Tektite (Natural Glass)

Clear Quartz Crystal

Quartz (Silicon Dioxide, SiO2)

Natural or Cultured Pearl

Calcium Carbonate (Aragonite and Conchiolin), CaCO3

Chalcedony (specifically Agate or Water-worn Quartzite)

Silicon Dioxide (SiO2)

Blue Impression Jasper beads

Impression jasper (microcrystalline quartz/chalcedony), chiefly SiO₂, with iron-oxide and other mineral inclusions

Smoky Quartz

Silicon Dioxide (SiO2)

Heat-Treated Citrine (Amethyst Geode Fragment)

Silicon Dioxide (SiO2) with iron impurities

Yellow Quartz

Silicon Dioxide (SiO2)

Amethyst

SiO2 (Amethyst is a variety of Quartz)

Amethyst

Silicon dioxide (SiO2)

Tumbled quartz-rich pebble

Quartz (SiO₂), likely with iron-oxide staining and minor feldspar

Weathered limestone pebble

Limestone, primarily calcite (CaCO₃)

Blue chalcedony (likely dyed or coated)

Chalcedony, microcrystalline quartz (SiO₂)

Yellow Quartz Pebble

Silicon Dioxide (SiO2)

Tumbled jasper or chert

Microcrystalline quartz (SiO₂), possibly iron-bearing jasper

Emerald

Beryl (Be3Al2Si6O18) with trace amounts of Chromium and/or Vanadium

Diamond

Diamond (C - Pure Carbon)

Quartzite

Quartzite (composed primarily of SiO2)

Ferruginous Slag (Iron Smelting Byproduct)

Fused Silicate Scoria (Amorphous mixture of FeO, SiO2, and CaO)

Smoky Quartz

SiO2 (Silicon Dioxide)

Smoky Quartz with Hematite Inclusions

Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3) inclusions

Amethyst cluster

Amethyst, purple quartz (SiO₂)

Quartz (Iron-stained)

Silicon Dioxide (SiO2)

Iron-Stained Quartz Pebble

Silicon Dioxide (SiO2) with Hematite/Limonite impurities

Quartz heart (likely milky/included quartz)

Quartz, silicon dioxide (SiO₂)

Clear Quartz Crystal

Silicon Dioxide (SiO2)

Polished mahogany obsidian (likely)

Volcanic glass; primarily silica-rich rhyolitic glass (SiO₂), with iron oxides

Green Jasper

Silicon Dioxide (SiO2) with iron and silicate inclusions

Tumbled chert or flint pebble

Microcrystalline quartz (SiO₂), likely chert; exact variety uncertain from the image

Tumbled jasper pebble

Jasper, microcrystalline quartz (SiO₂) with iron-oxide impurities

Tumbled brecciated jasper

Silica-rich microcrystalline quartz/chalcedony (SiO₂), with iron-oxide and other mineral inclusions

Granite (Background) and Quartzite/River Pebble (Foreground Heart)

Phaneritic Felsic Igneous Rock (Granite background)

Tumbled red jasper

Jasper, microcrystalline quartz (SiO₂) colored mainly by iron oxides

Sandstone

Sandstone (lithified sand)

Smoky Quartz

Smoky Quartz (Silicon Dioxide, SiO2)

Amethyst

Quartz (Silicon Dioxide with Iron impurities), SiO2

Jasper and Yellow Chert (Tumbled)

Microcrystalline Quartz (SiO2)

Tumbled quartz-rich pebble

Microcrystalline quartz (SiO₂), possibly weathered chert or chalcedony

Clear Quartz

SiO2 (Silicon Dioxide)

Amethyst Cluster

Silicon Dioxide (Quartz variety: Amethyst), SiO2

Smoky Quartz

Smoky Quartz (Silicon Dioxide, SiO2)

Yellow Quartz Pebble

Silicon Dioxide (SiO2)

Amethyst (Quartz Cluster)

Silicon Dioxide (SiO2) with iron impurities