Glass

Quartz (Iron-stained)

Silicon Dioxide (SiO2)

Milky Quartz

Quartz (Silica - SiO2)

Rose quartz

Quartz (SiO₂), pink variety

Smoky quartz (likely faceted cabochon or rough fragment)

Quartz, silicon dioxide (SiO₂), smoky variety colored by irradiation-related defects

Amethyst quartz fragment

Quartz, SiO₂; purple coloration from iron-related defects and irradiation

Tumbled smoky quartz

Quartz (SiO₂), brown smoky variety

Rough aquamarine (likely beryl)

Beryl, Be₃Al₂Si₆O₁₈; blue color from iron impurities

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Tumbled obsidian

Volcanic glass; chiefly silica-rich rhyolitic glass (approximately 70–80% SiO₂)

Green aventurine (likely)

Quartz, SiO₂, with fuchsite or other green inclusions

Flint or chert fragment

Microcrystalline quartz (SiO₂), commonly termed chert or flint

Obsidian (black volcanic glass)

Obsidian; silica-rich volcanic glass, typically rhyolitic to dacitic composition

Blue cabochon gemstone ring

Uncertain; likely blue sapphire (corundum, Al₂O₃), blue topaz, or synthetic glass/spinel

Clear quartz pebble

Quartz (silicon dioxide, SiO₂)

Green aventurine (tumbled)

Quartz-rich aventurine; predominantly microcrystalline SiO₂ with fuchsite mica inclusions

Tumbled rose quartz

Quartz, silicon dioxide (SiO₂), pink variety

Small tumbled brown stone, likely iron-stained quartz or jasper

Quartz (SiO₂) or microcrystalline quartz (chalcedony/jasper), identification uncertain from the image

Milky quartz

Quartz (silicon dioxide, SiO₂)

Weathered quartz-rich cobble, possibly milky quartz with iron staining

Quartz (SiO₂), likely with iron-oxide/hydroxide coatings and minor host-rock inclusions

Milky quartz with dark mineral veins

Quartz, silicon dioxide (SiO₂), likely massive vein quartz; dark veins may be chlorite, mica, iron/manganese oxides, or a sulfide mineral

Iron-stained quartz (likely quartzite or vein quartz)

Quartz, SiO₂, with iron-oxide/hydroxide staining; possibly ferruginous quartzite

Iron-stained chert or flint nodule

Microcrystalline quartz (SiO₂), likely chert with limonite/goethite staining

Rounded quartz-rich cobble

Likely quartzite or siliceous sandstone; predominantly microcrystalline SiO₂ with possible feldspar and iron-oxide staining

Tumbled black obsidian (likely)

Volcanic glass; primarily rhyolitic silica glass (SiO₂-rich, amorphous)

Obsidian (likely blue-sheen or coated obsidian)

Volcanic glass; primarily rhyolitic silica glass (SiO₂-rich, noncrystalline)

Likely weathered quartzite or quartz-rich pebble

Quartzite; predominantly crystalline SiO₂

Polished black stone, likely basalt or basaltic glass

Fine-grained basalt (possibly devitrified volcanic glass); mainly plagioclase and pyroxene, with iron-titanium oxides

Quartz (Iron-stained)

Silicon Dioxide (SiO2) with Iron Oxide inclusions

Quartzite River Pebble

Quartzite (SiO2)

Rounded quartz-rich pebble

Likely quartzite or quartz-rich sandstone; predominantly SiO₂

Weathered sandstone

Quartz-rich sandstone, primarily SiO₂ with variable feldspar, mica, and clay minerals

Lodolite (Garden Quartz)

Silicon Dioxide (SiO2) with inclusions (Chlorite, Hematite, etc.)

Small white mineral fragment

Indeterminate; possibly quartz, calcite, or feldspar

Chert / Flint

Silicon dioxide (SiO2)

Iron-stained Quartz Pebble

Silicon Dioxide (SiO2) with Hematite/Limonite coatings

Rose Quartz Beads

Silicon Dioxide (SiO2) - Quartz Variety

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Black Chert (Flint / Basanite)

Microcrystalline / Cryptocrystalline Quartz (SiO2)

Chert (Flint)

Microcrystalline quartz (SiO2)

Chert

Microcrystalline quartz (SiO2)

Rose Quartz

Silicon dioxide (SiO2) with trace amounts of titanium, iron, or manganese

Chert (Jasper)

Microcrystalline Quartz (SiO2)