Glass

Chert (Flint)

Microcrystalline Quartz (SiO2)

Iron-stained Quartz

Silicon Dioxide with Iron Oxide (SiO2 with Limonite/Hematite impurities)

Quartz with Iron Staining

Silicon Dioxide (SiO2) with Hematite inclusions

Libyan Desert Glass

Impactite silica glass (SiO2)

Blue Slag Glass

Ferro-silicate glass (Slag)

Pumice or Tufa/Travertine

Pumice (if igneous) or Calcareous Tufa (if sedimentary)

Quartz Mineral Specimens

Quartz (Silicon Dioxide, SiO2)

Polished white chalcedony or quartz pendant

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

Rose Quartz

Silicon Dioxide (SiO2)

Flint or chert

Microcrystalline quartz (SiO₂), likely gray chert/flint

Flint or chert

Microcrystalline quartz (SiO₂), commonly with chalcedony and minor impurities

White quartz pebble (probable)

Quartz, silicon dioxide (SiO₂)

Weathered quartz-rich rock, possibly milky quartz/quartzite

Quartz (SiO₂), likely in a quartzite or silicified host rock

Weathered brown stone, likely chert or iron-stained quartzite

Microcrystalline quartz (SiO₂), probable chert; identification is limited by the image

Tumbled blue-gray stone, likely quartzite or chalcedony

Quartz-rich rock; predominantly microcrystalline or granular SiO₂, identification uncertain from image

Tumbled yellow-orange quartzite or jasper

Quartzite, chiefly microcrystalline quartz (SiO₂), possibly iron-oxide-stained jasper

Tumbled purple chalcedony or amethyst

Microcrystalline quartz (SiO₂), possibly amethyst variety

Tumbled aquamarine-like beryl

Beryl, Be₃Al₂Si₆O₁₈ (likely pale blue-green variety)

Quartz (Iron-stained River Pebble)

Silicon Dioxide (SiO2)

Quartz Pebble with Host Rock / Schist Matrix

Silicon Dioxide (SiO2) with Metamorphic Host Rock

Quartz with Iron Oxide Inclusions

Silicon Dioxide (SiO2)

Milky Quartz / Quartz Geode Fragment

Silicon Dioxide (SiO2)

Tumbled yellow chalcedony (likely citrine or yellow jasper)

Microcrystalline quartz, SiO₂; exact identification is uncertain from the photograph

Tumbled cream chalcedony or quartz

Microcrystalline quartz, SiO₂; possibly iron-stained chalcedony

Flint or chert

Microcrystalline quartz (SiO₂), commonly with chalcedony

Chert

Microcrystalline Quartz (SiO2)

Chert (Nodule)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Flint)

Microcrystalline Silica (SiO2)

Agate (Plume/Moss variety)

Cryptocrystalline Quartz (SiO2) with iron/manganese inclusions

Chert (variations include Flint/Novaculite)

Chert (formula: SiO2)

Tumbled blue-gray stone, possibly chalcedony or quartzite

Likely microcrystalline quartz (SiO₂), but the image is insufficient for confident identification

Milky Quartz Pebble

Silicon Dioxide (SiO2)

Tumbled blue chalcedony (likely blue quartz/chalcedony)

Cryptocrystalline silica, SiO₂; likely chalcedony, possibly dyed or surface-coated

Green glassy mineral specimen, likely rough emerald or green fluorite

Tentatively beryl (Be₃Al₂Si₆O₁₈), emerald variety; synthetic/man-made glass cannot be excluded from the photograph

Clear Quartz

Silicon Dioxide (SiO2) / Rock Crystal

Polished amber-colored quartz (likely citrine or iron-stained quartz)

Quartz, SiO₂; yellow color from trace iron and/or inclusions

Polished black obsidian

Volcanic glass; predominantly rhyolitic glass, approximately 70–80% SiO₂

Quartz (Smoky or Impure Variety)

Silicon Dioxide (SiO2)

Milky quartz with iron-oxide staining

Quartz, silicon dioxide (SiO₂), likely massive or coarsely crystalline; brown areas are limonite/goethite staining

Small white rounded mineral grain, likely quartz

Quartz (SiO₂), probable milky or vein quartz

Quartz (Milky or Cloudy Quartz)

Quartz (Silicon Dioxide, SiO2)

Pink quartz-rich rock, likely rose quartz

Quartz (silicon dioxide, SiO₂), probably massive rose quartz