moqui Marble / Ironstone Concretion

Ironstone Concretion (Goethite/Hematite and Sandstone)

Fulgurite

Fulgurite (Lechatelierite-rich fused silica)

Quartz Vein in Siltstone

SiO2 (Quartz) on clastic sedimentary matrix

Gold Ore (in Quartz/Sulfide matrix)

Native Gold (Au) in Quartz (SiO2) and Pyrite (FeS2)

Sandstone with Trace Fossils

Arenite with Ichnofossils

Small pale stone fragment (undetermined)

Unidentified; the image lacks diagnostic detail for a reliable identification

Fossilized Wood (Petrified Wood)

Silicified Wood (primarily quartz/chalcedony replacing organic matter)

Chert / Flint

Chert (Microcrystalline Quartz, SiO2)

Fossilized coral (possible)

Indeterminate fossil; the image does not show enough diagnostic detail to identify a taxon

Earthy Siltstone with Iron Staining

Siltstone / Argillite with Goethite/Hematite inclusions

Limonite on Sandstone

Iron Oxyhydroxide (FeO(OH)·nH2O) on Quartz Sandstone

Biotite Schist

Biotite Mica Schist

Puddingstone

Conglomerate (Silicon Dioxide - SiO2 with various inclusions)

Chert Breccia

Brecciated Chert

Likely iron-rich sandstone or ironstone pebble

Ferruginous sandstone (quartz-rich sandstone cemented by iron oxides); exact identification requires testing

Ironstone Concretion (Limonite/Goethite)

Ironstone (composed primarily of Goethite FeO(OH) and Limonite)

Amygdaloidal Basalt

Basalt with secondary amygdule minerals (likely Epidote or Chlorite)

Sedimentary rock with quartz veining

Laminated siltstone or mudstone with hydrothermal quartz veins

Quartz Vein in Host Rock

Silicon Dioxide (SiO2)

Fossil oyster shell

Fossilized bivalve, likely an oyster (family Ostreidae); exact genus and age are indeterminable from the image

Chert (Nodule)

Microcrystalline Quartz (SiO2)

Basalt

Basalt (extrusive volcanic rock)

Gossan (Iron Hat)

Limonitic Gossan (Fe2O3·nH2O)

Vesicular Basalt

Vesicular Basalt

Bituminous coal

Coal, predominantly carbon with macerals and minor clay/pyrite minerals

Conglomerate

Conglomerate (clastic sedimentary rock)

Small fossil shell fragment, likely a foraminiferal or other marine microfossil

Unidentified calcareous fossil; exact taxon cannot be determined from the image

Ironstone concretion (possibly a pyrite-bearing concretion)

Iron-oxide-cemented sedimentary concretion; exact mineral composition cannot be confirmed from the photograph

Weathered quartz-bearing rock

Likely quartz-veined schist or gneiss; exact identification is uncertain from the image

Weathered granite boulder

Granite, a coarse-grained felsic intrusive igneous rock composed mainly of quartz, feldspar, and mica

Porphyritic granite (likely weathered granitic rock)

Granite; chiefly quartz, alkali feldspar, plagioclase, and biotite/hornblende

Limonite (Limonitic Sandstone)

Hydrated Iron(III) Oxide-Hydroxide ($FeO(OH)·nH_2O$)

Peridotite Nodules in Basalt (Xenolith)

Ultramafic Xenolith (Olivine-rich Peridotite in Basalt)

Schist with Quartz Vein

Mica Schist with Crystalline Quartz (SiO2)

Epidote

Epidote (Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH))

Quartz Vein in Host Rock

Silicon Dioxide (SiO2) within Metasedimentary or Igneous Matrix

Quartz Vein in Host Rock

Silicon Dioxide (SiO2) within Sedimentary or Igneous Matrix

Possible fossilized bone fragment

Indeterminate mineralized bone; taxon and age cannot be determined from the photo

Phyllite with Quartz Vein

Metamorphic Phyllite

Greenschist

Greenschist (Chlorite-actinolite schist)