Igneous Rock (Volcanic Glass)

Clear Quartz

Quartz (Silicon Dioxide, SiO2)

Sandstone (Red)

Arenite (primarily Quartz, SiO2, with Iron Oxide cement)

Pink Granite

Phaneritic Felsic Igneous Rock (Rich in K-Feldspar)

Flower Agate

Chalcedony (SiO2) with Scolecite/Opaque inclusions

Mahogany Obsidian

Volcanic Glass with Hematite/Magnetite inclusions (SiO2 + Fe2O3)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Petrified Wood

Silicified Wood (SiO2)

Carnelian Agate

Chalcedony (Silicon Dioxide, SiO2) with Iron Oxide impurities

Basalt

Basalt

Clear Quartz

Silicon Dioxide (SiO2)

Obsidian

Volcanic glass (SiO2 - Silicon Dioxide with impurities)

Quartz (Iron-stained)

Silicon Dioxide (SiO2)

Quartz

Quartz (SiO2)

Basalt

Basalt (dominated by plagioclase feldspar and pyroxene minerals)

Epidote

Epidote (formula: Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH))

Milky Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Smoky Quartz in Matrix

Silicon dioxide (SiO2) within Pegmatite/Gneiss

Pink Granite

Phaneritic Plutonic Igneous Rock (high K-feldspar)

Diorite (possibly fine-grained variety or a related intermediate intrusive rock like a felsic gabbro or a dark granodiorite)

Diorite (Igneous rock, intrusive, intermediate composition)

Quartz / Common Opal Transition

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Amethyst

Silicon Dioxide with Iron impurities (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Granite

Phaneritic Plutonic Felsic Rock (SiO2, KAlSi3O8, NaAlSi3O8, CaAl2Si2O8)

Yellow Quartz (Chalcedony or Agate)

Silicon Dioxide (SiO2)

Scoria (Red Lava Rock)

Scoria (Vesicular Basalt/Andesite)

Blue Sapphire

Corundum (Al2O3 with trace Titanium and Iron)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Quartz Pebble (with Mica or Iron staining)

Silicon Dioxide (SiO2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Clear Quartz (Rock Crystal)

Quartz (Silicon Dioxide, SiO2)

Chalcedony in Host Rock

Chalcedony (SiO2)

Amethyst Lace Agate / Banded Amethyst

Silicon Dioxide (SiO2) with Fe3+ impurities

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Diorite (Salt and Pepper Rock)

Diorite (comprising Plagioclase Feldspar, Hornblende, and Biotite)

Diorite (Salt and Pepper Rock)

Phaneritic Plutonic Diorite; chemical composition roughly 52-63% silica (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Chert Pebble/Nodule

Chert (a microcrystalline or cryptocrystalline sedimentary form of quartz, SiO2)

River Quartz Pitting/Cobble

Silicon Dioxide (SiO2)

Obsidian

Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)

Yellow Jasper

Silicon Dioxide (SiO2)

White Quartz Pebble

Quartz (Silicon Dioxide, SiO2)