Man Made Material, Not A Natural Rock Or Mineral Specimen

Granite

Granite (composed primarily of Quartz, Feldspar, and Mica)

Citrine Quartz

Silicon Dioxide (SiO2) with iron impurities

Vesicular quartz-rich rock, possibly weathered rhyolite or silicified volcanic breccia

Silica-rich volcanic rock; likely microcrystalline quartz (SiO₂) with altered feldspar and iron-oxide staining

Cubic Zirconia

Zirconium dioxide (ZrO2)

Weathered sandstone cobble

Quartz-rich sandstone, primarily SiO₂ with clay/iron-oxide cement

Sandstone (Red Sandstone / River Stone)

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

Yellow Howlite (Dyed Magnesite/Howlite)

Dyed Ca2B5SiO9(OH)5 (Howlite) or MgCO3 (Magnesite)

Green Quartzite

Metamorphic Quartzite (often colored by chromium-bearing minerals or fuchsite)

Rounded gray pebble

Indeterminate; likely a water-worn silicate or carbonate pebble

Serpentine-rich metamorphic stone

Serpentinite, chiefly serpentine-group minerals (antigorite, lizardite, or chrysotile) with possible quartz, magnesite, and magnetite

Industrial Slag

Anthropogenic Vitreous Slag

Granite Glacial Erratic

Intrusive Phaneritic Felsic Rock (Granite)

Citrine Quartz

Silicon Dioxide (SiO2) with iron impurities

Quartz (Milky or Clear variety)

Silicon Dioxide (SiO2)

Sandstone (Ferruginous/Red Sandstone)

Clastic sedimentary rock (primarily SiO2 with Fe2O3)

Jasper

Silicon dioxide (SiO2) with impurities

Citrine

Silicon Dioxide (SiO2)

Purple Agate (Dyed Chalcedony)

SiO2 (Silicon Dioxide) with organic dyes

Peacock Ore (Bornite or Iridescent Chalcopyrite)

Bornite (Cu5FeS4) or Chalcopyrite (CuFeS2) with oxidation

Granite

Phaneritic Felsic Igneous Rock

Moissanite

Silicon Carbide (SiC)

Weathered gray stone, possibly limestone or concrete-like carbonate rock

Tentatively micritic limestone (calcium carbonate, CaCO₃); exact identification is uncertain from the image

Chert (Jasper)

Silicon Dioxide (SiO2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Greywacke (River Siltstone)

Lithic Wacke (Sandstone subfamily)

Milky Quartz (Water-worn Pebble)

Silicon Dioxide (SiO2)

Chert (often called Jasper or River Rock)

Chert (SiO2)

Sandstone

Arenite (primarily SiO2)

Petrified Wood

Silicified wood (Quartz/Chalcedony replacement of organic matter)

Vesicular basalt (weathered lava rock)

Basalt; primarily plagioclase feldspar, pyroxene, and commonly olivine (mafic volcanic rock)

Silicified fossil-bearing limestone (likely chert/agate replacement)

Microcrystalline quartz (SiO₂) replacing carbonate rock; possible fossiliferous limestone

Honey-colored chalcedony (possibly yellow/orange agate or carnelian)

Chalcedony, a microcrystalline variety of quartz; SiO₂. The color may result from iron-oxide inclusions. Exact identification is uncertain from a photograph alone.

Amethyst

Amethyst (Silicon Dioxide, SiO2 + Fe4+ impurities)

Sunstone

Andesine-Labradorite Feldspar ((Ca,Na)(Al,Si)4O8)

Rose Quartz

Rose Quartz (SiO2)

Sandstone (Ferruginous)

Arenite (composed primarily of SiO2 with Fe2O3 staining)

Unakite

Unakite (epidote-bearing altered granite; mainly pink potassium feldspar, green epidote, and quartz)

Yellow Citrine Quartz

Silicon Dioxide (SiO₂)

Hag Stone

Perforated Sedimentary Rock (typically Flint, Chert, or Limestone)

Calcite

Calcium Carbonate (CaCO3)

River Cobble (Diorite or Meta-volcanic with Quartz Veining)

Diorite (with SiO2 quartz veins)

Rounded granitic gneiss or granite cobble

Granite; primarily quartz, plagioclase and potassium feldspar with biotite/hornblende