Mineraloid (Human Made Geological Specimen)

Obsidian

Volcanic glass (SiO2 - Silicon Dioxide with impurities)

Bismuth crystal

Bismuth (Bi), commonly laboratory-grown hopper crystal

Common opal in iron-stained host rock

Opal (hydrated amorphous silica, SiO₂·nH₂O), likely common opal

Chert (Green Chert or Jasper)

Microcrystalline Quartz (SiO2)

Botryoidal chalcedony with iron-oxide staining

Microcrystalline quartz (SiO₂), likely iron-oxide-bearing chalcedony

Tumbled chalcedony or quartz pebble

Microcrystalline quartz, SiO₂ (likely chalcedony); exact identification is uncertain from the image

Tumbled chalcedony or quartz pebble

Microcrystalline quartz (SiO₂), likely orange chalcedony/carnelian

Obsidian

Amorphous volcanic glass (SiO2)

Small clear crystal, possibly quartz or glass-like gemstone

Uncertain; likely quartz (SiO₂), but the image is insufficient to exclude man-made glass or cubic zirconia

Chert or heavily weathered flint

Microcrystalline quartz (SiO₂), likely chert/flint

Chert (Arrowhead Preform or Point)

Chert (Microcrystalline Quartz, SiO2)

White Precious Opal

Hydrated Silica (SiO2·nH2O)

Common Opal in Host Rock

Hydrated Silica (SiO2·nH2O)

Likely weathered iron-rich rock or slag fragment

Indeterminate; possibly limonite/goethite-bearing rock (FeO(OH)·nH₂O) or industrial iron slag

Amber / Copal

Succinite (fossilized resin)

Tumbled quartz-rich pebble

Microcrystalline quartz (SiO₂), possibly milky quartz or quartzite

Opalite (likely man-made glass)

Opalite; amorphous silica glass, not a natural mineral

Tumbled quartz pebble, possibly citrine or iron-stained quartz

Quartz (SiO₂), likely microcrystalline or granular quartz

Tumbled orange aventurine (likely quartzite)

Quartz-rich rock, primarily microcrystalline quartz (SiO₂)

Black Obsidian

Volcanic Glass (predominantly SiO2)

Chalcedony (Agate/Chert variety)

Silicon Dioxide (SiO2)

Tumbled milky quartz pebble

Quartz (silicon dioxide, SiO₂)

Tumbled milky quartz

Quartz (silicon dioxide, SiO₂)

Snowflake Obsidian

Volcanic Glass with Spherulite Inclusions (70-75% SiO2)

Amber / Copal

Succinite (fossilized tree resin)

Chert (Flint)

Microcrystalline quartz (SiO2)

Polished white calcite (likely satin spar variety)

Calcite, calcium carbonate (CaCO₃)

Polished orbicular gabbro (likely “leopard-skin” or larvikite-type material)

Gabbro, a coarse-grained mafic plutonic rock; chiefly plagioclase feldspar and pyroxene, with possible olivine/amphibole and iron oxides

Milky Quartz

Silicon Dioxide (SiO2)

Amber

Succinite (C10H16O)

Polished black stone, likely basalt or fine-grained mafic rock

Basalt (probable; identification uncertain from photograph)

Chert (Jasper/Flint variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Obsidian

Volcanic Glass (Amorphous Silicon Dioxide)

Quartz heart (likely milky/included quartz)

Quartz, silicon dioxide (SiO₂)

Milky quartz pebble

Quartz, silicon dioxide (SiO₂)

Tumbled milky quartz (likely quartzite or chalcedony)

Quartz, SiO₂; possibly microcrystalline chalcedony

Amber

Succinite (specific to Baltic amber), fossilized tree resin

Bumblebee Jasper

Anhydrite-Aragonite mixture with Orpiment and Realgar

Fulgurite

Luechatelierite (SiO2 glass)

Blue-gray stone pebble (possibly slag or a weathered rock)

Unidentified fine-grained rock; composition cannot be determined from the image

Chert (Jasper/Flint variety)

Microcrystalline Quartz (SiO2)

Obsidian (black volcanic glass), possibly slag or basalt

Obsidian; chiefly amorphous volcanic silica glass, approximately SiO₂-rich rhyolitic composition