Anthropogenic (Man Made Material Processed By Nature)

Limestone with Calcite Veins

Sedimentary Calcium Carbonate (CaCO3)

Granite Pebble

Felsic Igneous Rock (Granitic composition)

Diamond (in a jewelry setting)

Cubic Carbon (C)

Thunderegg (Agate or Quartz Geode)

Silica-filled rhyolitic nodule (SiO2)

Fossilized echinoid (sea urchin), likely a flint/chalk-associated test

Echinoid fossil; likely a regular echinoid such as Echinocidaris or related taxon, composed mainly of recrystallized calcite (CaCO₃)

Corundum (Ruby variety)

Aluminium oxide (Al2O3)

Citrine

Silicon Dioxide (SiO2) with iron impurities

Baroque Pearl

Calcium Carbonate (Aragonite or Calcite) and Conchiolin

Sandstone

Sedimentary Rock (Quartz arenite/Arkose)

Sandstone

Clastic Sedimentary Rock

Sandstone (Quartzose Sandstone)

Clastic sedimentary rock (primarily SiO2)

Sandstone

Arenite (SiO2 with various cementing agents)

Flint / Chert

Microcrystalline Quartz (SiO2)

Sandstone

Sedimentary quartz arenite

Blue-green copper mineral specimen, likely chrysocolla or turquoise

Probable chrysocolla, hydrated copper phyllosilicate (Cu₂H₂Si₂O₅(OH)₄·nH₂O); turquoise, CuAl₆(PO₄)₄(OH)₈·4H₂O, is an alternative

Sandstone

Arenite (SiO2 based)

Ametrine

Silicon Dioxide (SiO2) with iron impurities

Green cabochon gemstone pendant

Indeterminate; likely dyed green turquoise, chrysoprase, or opaque beryl set with blue/clear accent stones

Lemon Quartz

Silicon Dioxide (SiO2)

Olivine in Basalt

Peridotite / Forsterite ((Mg,Fe)2SiO4)

Pearl

Calcium Carbonate (Aragonite) with Conchiolin; formula: CaCO3

Quartz Pebble

Silicon Dioxide (SiO2)

Sandstone

Arenite (primarily SiO2)

Green Calcite

Calcium Carbonate (CaCO3)

Sandstone

Sedimentary Clastic Rock

Sandstone

Arenite (SiO2 primarily)

Quartz (Smoky Quartz variant)

Silicon Dioxide (SiO2)

Turquoise

Hydrated copper aluminum phosphate, CuAl6(PO4)4(OH)8·4H2O

Turquoise in Matrix

CuAl6(PO4)4(OH)8·4H2O

Sandstone (Iron-stained)

Arenite (primarily SiO2 with Fe2O3 staining)

Tumbled blue-green stone, likely aquamarine-bearing pegmatite or blue apatite

Probable fluorapatite, Ca5(PO4)3(F,Cl,OH), though visual identification is uncertain

Polished rhyolite (likely porphyritic rhyolite)

Rhyolite, composed chiefly of quartz and alkali feldspar with minor plagioclase, biotite, and iron oxides

Tumbled carnelian/chalcedony

Cryptocrystalline quartz, SiO₂ (iron-bearing chalcedony)

Tumbled serpentine (likely)

Serpentine-group minerals, commonly lizardite or antigorite; approximate composition Mg₃Si₂O₅(OH)₄

Weathered volcanic rock, likely andesite or basalt

Fine-grained mafic to intermediate volcanic rock; probable andesite–basalt, compositionally dominated by plagioclase with pyroxene and possibly alteration minerals

Quartz geode / iron-stained quartz vein rock

Quartz (SiO₂), likely with iron oxides and minor feldspar or host-rock minerals

Polished jasper pebble

Jasper, microcrystalline quartz (SiO₂), commonly with iron-oxide impurities

Chert (Flint)

Microcrystalline Quartz (SiO2)

Chert (Flint)

Microcrystalline silica (SiO2)

Chert (River Stone)

Microcrystalline Quartz (SiO2)

Chert (Flint)

Chert (SiO2)

Sandstone Pebble

Sedimentary Clastic Rock (Quartz Arenite)