Igneous Rock (Volcanic Glass)

Yellow Quartz (Iron-Stained Quartz)

Silicon Dioxide (SiO2) with iron oxide inclusions

Quartz / Milky Quartz

Quartz (Silicon Dioxide - SiO2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Milky Quartz with Iron Staining

Quartz (Silicon Dioxide, SiO2)

Amethyst

Silicon Dioxide with iron impurities (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Amethyst (Quartz Variety)

Amethyst (Silicon Dioxide - SiO2 with ferric iron impurities)

Coarse-grained Granite (Quartz and Feldspar dominated)

Granitoid (KAlSi3O8 – NaAlSi3O3 – CaAl2Si2O8 – SiO2)

Granite

Granite (Mainly Quartz, Feldspar, and Mica)

Smoky Quartz (with possible Feldspar inclusions)

Silicon Dioxide (SiO2)

Quartz Pebble (Iron-stained)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Quartz (Silicon Dioxide - SiO2)

Quartz Vein in Host Rock (Pebble)

Quartz (SiO2) with sandstone or siltstone matrix

Granite

Phaneritic plutonic felsic rock (Quartz, Feldspar, Mica)

Granodiorite with Quartz Veining

Granodiorite (containing Plagioclase Feldspar, Quartz, and Biotite/Hornblende) with Quartz (SiO2) veins

Green Jasper with Quartz veins

Jasper (Silicon Dioxide, SiO2)

Granite (weathered)

Felsic Intrusive Igneous Rock (composed of Quartz, Alkali Feldspar, and Plagioclase)

Granite

Phaneritic Felsic Igneous Rock (composed primarily of Quartz, Feldspar, and Mica)

Obsidian

Volcanic glass (no mineral formula due to amorphous structure, mostly SiO2)

Quartz (Milky/Vein Quartz)

Silicon Dioxide (SiO2)

Smoky Quartz on Matrix

Silicon Dioxide (SiO2) with trace impurities and aluminum inclusions

Granitoid (Granite/Gneiss)

Granitoid silicate rock, primarily quartz and feldspar

Druzy Quartz on Host Rock

Silicon Dioxide (SiO2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Quartz Geode

Silicon Dioxide (SiO2) within a geode

Peridot (Olivine)

Olivine (Magnesium Iron Silicate - (Mg, Fe)2SiO4)

Basalt with Quartz/Calcite Veins

Basalt (Aphanitic Mafic Volcanic Rock) with Silicon Dioxide (SiO2) or Calcium Carbonate (CaCO3) inclusions

Red Jasper

Silicon Dioxide with Iron Oxide inclusions (SiO2 + Fe2O3)

Red Jasper (Heliotrope family variant)

Silicon Dioxide with Hematite inclusions (SiO2 + Fe2O3)

Peridot (Olivine)

Olivine, (Mg,Fe)2SiO4

Rough Dark Green Sapphire

Corundum (Al2O3)

Red Jasper with Quartz Veining

Silicon Dioxide (SiO2) - Microcrystalline Quartz with Iron Oxide impurities (Hematite)

Agate (specifically a Yellow/Honey Agate)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Milky Quartz

Silicon Dioxide (SiO2)

Scoria (often called Lava Rock)

Vesicular Basalt / Scoria

Milky Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)