Weathered sandstone fragment
Clastic sandstone, composed mainly of quartz and feldspar grains cemented by silica, calcite, or iron oxides
sedimentary
Category
Sedimentary (Anthropogenic)
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Small brown quartz-rich pebble, possibly chert or jasper
Microcrystalline quartz (SiO₂), tentative
mineral
River Stones (Basalt and Sedimentary Rock)
Basalt (dark specimen) and Siltstone/Mudstone (reddish specimen)
igneous and sedimentary
Limestone (or Sandstone)
Calcium Carbonate (CaCO3) / Silica (SiO2)
sedimentary
Fossil Brachiopod or Mollusk Cast
Phylum Brachiopoda / Mollusca internal mold
fossil
Sandstone
Sedimentary Clastic Rock (Quartz Arenite)
sedimentary
Fossiliferous Limestone
Biogenic Limestone (Calcium Carbonate, CaCO3)
sedimentary
Limestone Pebble
Sedimentary Calcium Carbonate (CaCO3)
sedimentary
Sandstone Pebble
Sedimentary Rock (Quartzose Sandstone)
sedimentary
Sandstone
Arenite
sedimentary
Limestone
Calcium carbonate (CaCO3)
sedimentary
Petrified Wood
Silicified Wood
fossil
Coal
Bituminous or sub-bituminous coal (carbonaceous rock)
sedimentary
Starfish Fossil
Asteroidea fossil
fossil
Jasper
Microcrystalline Quartz (SiO2)
sedimentary
Conglomerate
Conglomerate (a clastic sedimentary rock)
Sedimentary
Dendritic Siltstone
Siltstone with Manganese Dendrites (MnO2)
sedimentary
Sandstone
Sedimentary rock composed mainly of quartz sand grains
sedimentary
Chert (Jasper/Agate variety)
Microcrystalline Quartz (SiO2)
sedimentary
Fossilized Insect in Nodular Matrix
Invertebrata / Insecta fossil in sedimentary concretion
fossil
Chalk / Sedimentary Limestone
Calcium Carbonate (CaCO3) - Biogenic Sedimentary Rock
sedimentary
Chalk (Sedimentary Limestone)
Calcium Carbonate (CaCO3) - Bioclastic Limestone
sedimentary
Painted Rock
Weathered Sedimentary Rock (Painted)
sedimentary
Banded sandstone (likely quartzitic sandstone)
Quartz-rich sandstone; predominantly quartz (SiO₂) with iron-oxide cement and minor feldspar/clay
sedimentary
Conglomerate
Conglomerate Rock
sedimentary
Septarian Nodule (Septarian Dragon Stone)
Septarian Concretion (Composition: Calcite, Aragonite, and Limestone/Clay)
sedimentary
Likely weathered sandstone or iron-stained limestone pebble
Indeterminate clastic carbonate/siliciclastic rock; mineral composition likely quartz, feldspar, and/or calcite with iron oxides
sedimentary
Quartz geode (likely chalcedony-lined geode)
Silica geode: microcrystalline quartz/chalcedony with drusy quartz (SiO₂), possibly iron-oxide staining
mineral
Iron-rich chert or jasper
Microcrystalline quartz (SiO₂), stained by hematite/goethite
sedimentary
Calcite crystal cluster
Calcite (calcium carbonate, CaCO₃), likely honey or amber calcite
mineral
Possible flint (chert) fragment
Microcrystalline quartz (SiO₂), commonly called flint when dark and nodular
sedimentary
Tumbled brown quartz/chert pebble
Microcrystalline quartz (SiO₂), possibly chert or jasper
mineral
Geode (Unopened)
Siliceous Septarian Concretion / Geode (SiO2)
sedimentary
Red jasper (likely polished/tumbled)
Jasper, microcrystalline quartz (SiO₂) colored by iron oxides
mineral
Polished brecciated jasper (likely ocean jasper or brecciated agate)
Microcrystalline quartz, SiO₂, with iron-oxide inclusions and possible chalcedony
gemstone
Chert / Chalcedony Nodule
Silicon Dioxide (SiO2)
sedimentary
Quartz Geode
Silicon Dioxide (SiO2) in Geode form
mineral
River Jasper
Silicon Dioxide (SiO2) with impurities
sedimentary
Pyrite (on Shale/Matrix)
Iron Disulfide (FeS2)
mineral
Sea Glass (White/Clear)
Amorphous Silica (Alkali-Lime-Silica Glass), SiO2 + Na2O + CaO
Anthropogenic (Man-made product subject to geological processes)
Weathered iron-rich sedimentary rock (probable laterite/ironstone)
Limonite/goethite-rich ferruginous material; commonly approximated as FeO(OH)·nH₂O with clay and quartz
sedimentary
Chert (likely chalcedony-rich flint)
Microcrystalline quartz, SiO₂ (quartz/chalcedony)
sedimentary