Rock (Likely Sedimentary)

Gneiss

High-grade metamorphic rock (Gneiss)

Porphyritic volcanic rock (likely andesite or basaltic andesite)

Porphyritic andesite/basaltic andesite; mainly plagioclase, pyroxene, and possibly olivine in a fine volcanic groundmass

Fossilized Shark Tooth in Matrix

Otodus sp. (likely Otodus obliquus)

Quartz-rich rock, likely milky quartz vein material

Mostly quartz (SiO₂); exact rock type cannot be determined from the image alone

Greenstone, likely altered basalt

Metabasalt (chlorite–actinolite–epidote assemblage), likely greenschist-facies greenstone

Quartz Geode (likely within Limestone or Dolomite matrix)

Quartz (SiO₂)

Chert / Jasper

Silicon Dioxide (SiO2)

Chert (with Epidote/Quartz veining)

Cryptocrystalline silica (SiO2) with Epidote/Quartz inclusions

Rounded brown river cobble

Likely iron-stained quartz-rich sandstone or weathered conglomeratic rock; exact identification requires testing

Sandstone (Greywacke/Siltstone variant)

Arenite / Wacke (SiO2 with diverse mineral inclusions)

Sandstone (likely with Borings or Vesicular Basalt)

Clastic Sedimentary Rock (Sandstone)

Tumbled banded gneiss

Gneiss, a foliated metamorphic rock; exact mineral composition cannot be determined from the image

Unidentified Dark Mineral or Rock

Indeterminate (Likely Silicon Dioxide or Carbon-based)

Geode or Concretion

Silica-filled nodule (likely SiO2)

Small rounded pebble (specific rock type indeterminate)

Unidentified lithic pebble; composition cannot be determined from the image

Weathered quartz pebble (tentative)

Quartz, SiO₂; possibly iron-stained quartz or quartz-rich rock

Small rounded pebble

Unidentified lithic clast; composition cannot be determined from the image

Quartz geode/vug specimen

Quartz (SiO₂), likely in a weathered iron-oxide-rich host rock

Fossil brachiopod shell

Brachiopoda; likely a ribbed Paleozoic brachiopod, exact genus uncertain from the image

Rounded beach or river pebble

Unidentified fine-grained rock; composition cannot be determined from the image

Small brown pebble (likely iron-stained quartz or chert)

Undetermined silicate pebble; possible quartz (SiO₂) or chert (microcrystalline SiO₂)

Rounded river pebble

Unidentified lithic pebble; exact rock type cannot be determined from the image

Brecciated stone pebble

Breccia

Granite (likely weathered granitic rock)

Granite; chiefly quartz (SiO₂), feldspar, and mica

Rounded gray sandstone or siltstone cobble

Lithified quartz–feldspar–clay sediment; exact petrographic identification requires testing

Sandstone

Quartz-rich clastic sandstone; exact variety cannot be determined from the image

Small weathered rock fragment

Indeterminate; possibly limestone or altered volcanic rock

Quartz-veined metamorphic rock, likely schist or phyllite

Quartz-bearing mica schist/phyllite; exact identification requires closer examination

Weathered conglomeratic rock, likely iron-stained sandstone

Probable ferruginous, clast-bearing sandstone; exact identification requires examination of a fresh surface

Sandstone (Siltstone or Fine-grained)

Clastic sedimentary rock (primarily SiO2)

Weathered fossil-bearing pebble, possibly fossiliferous limestone

Fossiliferous carbonate rock; exact fossil and rock identification are not certain from the photograph

Small rounded pebble, likely limestone or quartz-rich sedimentary fragment

Indeterminate lithic clast; probable micritic limestone (CaCO₃) or weathered quartz-rich stone

Small tan rock fragment

Indeterminate; possibly quartz-rich sandstone or iron-stained quartz

Weathered quartz-rich rock fragment

Likely quartz-bearing sandstone or granitic rock; exact identification is uncertain from the image

Fossilized Sea Urchin (Echinoid)

Echinoidea (Class) - likely replaced by Calcite or Quartz

Fossilized stromatolite or laminated microbial mat

Layered carbonate/chert fossil; exact taxon indeterminate from the image

Biotite (Black Mica)

Biotite - K(Mg,Fe)3AlSi3O10(F,OH)2

Pebble (Likely Basalt or Siltstone)

Clastic sedimentary rock or mafic volcanic rock

Weathered dark shale or slate-like rock

Fine-grained argillaceous rock; exact identification requires examination of a fresh surface

Chert (Field Stone/Pebble)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Gray sedimentary rock, likely limestone

Likely calcite-rich limestone (primarily CaCO₃); exact identification is uncertain from the photograph.

Weathered quartz-rich rock, possibly quartzite

Quartzite (tentative identification; exact rock type cannot be confirmed from the image)