Mineral (Man Made Glass)

Geode fragment, likely quartz-lined basalt or chalcedony nodule

Microcrystalline quartz (SiO₂), possibly with iron-oxide staining in a basaltic host

Translucent agate/chalcedony

Microcrystalline quartz (SiO₂), likely chalcedony with agate-like banding

Tumbled brown stone, likely smoky quartz or brown jasper

Probable smoky quartz (SiO₂) or iron-rich jasper (microcrystalline SiO₂); image alone is insufficient for certainty

Tumbled blue stone, likely blue aventurine or dyed quartzite

Quartz (SiO₂), likely with inclusions or artificial dye; exact identification requires testing

Quartz (Druzy) on Matrix

Silicon Dioxide (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Blue Cat's Eye Quartz (Heated/Dyed)

Silicon Dioxide (SiO2) with fibrous inclusions

Green Aventurine

Silicon Dioxide with Fuchsite inclusions (SiO2 + K(Al,Cr)2AlSi3O10(OH)2)

Quartz Pebble

Silicon Dioxide (SiO2) with host rock matrix

Green Aventurine

SiO2 (Silicon Dioxide with Fuchsite inclusions)

Green Aventurine

Silicon Dioxide (SiO2) with Chromium-bearing Fuchsite

Aventurine

Aventurine (Silicon Dioxide with Fuchsite inclusions) - SiO2

Green Aventurine

Aventurine Quartz (SiO2 with Fuchsite inclusions)

Quartz

Silicon Dioxide (SiO2)

Clear Quartz

Silicon Dioxide (SiO2)

Quartz-rich rock, possibly milky quartz or quartzite

Quartz (SiO₂), potentially quartzite if the grainy texture is rock-wide

Likely obsidian (possibly tektite or slag glass)

Volcanic glass; primarily SiO₂, noncrystalline

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Clear Quartz (Rock Crystal) Bracelet

Silicon Dioxide (SiO2)

Milky Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Sandstone (Ferruginous)

Arenite (primarily SiO2 with Fe2O3 staining)

Tumbled milky quartz

Quartz (silicon dioxide, SiO₂)

Tumbled banded calcite (often sold as “onyx” or green onyx)

Calcite, CaCO₃; commonly banded cave/travertine calcite

Snowflake Obsidian

Vitreous Volcanic Rock (Amorphous Silicate), SiO2

Milky Quartz with Chlorite/Amphibite Inclusions

Silicon Dioxide (SiO2) with various mineral inclusions

Quartz-rich pegmatite or quartz vein rock

Mostly quartz (SiO₂), with probable feldspar and iron-oxide staining

Clear Quartz / Rock Crystal

Silicon Dioxide (SiO2)

Quartz

Silicon Dioxide (SiO2)

White Quartz Pebble

Silicon Dioxide (SiO2)

Sandstone (Ferruginous)

Arenite with Hematite cement (SiO2 + Fe2O3)

Sandstone (Ferruginous)

Arenite (primarily SiO2 with Fe2O3 staining)

Milky Quartz

Crystalline Silicon Dioxide (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Green Aventurine

Silicon Dioxide (SiO2) with Fuchsite inclusions

Aventurine

Aventurine Quartz

Mahogany Obsidian

Volcanic Glass with Hematite inclusions (SiO2 + Fe2O3)

Green Aventurine

Silicon Dioxide (SiO2) with inclusions of Fuchsite (K(Al,Cr)2(AlSi3O10)(OH)2)

Mica in Quartz Host

Muscovite (KAl2(AlSi3O10)(OH)2) in Quartz (SiO2)

Green Aventurine

Silicon Dioxide (SiO2) with inclusions of Fuchsite mica

Green Aventurine

Silicon Dioxide (SiO2) with Fuchsite inclusions

Green Aventurine

Aventurine Quartz (SiO2 with Fuchsite inclusions)