Glass

Chert (Flint)

Microcrystalline quartz (SiO2)

Chalcedony

Cryptocrystalline Quartz (SiO2)

Chert (Cherty Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Rose Quartz

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

Brown Chert

Cryptocrystalline Silica (SiO2)

Chert (Jasper/Flint variety)

Microcrystalline Quartz (SiO2)

Citrine

Citrine (Silicon Dioxide, SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Polished black stone, likely black obsidian

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

Rose Quartz

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

Banded chert (likely flint or jasperoid)

Microcrystalline quartz/chalcedony, SiO₂

Greenish quartz (likely prase/chalcedony)

Quartz, SiO₂; possibly green chalcedony or chlorite-included quartz

Tumbled quartz-rich stone, possibly milky quartz or quartzite

Quartz (SiO₂), potentially quartzite if metamorphic

Clear quartz crystal (likely quartz fragment)

Quartz, silicon dioxide (SiO₂)

Sea Glass (specifically Frosted White)

Amorphous Silica (substance: Sodium-calcium silicate glass)

Tumbled milky quartz, possibly quartzite

Quartz (SiO₂); the specimen may be a quartz-rich metamorphic rock if its texture is granular

Tumbled milky chalcedony (likely common opalite-like quartz)

Chalcedony, microcrystalline SiO₂; possibly pale common opal, hydrated SiO₂·nH₂O

Rose Quartz

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

Raw Citrine Quartz

Silicon Dioxide (SiO2)

Rose Quartz

Quartz (Silicon Dioxide) - SiO2

Tumbled pink quartz (likely rose quartz)

Rose quartz, quartz (SiO₂), commonly colored by trace elements and microscopic inclusions

Quartz (Citrine or Iron-Stained)

Silicon Dioxide (SiO2)

Snowflake Obsidian

Snowflake Obsidian (Volcanic Glass)

Polished black stone, likely black obsidian

Obsidian (volcanic glass; mainly SiO₂)

Goldstone

Not a natural mineral or rock. It is an ornamental glass.

Quartz (Milky Quartz / Greenish Quartz)

SiO2 (Silicon Dioxide)

Likely tumbled red mineral or glass imitation

Indeterminate; possibilities include red jasper (microcrystalline quartz, SiO₂) or dyed chalcedony

Fulgurite

Fulgurite (Lechatelierite/Silica glass)

Tumbled milky quartz

Quartz, silicon dioxide (SiO₂)

Pink quartz (likely rose quartz)

Rose quartz; quartz, SiO₂

Amethyst geode

Quartz (SiO₂), purple variety amethyst; commonly in basalt-hosted geodes

Tumbled amethyst

Quartz, crystalline silicon dioxide (SiO₂), purple variety colored mainly by iron impurities and irradiation

Clear Quartz

Silicon Dioxide (SiO2)

Dark flint or chert nodule

Microcrystalline quartz (SiO₂), commonly called flint when dark and nodular

Milky Quartz

Silicon Dioxide (SiO2)

Yellow Quartz (Citrinated Quartz)

Silicon Dioxide (SiO2)

Pearl and Garnet Glass

Calcium Carbonate (CaCO3) for pearl; Silicon Dioxide (SiO2) for glass

Blue Quartz / Glass Gemstone Pendant

SiO2 (Silicon Dioxide) or Synthetic Glass

Pink quartz (likely rose quartz)

Quartz, silicon dioxide (SiO₂), commonly quartz var. rose quartz

Likely flint/chert fragments

Microcrystalline quartz (SiO₂), possibly fossil-bearing chert

Polished milky quartz (likely quartz worry stone or wand)

Quartz, silicon dioxide (SiO₂)