Mineraloid (Human Made Geological Specimen)

Red Painted Rock

Artificial Coated Lithic Fragment

Opal cabochon or opal-like decorative specimen

Hydrated amorphous silica, SiO₂·nH₂O; likely synthetic or assembled opal material

Iron-rich sandstone or weathered ironstone

Ferruginous sandstone; primarily quartz (SiO₂) cemented or stained by iron oxides, chiefly hematite (Fe₂O₃) and goethite (FeO(OH))

Likely iron-rich slag or weathered ironstone

Hematite–goethite-rich material (Fe₂O₃/FeO(OH)); possibly industrial iron slag

Crackle Agate / Dyed Quartz

SiO2 (Silicon Dioxide)

Chert (Jasper variety)

Microcrystalline Quartz (SiO2)

White quartz-rich stone, possibly milky quartz or quartzite

Quartz (SiO₂), possibly microcrystalline quartzite

Tumbled pink-and-white quartz

Quartz, SiO₂; likely rose quartz with milky quartz

Clear quartz crystal

Quartz (silicon dioxide, SiO₂)

Pyrite in Matrix

Iron Sulfide (FeS2)

Likely tumbled jasper or iron-rich chert

Microcrystalline quartz (SiO₂), potentially hematite/goethite-bearing

Obsidian

Amorphous volcanic glass (primarily SiO2)

Painted Rock / Geode Specimen

Silicon Dioxide with artificial pigment coating

Amber

Succinite (a specific common type) or Fossilized Tree Resin (C10H16O)

Chert (Common Variety, Jasper)

Microcrystalline Quartz (SiO2)

Iron-rich vesicular rock, possibly slag or weathered basalt

Identification uncertain; likely ferruginous basalt/ironstone, with possible anthropogenic iron slag

Opalite

Synthetic Glass / Man-made Opal Simulant

Chert (Flinty variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Blue Apatite

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

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Obsidian (likely black obsidian)

Volcanic glass; predominantly rhyolitic silica glass (SiO₂-rich)

Chert Concretion (with typical hematite/limonite staining)

Sedimentary Concretion (SiO2 with FeO(OH)⋅nH2O)

Jasper

Silicon Dioxide (SiO2) with iron oxide impurities

Tumbled quartz (likely milky/rose quartz)

Quartz, silicon dioxide (SiO₂)

Iridescent bismuth crystal

Bismuth (Bi), commonly laboratory-grown and oxidized

Tumbled brown quartz crystal (likely smoky quartz or iron-stained quartz)

Quartz, silicon dioxide (SiO₂)

Obsidian

Obsidian (Volcanic Glass)

Green obsidian (likely molded or heat-treated glass-like specimen)

Volcanic glass; predominantly rhyolitic composition (silica-rich amorphous SiO₂)

Chert Pebble/Nodule

Chert (a microcrystalline or cryptocrystalline sedimentary form of quartz, SiO2)

Polished honey calcite point

Calcite (calcium carbonate, CaCO₃), likely honey/yellow calcite

Tumbled jasper (likely ocean or picture jasper)

Microcrystalline quartz/chalcedony (SiO₂) with iron-oxide and other mineral impurities

Flint or chert projectile point

Microcrystalline quartz (SiO₂), likely chalcedony-rich chert

Tumbled jasper, likely picture or brecciated jasper

Microcrystalline quartz (SiO₂) with iron-oxide and other mineral impurities

Fossiliferous Limestone (Coquina)

Biogenic Limestone (Calcium Carbonate, CaCO3)

Chert / Flint

Silicon Dioxide (SiO₂)

Banded Chert / Chalcedony

Silicon Dioxide (SiO2)

Obsidian

Obsidian (Volcanic Glass, SiO2 + impurities)

Obsidian

Obsidian (Volcanic Glass; SiO2 content > 70%)

Iron-stained chert or silicified ironstone

Microcrystalline quartz (SiO₂), likely limonite/goethite-bearing chert

Polished gray pebble

Likely quartz-rich chert or fine-grained quartzite; exact identification is uncertain from the photograph

Snowflake Obsidian

Volcanic Glass with Spherulite Inclusions (primarily SiO2)

Painted or coated beach pebble

Uncertain; likely quartz-rich sandstone, quartzite, or a rounded silicate pebble with turquoise-colored surface coating