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Acrylic or Resin (Synthetic Imitation)

Polymethyl Methacrylate (PMMA) or Polyepoxide

Obsidian

Volcanic glass (SiO2 - Silicon Dioxide with impurities)

Petoskey Stone

Hexagonaria percarinata

Granitic Pegmatite

Phaneritic Granite with Potassium Feldspar (KAlSi3O8), Quartz (SiO2), and Plagioclase

Pyrite

Iron Sulfide (FeS2)

Druzy Agate (specifically Black Druzy Agate)

Silicon Dioxide (SiO2)

Serpentinite

Serpentinite (composed primarily of serpentine minerals like antigorite, chrysotile, and lizardite)

Sandstone (with Limonite staining)

Arenite (FeOx-rich)

Amethyst

Amethyst (Silicon Dioxide - SiO2 with ferric iron impurities)

Blue Apatite

Apatite (Calcium Phosphate) - Ca5(PO4)3(F,Cl,OH)

Milky Quartz Pebble

Silicon Dioxide (SiO2)

Fossilized Bone Fragment

Permineralized Skeletal Element (Likely Vertebrate)

Bauxite

Bauxite (mixture of Gibbiste Al(OH)3, Boehmite ̳-AlO(OH), and Diaspore ́-AlO(OH))

Quartzite Arrowhead (Archaeological Lithic)

Recrystallized Quartz (SiO2)

Green Quartz (Prasiolite/Adventurine/Jasper)

Silicon Dioxide (SiO2)

Bornite (Peacock Ore)

Bornite (Cu5FeS4)

Smoky Quartz Geode Slice

Silicon Dioxide (SiO2)

Granite or Granodiorite (Weathered)

Granite

Pyrite in Matrix

Iron Sulfide (FeS2)

Jasper

Jasper (Silicon Dioxide, SiO2)

Schist

Chlorite/Mica Schist

Jasper (likely a variety of Brecciated Jasper or a patterned variety)

Silicon dioxide (SiO2)

Micaceous Schist

Mica Schist (primarily Muscovite or Biotite KAl2(AlSi3O10)(OH)2)

Pumice

Pumicite (Amorphous volcanic glass)

Schorl (Black Tourmaline) in Quartz Matrix

Schorl: NaFe3Al6(BO3)3Si6O18(OH)4 (Complex Borosilicate)

Quartzite (Iron-stained)

Quartzite (SiO2)

Sandstone

Arenite (composed primarily of Quartz: SiO2)

Druzy Quartz on Limestone

Silicon Dioxide (SiO2)

Quartzite with Iron inclusions

Metamorphosed Sandstone (SiO2 with Fe2O3)

Limonite

Limonite (Hydrous iron oxides, FeO(OH)·nH2O)

Quartz Pebble

Silicon Dioxide (SiO2)

Aragonite (variety 'Flos Ferri')

Aragonite (CaCO3)

Blue Calcite

Calcium Carbonate (CaCO3)

Red Sandstone

Arenite (with Iron Oxide / Hematite cementation)

Limonite (Iron Ore)

Limonite (Iron oxide-hydroxide mixture, FeO(OH)·nH2O)

Quartzite

Quartzite (primarily SiO2)

Granite

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

Crushed Granite Gravel

Granite (Mainly Quartz, Feldspar, and Mica)

Celestite (Celestine)

Strontium sulfate (SrSO4)

Lapis Lazuli (Lazurite crystals on Marble)

Lazurite / (Na,Ca)8[(S,Cl,SO4,OH)2|(AlSiO4)6]

Banded Agate (specifically Red Agate or Sardonyx variety)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Quartzite

Quartzite (Mainly SiO2)