Synthetic Or Natural Fiber

Tumbled carnelian (probable)

Carnelian, a chalcedony variety of microcrystalline quartz (SiO₂), colored mainly by iron oxides

Polished black obsidian

Volcanic glass, chiefly SiO₂

Tumbled purple quartz, likely amethyst

Quartz (SiO₂), purple variety commonly colored by iron impurities and irradiation

Tumbled jasper (likely brecciated or leopard jasper)

Microcrystalline quartz/chalcedony, SiO₂, with iron-oxide inclusions

Tumbled carnelian (likely agate/chalcedony)

Microcrystalline quartz, SiO₂; reddish color typically from iron oxides

Polished leopard jasper (likely ocean jasper)

Silicified microcrystalline quartz/chalcedony; mainly SiO₂ with iron-oxide inclusions

Tumbled chalcedony (likely agate or common quartz)

Microcrystalline quartz, SiO₂; possible iron-oxide staining

Tumbled agate (likely carnelian or banded chalcedony)

Microcrystalline quartz, SiO₂; chalcedony with iron-oxide coloration

Quartz Pebble (Citrine or Iron-stained Quartz)

Silicon Dioxide (SiO2)

Tumbled jasper (likely picture jasper or iron-rich jasper)

Microcrystalline quartz/chalcedony, SiO₂, colored by iron oxides

Citrine Quartz

Silicon Dioxide (SiO2) with iron impurities

Pearl (as a biogenic mineral/gemstone)

Calcium Carbonate (mostly Aragonite), CaCO3

Turquoise

Turquoise (Hydrated phosphate of copper and aluminium) CuAl6(PO4)4(OH)8·4H2O

Yellow Quartz (Citrine or Quartz Crystal with Iron Inclusions)

Silicon Dioxide (SiO2)

Black Onyx

Cryptocrystalline Quartz (SiO2)

Fossil bivalve shell

Likely fossilized cockle or other marine bivalve; exact genus requires locality and internal features

Pearl

Pearl; primarily aragonite (CaCO₃) in nacre

Yellow Quartz (Citrine or Yellow Jasper)

Silicon Dioxide (SiO2) with iron impurities

Red Quartzite River Pebble

Quartzite (SiO2 with iron oxide inclusions)

Amethyst

Amethyst (Silicon Dioxide, SiO2)

Pearl

Calcium Carbonate (Aragonite) - CaCO3

Turquoise

Hydrated phosphate of copper and aluminium (CuAl6(PO4)4(OH)8·4H2O)

Citrine

Silicon dioxide (SiO2)

Quartz (Milky/Smoky Quartz)

Silicon Dioxide (SiO2)

Yellow Quartz Pebble

Silicon Dioxide (SiO2)

Tumbled milky quartz

Quartz (silicon dioxide, SiO₂)

Yellow Quartz or Citrine Geode/Cluster

Silicon Dioxide (SiO2)

Tumbled feldspar-rich stone (likely granite or pegmatite fragment)

Potassium feldspar, chiefly orthoclase or microcline (KAlSi₃O₈), possibly mixed with quartz

Yellow Quartz (Citrine/Yellow Jasper)

Silicon Dioxide (SiO2)

Tumbled metallic sulfide mineral specimen, likely pyrite-bearing ore

Likely pyrite (FeS₂) with associated sulfides and host rock; exact identification requires testing

Tumbled yellow-brown quartzite or jasper

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

Tumbled prehnite (probable)

Prehnite — Ca₂Al(AlSi₃O₁₀)(OH)₂

Likely tumbled dark volcanic rock

Probably basalt or basaltic andesite; exact identification is uncertain from the image

Yellow Quartz (Citrine or Iron-stained Quartz)

Silicon Dioxide (SiO2)

Goldstone (Brown/Gold variety)

Aventurine Glass (SiO2 with Copper inclusions)

Glass Nugget (Tumbled Glass)

Amorphous Silicon Dioxide (SiO2) with additives

Yellow Quartz Pebble (Citrine or Iron-Stained Quartz)

Silicon Dioxide (SiO2)

Tumbled quartz-rich pebble

Quartz (SiO₂), possibly iron-stained or included quartz

Tumbled jasper or iron-rich chert

Microcrystalline quartz (SiO₂) with iron-oxide inclusions

Milky quartz pebble

Quartz (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