Rock (Likely Sedimentary)

Porphyritic volcanic rock (likely andesite or basaltic andesite)

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

Weathered, iron-stained rock fragment

Unidentified iron-oxide-stained silicate rock; precise identification is not possible from the image

Rounded tan pebble

Unidentified fine-grained rock; the image does not show enough detail for a reliable species-level identification.

Weathered gneissic or granitic rock

Quartz–feldspar–biotite gneiss (tentative; possibly weathered granite)

Quartz with iron staining

Silicon dioxide (SiO2)

Unidentified yellow-orange mineral fragment

Possibly iron-stained quartz, calcite, or citrine; identification is uncertain from the image

Chert or silicified limestone (uncertain)

Microcrystalline quartz (SiO₂), possibly calcitic limestone (CaCO₃)

Chert (with Epidote/Quartz veining)

Cryptocrystalline silica (SiO2) with Epidote/Quartz inclusions

Agate

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Sandstone (Quartzose)

Sandstone (clastic sedimentary rock, primarily SiO2)

Sandstone (likely Graywacke or Lithic Sandstone)

Clastic Sedimentary Rock

River Rock (likely Siltstone or fine-grained Sandstone)

Clastic Sedimentary Rock

Chert / Jasper

Silicon Dioxide (SiO2)

Gneiss

High-grade metamorphic rock (Gneiss)

Quartz-rich rock, likely milky quartz vein material

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

Rounded river pebble (likely fine-grained sandstone or quartzite)

Indeterminate from image; likely quartz-rich sandstone, possibly quartzite

Rounded brown river cobble

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

Ironstone concretion (likely limonite/goethite-rich)

Iron-oxide-cemented sediment, commonly goethite (FeO(OH)) and/or limonite

Sandstone (likely Arkosic)

Clastic Sedimentary Rock (Sandstone)

Sandstone (Greywacke)

Arenite / Clastic Sedimentary Rock

Sandstone (Greywacke/Siltstone variant)

Arenite / Wacke (SiO2 with diverse mineral inclusions)

Chalcedony Geode Fragment

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Sandstone (Siltstone or Fine-grained)

Clastic sedimentary rock (primarily SiO2)

Sandstone

Sandstone (clastic sedimentary rock)

Sandstone (Fossiliferous)

Arenite / Clastic Sedimentary Rock

Quartz geode/vug specimen

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

Rounded gray sandstone or siltstone cobble

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

Quartz Geode (likely within Limestone or Dolomite matrix)

Quartz (SiO₂)

Granite (likely weathered granitic rock)

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

Unidentified dark gray rock fragment

Likely fine-grained basalt or andesite; exact identification requires testing

Fossilized Shark Tooth in Matrix

Otodus sp. (likely Otodus obliquus)

Greenstone, likely altered basalt

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

Weathered conglomeratic rock, likely iron-stained sandstone

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

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

Chert (Field Stone/Pebble)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Rounded river pebble

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

Brecciated stone pebble

Breccia

Chalcedony (Agate/Carnelian variant)

Silicon Dioxide (SiO2)

Ammonite Fossil (Iridiscent)

Ammonoidea (subclass)

Fossilized stromatolite or laminated microbial mat

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