Tektite (Natural Glass)

Quartz–feldspar pegmatite with garnet

Granitic pegmatite; chiefly quartz (SiO₂), feldspar, mica, and reddish-brown almandine garnet

Tumbled chalcedony (likely milky quartz)

Chalcedony, cryptocrystalline SiO₂; possibly quartz-rich chert

Likely weathered quartz-rich stone

Indeterminate; possibly quartz-bearing granite or milky quartz

Likely weathered sandstone or iron-rich chert fragment

Indeterminate; probable quartz-rich sandstone (SiO₂) with iron-oxide cement, possibly chert

Amethyst crystal cluster

Amethyst, purple quartz (SiO₂) colored mainly by iron impurities and irradiation

Glass / Silicon Dioxide (Man-made)

SiO2 (Amorphous Silicon Dioxide)

Raw greenish-blue quartz-bearing mineral specimen

Likely fluorite or chalcedony/quartz; exact identification requires hardness and crystal tests

Jasper

Silicon dioxide (SiO2) with iron oxide inclusions

Red Jasper

Jasper (Silicon Dioxide with Iron Oxide inclusions, SiO2)

Red Jasper (Tumbled)

Silicon Dioxide (SiO2) with iron oxide inclusions

Jasper with Iron Staining

Silicon Dioxide (SiO2) with impurities

Yellow jasper (likely iron-stained chert or quartzite)

Microcrystalline quartz, SiO₂, colored by iron oxides/hydroxides

Amethyst (Scepter Quartz)

Silicon Dioxide (SiO2) with Iron impurities

Quartzite river stone

Quartzite (mostly SiO2)

Small rounded pebble, likely quartz-rich stone

Indeterminate from photograph; possibly microcrystalline quartz (SiO₂) or a weathered silicate pebble

Milky quartz (quartz crystal)

Quartz, silicon dioxide (SiO₂)

Amethyst-bearing quartz (rough/tumbled fragment)

Quartz, SiO₂; purple coloration from irradiation and trace iron

Yellow Chert (Jasper)

Cryptocrystalline Quartz (SiO2)

Chert (Hagstone/Adder Stone)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Polished/patinated jasper slab

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

Apache Tear (Obsidian)

Obsidian / Amorphous Volcanic Glass (primarily SiO2)

Amethyst Quartz (Tumbled)

Amethyst (Silicon Dioxide with iron impurities, SiO2)

Granite

Phaneritic Felsic Igneous Rock

Red Jasper

Silicon Dioxide (SiO2) with iron oxide inclusions

Jasper

Silicon Dioxide (SiO2)

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Jasper

Jasper (Silicon Dioxide, SiO2 with iron inclusions)

Black Veined Jasper (Spiderweb Jasper)

Silicon Dioxide (SiO2)

Rose Quartz

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

Jasper (Green)

Silicon Dioxide (SiO2) with impurities

Yellow Jasper

Silicon Dioxide (SiO2) with Goethite/Iron oxide inclusions

Jasper (Iron-stained Chert)

Silicon Dioxide (SiO2) with impurities of Iron Oxide

Granite pebble

Granite, typically quartz–feldspar–mica aggregate

Tumbled jasper or iron-rich chalcedony

Microcrystalline quartz (SiO₂), likely colored by iron oxides

Weathered quartz-rich rock, possibly chert or milky quartz

Mostly microcrystalline or crystalline quartz (SiO₂), identification uncertain from photograph

Orbicular jasper (picture jasper)

Silicified volcanic or sedimentary rock; chiefly microcrystalline quartz (SiO₂) with iron-oxide pigments

Obsidian arrowhead flakes

Volcanic glass; primarily silica-rich rhyolitic composition (approximately 70–75% SiO₂)

Rounded iron-rich pebble

Likely hematite/goethite-bearing quartzite or ironstone; exact identification requires testing

Pink granite / granitic pegmatite

Coarse-grained felsic granitoid; chiefly quartz (SiO₂), potassium feldspar, plagioclase, and minor mica/iron oxides

Biotite-rich granite or granitic gneiss

Granite, chiefly quartz + feldspar + biotite mica; possibly weakly gneissic

Unidentified weathered rock fragments

Likely mixed silicate rocks; specific identification requires testing

Ferruginous Quartz (Red Quartz)

Silicon Dioxide (SiO2) with Hematite/Limonite impurities