Man Made Byproduct (Non Geological)

Opalite (likely imitation opal glass)

Man-made opalescent glass; not a natural mineral (often sold as opalite)

Pink Quartz / Sea Glass

Silicon Dioxide (SiO2)

Opalite (likely man-made opalescent glass)

Opalite; not a true mineral, typically synthetic opalescent glass (silica-based)

Milky quartz (rough quartz fragment)

Quartz, silicon dioxide (SiO₂)

Tumbled opalite (likely man-made glass)

Opalite, a trade name for opalescent glass; not natural opal

Concrete Fragment

Hardened Portland cement and mineral aggregate

Opalite

Synthetic Glass (Hydrated Crystalline Silicon Dioxide simulation)

Pyrite in Quartz (Drill Core)

Silicon Dioxide (SiO2) with Iron Sulfide (FeS2) inclusions

Zinc Alloy (Silver-plated)

Zinc Alloy Casting (Zn-Al-Mg-Cu)

Asphalt Concrete

Bituminous conglomerate

Concrete with Aggregate

Composite construction material; primary matrix is Calcium Silicate Hydrate (C-S-H)

Transit Token (RTD Denver)

Nickel-plated brass or bronze alloy (Cu-Sn-Zn-Ni)

Tumbled opalite (likely man-made glass)

Opalite glass; a synthetic opalescent glass, not a natural mineral species

Concrete Fragment

Hardened Portland Cement Composite

Chert Concretion (with typical hematite/limonite staining)

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

Pyrite Concretion (Grapestone)

Iron Sulfide (FeS2) Concretion

Blue-green faceted gemstone, possibly glass or synthetic material

Not identifiable from the image; possible synthetic spinel or glass

Asphalt (Road Aggregate)

Bituminous conglomerate

Quartz (likely milky quartz or quartz glass-like fragment)

Quartz, silicon dioxide (SiO₂)

Tumbled milky quartz

Quartz, silicon dioxide (SiO₂)

Mystic Topaz (Treated Quartz or Topaz)

Aluminum silicate fluoride hydroxide [Al2SiO4(F,OH)2] with thin-film metallic coating

Sandstone Concretion

Limonitic Sandstone Concretion

Terrazzo (Man-made Composite)

Cementitious or Resin-bound Lithic Composite

Green Sea Glass

Man-made silicate glass (weathered)

Polished brown jasper (likely brecciated or orbicular jasper)

Microcrystalline quartz/chalcedony, SiO₂, with iron-oxide and other mineral inclusions

Smelter Slag

Anthropogenic Silicate Slag

Ferrochrome Slag

Industrial Glassy Slag (Fe-Cr alloy byproduct)

Milky quartz (likely quartz crystal fragment)

Quartz, silicon dioxide (SiO₂)

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

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

Concrete

Anthropogenic Conglomerate

Opalite

Synthetic Opalized Glass

Faceted clear gemstone, likely quartz or glass imitation

Most likely quartz (SiO₂); exact identification requires refractive-index and hardness tests

Polished gemstone tower assortment

Primarily quartz varieties and simulants; apparent amethyst (SiO₂), rose quartz (SiO₂), clear quartz (SiO₂), fluorite (CaF₂), sodalite, malachite, and possibly dyed or composite stones

Rock crystal quartz fragments

Quartz (silicon dioxide, SiO₂)

Pet Rock (Man-made Quartzite or Granite Cobble)

Silicon dioxide (SiO2) mixture; commonly composed of Quartz, Feldspar, and Mica

Polished white calcite sphere (identification tentative)

Calcite, CaCO₃

Polished dendritic agate or jasper

Microcrystalline quartz (SiO₂), likely chalcedony with iron/manganese dendrites

Polished black pebble, likely basalt

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

Obsidian

Volcanic Glass (70% or more SiO2)

Clear quartz crystal (likely)

Quartz, silicon dioxide (SiO₂)

Costume Jewelry with Synthetic Gemstones

Synthetic Cubic Zirconia and Glass (SiO2 / ZrO2)

Asphalt Concrete

Bituminous Concrete