Sedimentary (Biogenic)

Sandstone (Tumbled / Rounded)

Sedimentary Rock (Quartz arenite)

Limestone

Calcareous sedimentary rock (CaCO3)

Jasper with Hematite Inclusions

Silicon Dioxide (SiO2) with Ferric Oxide (Fe2O3)

Limonite (Ironstone Concretion)

Hydrated iron(III) oxide-hydroxide (FeO(OH)·nH2O)

Polished black stone, likely hematite or black jasper

Hematite (Fe₂O₃) or opaque chalcedony/jasper (SiO₂); image-only identification is uncertain

Likely weathered sandstone fragment

Sandstone, composed mainly of quartz (SiO₂) and feldspar grains in a clay, silica, or iron-oxide cement

Tumbled brown stone, possibly jasper or weathered chert

Uncertain; likely microcrystalline quartz (SiO₂), potentially iron-stained jasper/chert

Weathered sandstone

Quartz-rich sandstone, locally iron-oxide stained (SiO₂-dominant)

Chert / Quartz Pebble

Silicon Dioxide (SiO2)

Sandstone Pebble

Quartzose Sandstone (Sedimentary Rock)

Sandstone Pebble

Sedimentary Rock (Quartzose Sandstone)

Likely milky quartz

Quartz (silicon dioxide, SiO₂)

Weathered sandstone pebble

Quartz-rich sandstone; predominantly SiO₂ grains cemented by silica, calcite, or iron oxides

Likely bituminous coal

Coal, predominantly carbon-rich organic matter; exact rank cannot be confirmed from the image

Banded sandstone

Quartz-rich sandstone (quartz arenite or feldspathic sandstone; exact type cannot be determined from the image)

Sandstone or Siltstone

Arenite or Siltstone

Fossilized Fish Skeleton in Matrix

Vertebrata (Class: Actinopterygii), typically found in limestone or shale matrices

Jasper

Silicon dioxide (SiO2)

Quartz

Silicon dioxide (SiO2)

Quartzite Conglomerate

Conglomerate (SiO2 rich)

Banded Iron Formation

Banded Iron Formation (BIF)

Glauconitic Sandstone

Glauconitic sandstone ((K,Na)(Fe,Al,Mg)2(Si,Al)4O10(OH)2)

Quartz pebble

Silicon dioxide (SiO2)

Clear Quartz

SiO2 (Silicon Dioxide)

Pink Quartz

Silicon Dioxide (Quartz), SiO2

Mica

Mica group (often Muscovite or Biotite)

Polished Stone Pendant (Identity Unclear)

Unknown (Possibly Jasper/Agate/Quartz mixture)

Rose Quartz

Silicon Dioxide (SiO2) with trace amounts of titanium, iron, or manganese

Clear Quartz

Silicon Dioxide (SiO2)

Milky quartz

Quartz (silicon dioxide, SiO₂)

Banded gneiss

Gneiss, chiefly quartz–feldspar–mica

Worn River Pebble with Fossil Indentation

Sedimentary Rock with Fossil Infill

Sandstone (likely Graywacke or Lithic Arenite)

Clastic sedimentary rock predominantly composed of silicate grains

Rounded fossil fragment, possibly fossiliferous limestone

Unidentified carbonate fossil or fossil-bearing limestone; exact fossil cannot be determined from the photograph

Polished hematite

Hematite (Fe₂O₃), likely a tumbled specimen

Pyrite Cubes in Matrix

Iron Disulfide (FeS2) in Host Matrix

Quartz Geode Fragment

Crystalline Silicon Dioxide (SiO2)

Orange Calcite

Calcium Carbonate (CaCO3)

Satin Spar Selenite

Gypsum (Calcium Sulfate Dihydrate) - CaSO4·2H2O

Polished red jasper (likely hematite-bearing jasper)

Jasper, microcrystalline quartz (SiO₂), colored chiefly by iron oxides such as hematite/goethite

Jasper Pebble

Microcrystalline Quartz (SiO2)

Orange Calcite

Calcium Carbonate (CaCO3)