None

Weathered limestone

Micritic limestone, primarily calcite (CaCO₃)

Porphyritic basalt (possibly basaltic andesite)

Plagioclase-phyric basalt; mainly plagioclase feldspar and pyroxene, with minor olivine or iron oxides

Rounded basalt pebble

Basalt, a fine-grained mafic volcanic rock composed mainly of plagioclase and pyroxene, commonly with minor olivine and iron-titanium oxides

Gold

Native Gold (Au)

Weathered sandstone

Quartz-rich clastic sandstone, likely iron-oxide stained

Polished black stone, likely obsidian

Volcanic glass (approximately rhyolitic composition; mostly SiO₂)

Porphyritic basalt (likely vesicular basalt)

Basalt; fine-grained mafic volcanic rock, chiefly plagioclase feldspar and pyroxene, with possible olivine phenocrysts

Chert (specifically Flint or Common Chert)

Silicon Dioxide (SiO2)

Note: Item is not a geological specimen

n/a

Rounded quartz pebble (tentative)

Quartz, silicon dioxide (SiO₂)

Shungite

Non-crystalline carbon (Fullerene-bearing)

Citrine Quartz (Raw)

Silicon Dioxide (SiO2)

Chert (Jasper variation)

Microcrystalline Quartz (SiO2)

Chert (or Jasper)

Microcrystalline Quartz (SiO2)

Obsidian

Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)

Coal (specifically Bituminous or Anthracite)

Organic sedimentary rock; primarily Carbon (C) with varying H, S, O, N

Cullet Glass (Strawberry Glass)

Amorphous Silicon Dioxide (SiO2) with metallic dopants

Obsidian

Volcanic Glass (70-75% SiO2)

Dinosaur Fossil (Tyrannosaurus rex skull replica/specimen)

Tyrannosaurus rex (fossilized in permineralized sedimentary matrix)

Aura Quartz (Titanium-coated Quartz)

Silicon Dioxide (SiO2) with metallic vapor coating

Chert (River Pebble)

Microcrystalline Quartz (SiO2)

Agate Geode Node

Cryptocrystalline Quartz (SiO2)

Agate Geode Node

Cryptocrystalline Quartz (SiO2)

Lake Superior Agate

Chalcedony (SiO2 with iron impurities)

Moqui Marbles

Iron Oxide Concretion (Hematite/Goethite)

Chert (Arrowhead)

Chert (SiO2)

Chert (River Stone)

Microcrystalline Quartz (SiO2)

Weathered sandstone fragment

Clastic sandstone, composed mainly of quartz and feldspar grains cemented by silica, calcite, or iron oxides

Tumbled black obsidian

Volcanic glass; rhyolitic obsidian, primarily SiO₂

Dark volcanic rock, likely basalt

Basalt; primarily plagioclase feldspar, pyroxene, and often olivine

Tumbled red sandstone pebble

Quartz-rich sandstone, commonly iron-oxide-stained (SiO₂-dominant)

Weathered limestone fragment

Calcite-rich limestone (CaCO₃), possibly fossiliferous or brecciated

Weathered sandstone pebble

Quartz-rich sandstone, commonly arkose or lithic sandstone

Basalt

Mafic volcanic rock, chiefly plagioclase feldspar, pyroxene, and commonly olivine

Black polished stone, likely black obsidian

Obsidian; volcanic glass, predominantly silica-rich rhyolitic composition

Rounded basalt cobble

Basalt, a fine-grained mafic volcanic rock composed mainly of plagioclase and pyroxene, commonly with olivine and iron oxides

Obsidian

Volcanic Glass (SiO2 + impurities)

Obsidian

Obsidian (Volcanic Glass)

Corundum (Sapphire/Ruby in Matrix)

Corundum (Al2O3)

Weathered sandstone

Quartz-rich clastic sandstone, likely iron-oxide stained

Blue-green turquoise-like tumbled stone

Turquoise, hydrous copper aluminum phosphate: CuAl₆(PO₄)₄(OH)₈·4H₂O

Obsidian

Amorphous volcanic glass (SiO2)