Metamorphic (Man Made)

Serpentine-rich ultramafic rock

Serpentinite (predominantly serpentine-group minerals: lizardite, chrysotile, and/or antigorite)

Lapis Lazuli

Lapis Lazuli (a rock composed primarily of Lazurite (Na,Ca)₈[(S,Cl,SO₄,OH)₂|(Al₆Si₆O₂₄)], with varying amounts of Calcite, Pyrite, and Sodalite.)

Serpentinite pebble

Serpentinite, composed chiefly of serpentine-group minerals (lizardite, chrysotile, antigorite), with possible magnetite and chlorite

Quartzite pebble

Quartzite (SiO2)

Chert / Flint

Chert (varieties include Flint)

Sedimentary

Obsidian

Obsidian (volcanic glass)

Igneous

River Rock (Granitic Gneiss)

Foliated Granitic Gneiss

Serpentine

Serpentinite (a rock composed primarily of serpentine minerals like antigorite, chrysotile, and lizardite; general formula (Mg, Fe)3Si2O5(OH)4)

Metamorphic or Sedimentary (with staining)

Pink Stained Rock (Likely Quartzite or Sandstone with Iron Oxide Staining)

Quartzite (metamorphic) or Sandstone (sedimentary); coloration likely due to hematite or other iron oxides.

Massive Quartz with Host Rock

Silicon Dioxide (SiO2)

Zoisite with Ruby (Anyolite)

Anyolite (Ca2Al3(SiO4)3(OH) + (Hb, Al, Cr)2O3)

Probable serpentinite (serpentine-rich rock)

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

Quartzite

Quartzite (primarily SiO2)

Gneiss pebble

Banded gneiss, commonly quartz–feldspar–biotite gneiss

Quartz

Silicon Dioxide (SiO2)

Soapstone

Steatite (composed primarily of Talc: Mg3Si4O10(OH)2)

Tumbled blue-green stone, likely chrysocolla or dyed chalcedony

Probable chrysocolla (hydrated copper aluminosilicate; variable composition), though appearance could also represent dyed chalcedony

Rough Emerald

Beryl (Be3Al2Si6O18 with Chromium/Vanadium impurities)

White calcite (likely tumbled calcite or marble fragment)

Calcite, calcium carbonate (CaCO₃); if the specimen is granular and rock-like, it may be marble, a calcite-rich metamorphic rock

Yellow Quartzite River Cobble

Meta-quartzite (SiO2 with iron oxide staining)

Fluorite-Gedrite in Quartz (Schist)

Fluorite (CaF2) with Gedrite in Quartz/Feldspar Matrix

Granitic Gneiss

Gneiss (Polymetamorphic Granitic Gneiss)

Tumbled green aventurine (probable)

Quartzite dominated by quartz (SiO₂), with green mica/fuchsite or chlorite inclusions

Gneiss

Gneiss (High-grade metamorphic rock)

Quartz

Quartz (SiO₂ - Silicon Dioxide)

Quartz

Quartz (SiO2 - Silicon Dioxide)

Quartz

Quartz (SiO2 - Silicon Dioxide)

Milky Quartz

Quartz (SiO2)

Anthracite Coal

Anthracite (Carbon C)

Serpentinite

Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)2-3(Si, Al, Fe)2O5(OH)4

Fossiliferous Limestone

Limestone (composed primarily of calcite with included fossils CaCO3)

Sedimentary

Hypersthene (or Enstatite/Ferrosilite)

Orthopyroxene series (Mg,Fe)SiO3 - specifically, historically hypersthene (intermediate member) now referred to as Enstatite (Mg-rich) or Ferrosilite (Fe-rich)

Banded Gneiss

Gneiss (Metamorphic high-grade rock)

Clear Quartz (Rock Crystal)

Quartz (SiO₂)

Rhodonite

Rhodonite (MnSiO3)

Quartz

Quartz (SiO₂)

Banded Gneiss

Gneiss (High-grade Regional Metamorphic Rock)

Likely graphite-rich schist

Graphitic schist; chiefly graphite and quartz/mica