Rock (Likely Sedimentary)

Brecciated jasper/chalcedony (iron-stained silica)

Microcrystalline quartz, SiO₂, with iron-oxide inclusions

Sandstone (likely Quartzose Sandstone)

Arenite (primarily SiO2)

Mixed river-worn rock and mineral collection

Mostly quartz/quartzite, feldspar-bearing granitoid, chert, and mafic volcanic rocks; exact species vary by pebble

River Pebbles (Basalt and Graywacke/Limestone)

Mafic Volcanic Rock / Impure Sandstone

Polished striped jasper pebble

Jasper, microcrystalline quartz (SiO₂) with iron-oxide and clay inclusions

Jasper

Silicon dioxide / Chalcedony (SiO2)

Banded Gneiss

Gneiss (High-grade regional metamorphic rock)

Sandstone (Quartzose Sandstone)

Clastic sedimentary rock (SiO2 primary composition)

Unidentified tan rock fragment

Likely limestone or calcareous sandstone; exact identification requires testing

Flagstone paving (likely sandstone or limestone)

Clastic sandstone or carbonate limestone; exact identification requires testing

Quartz (Crystalline Cluster)

Silicon Dioxide (SiO2)

Likely quartz-rich rock fragment

Probably microcrystalline quartz (SiO₂), possibly a pale chert or quartzite fragment

Agate (Carnelian-Blue Agate mix)

Silicon Dioxide (SiO2)

Weathered quartz-bearing rock, possibly sandstone or quartzite

Provisional: quartzite (mostly SiO₂); could alternatively be iron-stained quartz sandstone

Jasper (likely Iron-stained)

Silicon Dioxide (SiO2) with iron oxide inclusions

Chert (Brown variety)

Silicon Dioxide (SiO2)

Druzy Quartz Geode Fragment

Silicon Dioxide (SiO2)

Riverstone (likely Graywacke or Siltstone)

Sedimentary sandstone (Graywacke), SiO2 dominant

Chert

Microcrystalline Quartz (SiO2)

Agate (specifically Carnelian Agate or Lake Superior style Agate)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Gneiss with Orthoclase Feldspar

Gneissic Metamorphic Rock with K-Feldspar inclusions

Quartz-rich metamorphic fragment (likely mica schist)

Mica schist, probably muscovite–quartz schist

Chert (specifically Green Chert/Jasper)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Gneiss (with Mica and Quartz)

Gneissic Metamorphic Rock

Geode with Quartz and possibly Jasper/Hematite

Quartz (SiO2) and Chalcedony (cryptocrystalline SiO2), possibly stained by iron oxides

Sandstone (likely Quartzose Sandstone with mineral staining)

Arenite (composed mainly of SiO2)

Fossiliferous Brachiopod in Shale

Brachiopoda (Phylum) preserved in Carbonaceous Shale

Weathered iron-rich sandstone or laterite fragment

Ferruginous sandstone, chiefly quartz (SiO₂) cemented or stained by iron oxides/hydroxides

Weathered river pebble, likely quartz-rich sandstone or iron-stained quartzite

Provisional identification: quartz-rich sandstone/quartzite; exact composition cannot be confirmed from the image

Crushed Limestone

Calcium Carbonate (CaCO3)

Small pale rock fragment

Indeterminate; possibly quartz, calcite, or a weathered feldspar-rich fragment

Druzy Quartz on Host Rock

Silicon Dioxide (SiO2) with various iron-oxide inclusions

Fine-grained gray sandstone or quartz-rich sedimentary pebble

Likely quartz arenite or lithic sandstone; exact identification requires microscopy or testing

Light-colored weathered stone, possibly limestone or quartz-rich rock

Indeterminate; likely calcitic limestone (mostly CaCO₃) or quartz sandstone (SiO₂)

Fossiliferous Limestone (Chertified Limestone)

Calcium Carbonate (CaCO3) often replaced by Microcrystalline Silica (SiO2)

Chert (Field Stone)

Microcrystalline / Cryptocrystalline Quartz (SiO2)

Rounded iron-rich pebble

Likely hematite/goethite-bearing quartzite or ironstone; exact identification requires testing

Chert / Flint Conglomerate

Silicified Sedimentary Breccia (primarily SiO2)

Granitic Pebble (Glacial Erratic)

Granite

Glacial granite/granitoid boulder

Granite to granodiorite; chiefly quartz, feldspar, and biotite/hornblende

Ironstone Pebble

Ferruginous sedimentary rock (Fe2O3 / FeO(OH) mixed with SiO2)

Decorative polished pebbles

Likely mixed quartz-rich lithologies, including quartzite, jasper, and/or basalt