Man Made Material

Chert (often called Flint)

Chert (Cryptocrystalline Silica, SiO2)

Tumbled green-and-white stone, likely serpentine

Serpentinite; chiefly serpentine-group minerals (antigorite, lizardite, or chrysotile), commonly with magnetite and carbonate veins

Red jasper (likely iron-rich chert)

Microcrystalline quartz (SiO₂), colored by hematite/goethite; possibly brecciated jasper

Jasper

Silicon dioxide (SiO2)

Tumbled jasper, likely red/brown jasper

Microcrystalline quartz (chalcedony), SiO₂, colored chiefly by iron oxides

Serpentinized ultramafic rock with magnesite

Serpentinite, chiefly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), with likely magnesite (MgCO₃) and minor chromite/magnetite

Banded Agate

Agate (chalcedony variety of Silicon Dioxide, SiO2)

Polished Picasso jasper

Silicified carbonate rock, commonly marketed as Picasso jasper; composition varies and is not a single mineral species

Limestone

Sedimentary Calcium Carbonate (CaCO3)

Brecciated jasper, possibly rainforest jasper

Jasper: microcrystalline to cryptocrystalline quartz, SiO₂, commonly containing hematite, goethite, chlorite, epidote, and other iron- and manganese-bearing minerals

Granite

Granite (Phaneritic Quartz-Feldspar Felsic Rock)

Polished brecciated jasper pebble

Microcrystalline quartz (SiO₂), with iron-oxide inclusions

Limestone

Calcium Carbonate (CaCO3)

Likely basalt (possibly a dark beach pebble)

Basalt; fine-grained mafic volcanic rock composed mainly of plagioclase and pyroxene, commonly with olivine

Rhodonite

Rhodonite, manganese inosilicate — MnSiO₃; the specimen may include quartz, feldspar, and black manganese-oxide minerals in the matrix

Polished greenstone (likely serpentinite)

Serpentinite, chiefly antigorite/lizardite Mg₃Si₂O₅(OH)₄, possibly with magnetite

Dyed Blue Agate Slice

Silicon Dioxide (SiO2)

Green Calcite (Onyx Marble)

Calcium Carbonate (CaCO3)

Red Sandstone

Arenite (with iron oxide cement)

Leopard Skin Jasper

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Microcrystalline Quartz (Chert/Agate)

Silicon Dioxide (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Metallic sulfide ore, likely pyrite-bearing rock

Pyrite (FeS₂), possibly with marcasite or other sulfides

Bog Iron / Limonite Concretion

Goethite/Limonite mixture (FeO(OH)·nH2O)

Chalcedony

Silicon Dioxide (SiO2)

Tumbled gray-green metamorphic rock, likely serpentinite or chlorite schist

Serpentinite/chlorite-rich ultramafic metamorphic rock; commonly dominated by antigorite, lizardite, or chlorite with minor magnetite and talc

Dalmatian jasper

Dalmatian stone, typically a leucocratic alkali-feldspar-rich porphyritic igneous rock with black arfvedsonite or aegirine inclusions

Sandstone (Red Sandstone / River Stone)

Arenite (composed primarily of Quartz, SiO2, with Iron Oxide cementation)

Red Sandstone

Arenite (SiO2 based with Fe2O3)

Picture Jasper

Silicon Dioxide (SiO2) with mineral inclusions

Quartzite Pebble

Quartzite (SiO2)

Limestone

Sedimentary Calcium Carbonate (CaCO3)

Likely petrified wood

Silicified wood, chiefly microcrystalline quartz (SiO₂)

Tumbled black-and-white stone, likely dendritic agate or jasper

Cryptocrystalline quartz (SiO₂), possibly chalcedony with manganese-oxide dendrites

Red Sandstone

Arenite (Ferruginous Sandstone)

Iron Meteorite

Iron Meteorite (primarily Kamacite and Taenite, Fe-Ni alloys)

Polished orbicular jasper (likely ocean jasper)

Silicified microcrystalline quartz/chalcedony (SiO₂), with iron-oxide and other mineral inclusions

Uncertain polymict breccia or altered volcanic rock

Likely hydrothermally altered volcanic breccia; exact mineral identification requires testing

Banded malachite cabochon

Malachite, Cu₂CO₃(OH)₂; the dark bands may be manganese-oxide or other sulfide-rich matrix, and could also indicate a composite or treated specimen

Limestone

Calcium Carbonate (CaCO3)

Basalt with Quartz/Feldspar Inclusions

Amygdaloidal or Porphyritic Mafic Volcanic Rock with Siliceous Veining

Fossiliferous Limestone

Calcium Carbonate (CaCO3) with Bioclasts