Igneous And Mineral

Mahogany Obsidian

Volcanic glass (SiO2 with Hematite or Magnetite inclusions)

Vesicular Basalt (River Pebble)

Vesicular Basalt

Granitic Pegmatite

Coarse-grained Granite (KAlSi3O8 + SiO2)

Amazonite

Potassium feldspar (Microcline) - K(AlSi3O8)

Carnelian

Carnelian Chalcedony (SiO2 with Iron Oxide impurities)

Quartz (Clear Quartz/Rock Crystal)

Silicon Dioxide (SiO2)

Granitic Pegmatite with Schorl

Granitic Pegmatite (NaAlSi3O8, KAlSi3O8, SiO2) with Schorl (NaFe3Al6(BO3)3Si6O18(OH)4)

Sodalite

Sodalite (Na8Al6Si6O24Cl2)

Obsidian

Obsidian (Volcanic Glass, primarily SiO2)

Granite

Phaneritic Intrusive Igneous Rock (primarily composed of SiO2, Al2O3, K2O, Na2O)

Basalt River Pebble

Basalt (Aphanitic Mafic Volcanic Rock)

Obsidian

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

Ruby (Corundum)

Corundum (Aluminum Oxide with Chromium), Al2O3:Cr

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Pink Granite

Felsic intrusive igneous rock (composition: SiO2 and Al2O3)

Granodiorite

Granodiorite (Na,Ca)(Si,Al)4O8

Basalt with Iron Oxidation

Amygdaloidal Basalt (silicate rock primarily plagioclase, pyroxene, and olivine)

Granodiorite (foreground) and Rose Quartz (background)

Granodiorite / Quartz (SiO2)

Granodiorite / Granite

Granodiorite (containing Quartz SiO2, Plagioclase Feldspar, and Biotite)

Vesicular Basalt with Quartz/Chalcedony

Vesicular Basalt (primarily Plagioclase, Pyroxene, and Olivine with SiO2 infill)

Amethyst

Quartz variety; SiO2 (Silicon Dioxide)

Amethyst

Amethyst (Silicon Dioxide with iron impurities, SiO2)

Milky Quartz

Quartz (Silicon Dioxide - SiO2)

Quartz on Basalt

Silicon Dioxide (SiO2) on Mafic Igneous Rock

Greenschist (Chlorite Schist)

Greenschist (containing chlorite, actinolite, and epidote)

Granite (Specimen: Logan Rock)

Phaneritic plutonic igneous rock (mainly Quartz, Feldspar, and Mica)

Milky Quartz (Water-worn Pebble)

Quartz (Silicon Dioxide, SiO2)

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Basalt (with possible weathering or secondary mineral crust)

Basalt (Aphanitic Mafic Igneous Rock)

Basalt with Weathering Crust

Extrusive mafic volcanic rock

Obsidian

Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)

Quartz Pebble

Silicon Dioxide (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Yellow Quartz (Citrine or Quartzite Pebble)

Silicon Dioxide (SiO2)

Quartz (Iron-stained)

Silicon Dioxide (SiO2) with hematite/limonite inclusions

Ruby (Pink to Red Corundum)

Al2O3 (Corundum with Chromium impurities)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Smoky Quartz

Silicon Dioxide (SiO2) with aluminum impurities and natural radiation

Gold

Native Gold (Au)

Banded Agate (Jasper-Agate)

Silicon Dioxide (SiO₂)

Peridot (Olivine)

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

Yellow Quartz (Citrine Quartz)

Silicon Dioxide (SiO2)