Anthropogenic (Man Made Material Processed By Nature)

Tumbled yellow calcite

Calcite (calcium carbonate, CaCO₃)

Quartzite

Metamorphic Quartzite (SiO2)

Argillite (with Barnacles)

Argillite (metamorphosed mudstone/shale)

Dyed Alum or Dyed Quartz (Ornamental Crystal)

Silicon Dioxide (SiO2) or Potassium Alum [KAl(SO4)2·12H2O]

Jasper (Mookaite style)

Jasper (Silica-rich Microcrystalline Quartz, SiO2)

Orange Quartz (Citrine Quartz variety)

Silicon Dioxide (SiO2)

Milky quartz pebble

Quartz (SiO₂), commonly called milky quartz

Likely obsidian (possibly tektite or slag glass)

Volcanic glass; primarily SiO₂, noncrystalline

Fossiliferous Limestone

Calcite-rich Fossiliferous Limestone (CaCO3)

Diamond

C (Native Carbon)

Specular Hematite (Specularite)

Iron Oxide (Fe2O3)

Fancy Jasper (Butterfly Carving)

Silicon Dioxide (SiO2) with iron and manganese inclusions

Sandstone

Arenite (SiO2 principal)

Iron meteorite fragment (likely weathered meteorite)

Fe–Ni metal, commonly kamacite with taenite; possible stony-iron or iron-oxide fusion crust

Quartz-rich rock, likely chert or chalcedony

Microcrystalline silica (SiO₂), possibly quartz/chalcedony

Greenish translucent mineral fragment

Indeterminate; possibly serpentine, epidote, or green glassy feldspar

Pink Quartz (Rose Quartz variant)

Silicon Dioxide (SiO2)

Pink Granite

Granite (Felsic Plutonic Rock)

Granite

Granite (a phaneritic intrusive igneous rock consisting mainly of quartz, alkali feldspar, and plagioclase)

Quartz (likely Milky Quartz or Chalcedony)

Quartz (SiO2 - Silicon Dioxide)

Tumbled green aventurine (probable)

Quartz, SiO₂, with green fuchsite mica inclusions

Chert (often called Flint or Jasper)

Silicon Dioxide (SiO2)

Tumbled yellow chalcedony (likely citrine or yellow jasper)

Microcrystalline quartz, SiO₂; exact identification is uncertain from the photograph

Selenite (gypsum)

Gypsum, CaSO₄·2H₂O; variety commonly called satin spar or selenite

Polished carnelian-rich agate (likely polyhedral jasper/chalcedony)

Microcrystalline quartz, SiO₂, with iron-oxide inclusions

Likely slag or metallic industrial byproduct

Unidentified iron-rich ferrous slag; possibly magnetite-bearing slag

Orange Quartzite (or Aventurine Quartz)

Quartzite (primarily SiO2 with Hematite or Goethite inclusions)

Turquoise

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

Pink chalcedony (likely rough agate/chalcedony)

Microcrystalline quartz, SiO₂; chalcedony variety, possibly iron-bearing

Weathered chert or jasper nodule

Microcrystalline quartz (SiO₂), likely chalcedony/jasper with iron-oxide staining

Polished chert or jasper cobble

Microcrystalline quartz (SiO₂), commonly called chert; iron-oxide-bearing varieties are jasper

Slate

Foliated Metamorphic Rock (primarily composed of quartz, illite, and chlorite)

Blue Dyed Agate

Chalcedony (Silicon Dioxide, SiO2)

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2)

Diamond (in a jewelry setting)

Diamond (Carbon, C)

Nephrite Jade / Greenstone

Tremolite-Actinolite solid solution series [Ca2(Mg,Fe)5Si8O22(OH)2]

Pyrite

Iron Pyrite (FeS2)

Blue Aura Quartz

Silicon Dioxide (SiO2) with metallic vapor coating

Chevron Amethyst

Silicon Dioxide (SiO2) with iron impurities

Weathered quartz-rich rock, possibly milky quartz or quartz-bearing granite

Quartz (SiO₂), potentially with feldspar and iron-oxide staining

Red jasper

Jasper (microcrystalline quartz, SiO₂), iron-oxide-rich variety

Red jasper / iron-rich chert

Microcrystalline quartz (SiO₂) colored by hematite/goethite