Synthetic Or Natural Fiber

Citrine or Yellow Quartz Pebble

Silicon Dioxide (SiO2)

Orange Quartzite (or Quartz River Pebble)

Silicon Dioxide (SiO2) - Quartzite

Yellow Quartz (Citrine or Iron-Stained Quartz)

Silicon Dioxide (SiO2)

Polished jasper pebble

Microcrystalline quartz (SiO₂), commonly with iron-oxide inclusions

Quartz (Yellow / Citrine Pebble)

Silicon Dioxide (SiO2)

Yellow Quartz / Quartzite Pebble

Silicon Dioxide (SiO2)

Emerald

Beryl (variety Emerald), Be3Al2Si6O18 with Cr and/or V

Green Quartz (Prasiolite or Aventurine)

Silicon Dioxide (SiO2)

Weathered sandstone or siltstone pebble

Clastic sedimentary rock, likely quartz-rich sandstone (dominantly SiO₂)

Ruby (Corundum)

Corundum (Aluminum Oxide) with chromium trace elements, Al2O3

Quartz (Citrine / Golden Quartz)

Silicon Dioxide (SiO2)

Yellow Quartz (Citrine or Iron-stained Quartz)

Silicon Dioxide (SiO2)

Rough Quartz (var. Citrine or Yellow Quartz)

Silicon Dioxide (SiO2)

Tumbled milky quartz

Quartz (silicon dioxide, SiO₂)

Tumbled yellow quartz (likely citrine or iron-stained quartz)

Quartz, silicon dioxide (SiO₂), colored yellow by iron impurities; possibly heat-treated amethyst

Tumbled dark purple quartz, likely amethyst

Quartz (SiO₂), purple variety amethyst; possibly iron-bearing quartz with surface sparkle

Tumbled white quartz pebble

Quartz (silicon dioxide, SiO₂), possibly milky quartz

Yellow Quartz (Citrine or Iron-Stained Quartz)

Silicon Dioxide (SiO2)

Yellow Quartz (Citrine Quartz)

Silicon Dioxide (SiO2)

Quartz (Citrine or Iron-stained variety)

Silicon Dioxide (SiO2)

Healer's Gold (Iron-Stained Quartz Cluster)

Silicon Dioxide with Iron Oxide Coating (SiO2)

Tumbled pale limestone or calcite-rich stone

Limestone, chiefly calcite (CaCO₃); exact identification is uncertain from the photograph

Quartz (Citrine or Iron-stained Quartz)

Silicon Dioxide (SiO2)

Yellow Quartz (Citrine Quartz)

Silicon Dioxide (SiO2)

Black Jasper with Quartz

Silicon Dioxide (SiO2) with impurities

Amethyst (Faceted Gemstone)

Silicon Dioxide (SiO2) with iron impurities

Sandstone

Arenite (primarily SiO2)

Quartz (Citrine or Iron-Stained)

Silicon Dioxide (SiO2)

Tumbled citrine (likely heat-treated amethyst or quartz)

Quartz, SiO₂; yellow coloration from iron impurities or irradiation/heat treatment

Tumbled quartz pebble

Quartz (silicon dioxide, SiO₂)

Weathered iron-rich rock fragment

Likely limonite/goethite-bearing material; exact identification requires testing

Weathered iron-rich rock, likely limonite/goethite-bearing laterite

Limonite–goethite aggregate, commonly approximated as hydrated iron oxides (FeO(OH)·nH₂O)

Quartz Geode (Citrine or Iron-stained Quartz)

Silicon Dioxide (SiO2)

Sandstone

Arenite (SiO2 based)

Yellow Quartz

Silicon Dioxide (SiO2)

Yellow Quartz (Citrine alternative)

Silicon Dioxide (SiO2) with iron impurities

Green Quartz (Prasiolite/Adventurine)

Silicon Dioxide (SiO2) with inclusions

Yellow Quartz (Citrine or Iron-Stained Quartz)

Silicon Dioxide (SiO2)

Yellow Quartz (Citrine-colored Quartz)

Silicon Dioxide (SiO2)

Yellow Quartz Pebble

SiO2 (Silicon Dioxide) with Iron Impurities

Tumbled granitic rock, possibly granite pegmatite

Granite or granitic pegmatite; chiefly quartz, feldspar, and mica, with possible iron-oxide staining

Tumbled honey calcite

Calcite (calcium carbonate, CaCO₃)