Man Made Material

Quartz (River Pebble)

Silicon Dioxide (SiO2)

Orange Calcite

Calcium Carbonate (CaCO3)

Chert (specifically Red Chert or Jasper)

Microcrystalline Quartz (SiO2)

Serpentinite (likely brecciated serpentinite)

Serpentinite; primarily serpentine-group minerals (antigorite, lizardite, chrysotile), commonly with magnetite, brucite, and relict olivine/pyroxene

Obsidian

Volcanic Glass (predominantly SiO2, approximately 70% or more)

Orthoclase Feldspar

Potassium aluminum silicate (KAlSi3O8)

Petrified Wood

Silicified Wood (primarily SiO₂)

Sandstone

Arenite (composed primarily of SiO2)

Serpentine-rich pebble

Serpentinite; chiefly serpentine-group minerals (chrysotile, lizardite, antigorite), commonly with magnetite and minor olivine/pyroxene

Chert (and its variety Flint)

Silicon Dioxide (SiO2) - Microcrystalline or cryptocrystalline Quartz

Tumbled pink feldspar (likely orthoclase or microcline)

Potassium feldspar, KAlSi₃O₈

Nephrite Jade

Ca2(Mg, Fe)5Si8O22(OH)2 (Calcium magnesium iron silicate hydroxide)

Nephrite Jade

Ca2(Mg,Fe)5Si8O22(OH)2

Serpentinized ultramafic rock (likely serpentinite)

Serpentinite; chiefly serpentine-group minerals, Mg₃Si₂O₅(OH)₄, with possible magnetite, olivine, pyroxene, and sulfides

Quartzite

Quartzite (SiO2)

Petrified Wood

Silicified Wood (primarily Quartz/Chalcedony, SiO2)

Petrified Wood

Silicified Wood (primarily Quartz/Chalcedony, formula SiO2)

Chalcedony (Agate/Carnelian variant)

Silicon Dioxide (SiO2)

Chert (Flint variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Serpentine (serpentinite)

Serpentine-group minerals, chiefly antigorite, lizardite, and chrysotile: Mg₃Si₂O₅(OH)₄

Quartzite Arrowhead (Archaeological Lithic)

Recrystallized Quartz (SiO2)

Quartz

Quartz (Silicon Dioxide, SiO2)

Chalcedony (specifically Agate or Common Opal variety)

Cryptocrystalline Silica (SiO2)

Leopard Skin Jasper

Silicon Dioxide (SiO2) with mineral inclusions

Blue Quartzite (Aventurine variety)

Silicon Dioxide (SiO2) with inclusions of Dumortierite or Magnesio-riebeckite

Quartz-rich pegmatite or quartz vein rock

Mostly quartz (SiO₂), with probable feldspar and iron-oxide staining

Polished copper-bearing rock, likely cuprite-rich copper ore

Cuprite (Cu₂O) with native copper and iron-oxide matrix, probable

Raw greenish-blue quartz-bearing mineral specimen

Likely fluorite or chalcedony/quartz; exact identification requires hardness and crystal tests

Dark mafic rock, likely basalt

Basalt (fine-grained assemblage chiefly plagioclase and pyroxene, commonly with olivine and iron oxides)

Dark igneous rock, likely basalt

Basalt; chiefly plagioclase feldspar, pyroxene, and possibly olivine

Pink Granite (River Pebble)

Felsic intrusive igneous rock (consisting of Quartz, Orthoclase Feldspar, and Plagioclase)

Granite

Granite (Felsic Plutonic Rock)

Granite

Granitoid

Sandstone

Arenite (typically composed of SiO2)

Tumbled pale greenish stone, likely serpentine or altered limestone

Probable serpentine-group rock (antigorite/lizardite), possibly serpentinite; identification is visual only

Chert (Jasper/Chalcedony)

Microcrystalline Quartz (SiO2)

Petrified Wood

Silicified wood (Quartz, SiO2)

Honey calcite (orange calcite)

Calcite, calcium carbonate (CaCO₃)

Milky Quartz with Mineral Inclusions

Silicon Dioxide (SiO2)

Cherry Creek Jasper (also known as Red Creek Jasper or Cherry Creek Agate)

Jasper, microcrystalline quartz (SiO₂)

Chert (variations include Flint/Jasper)

Cryptocrystalline Silicon Dioxide (SiO2)

Weathered banded sandstone pebble

Quartz-rich sandstone (predominantly SiO₂)