Basalt

Bauxite

Hydrated Aluminum Oxides (primarily Gibbsite Al(OH)3, Boehmite γ-AlO(OH), and Diaspore α-AlO(OH))

Eclogite

Eclogite (Omphacite-Garnet rock)

Greenschist

Greenschist (Chlorite Schist)

Blue Chalcedony

Silicon Dioxide (SiO2)

Amethyst

Amethyst (Silicon Dioxide - SiO2 with iron impurities)

Carnelian Agate

Silicon Dioxide (SiO2) - Variety of Chalcedony

Amethyst (Cabochon)

Silicon Dioxide (SiO2) with iron impurities

Epidosite (Epidote-Quartz rock)

Epidote-rich hydrothermal rock

Gabbro

Gabbro

Labradorite

(Ca, Na)(Al, Si)4O8 (Plagioclase Feldspar)

Ruby

Corundum (Al2O3 with Chromium traces)

Banded River Cobble with Mafic Dike

Hydrothermally altered Graywacke or Sandstone with Mafic Intrusion

Labradorite

Labradorite (Plagioclase Feldspar Series) - (Ca, Na)(Al, Si)4O8

Labradorite (Feldspar)

Labradorite: (Ca,Na)(Al,Si)4O8

Crushed Stone / Gravel

Aggregatus saxum (variable mineral composition)

Banded Agate (Tumbled)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Labradorite

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

Chalcedony in Matrix

Silicon Dioxide (SiO2)

Greenstone

Greenschist

Green Banded Agate

Agate (Cryptocrystalline variety of Quartz, SiO2)

Amethyst Quartz Crust

Crystalline Silicon Dioxide with Iron impurities (SiO2)

Ruby, Emerald, and Sapphire (Corundum and Beryl)

Corundum (Al2O3) and Beryl (Be3Al2Si6O18)

Magnetite

Magnetite (Fe3O4)

Chalcedony (Botryoidal or Geode form)

Silicon Dioxide (SiO2)

Epidosite

Epidosite (predominantly Epidote {Ca2Al2Fe3+Si3O12(OH)} and Quartz {SiO2})

Amethyst (Rough)

Silicon Dioxide (SiO2) with iron impurities

Blue Sapphire

Corundum (Al2O3 with trace Titanium and Iron)

Amethyst

Silicon dioxide / Violet Quartz (SiO2)

Green Apophyllite on Stilbite

Fluorapophyllite-(K) [(KCa4Si8O20F)·8H2O] and Stilbite [NaCa4(Si27Al9)O72·28H2O]

Carnelian Agate

Silicon Dioxide (SiO2) - Chalcedony variety

Olivine (Peridot)

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

Agate

Silicon Dioxide (SiO2) - Cryptocrystalline Chalcedony

Amethyst Quartz

Silicon Dioxide (SiO2) with iron impurities

Carnelian

Carnelian (Silica, SiO2)

Ruby (Corundum)

Al2O3 (Aluminium oxide with Chromium impurities)

Epidosite (Unakite-related)

Epidosite (predominantly Epidote, Ca2(Al2,Fe3+)(SiO4)3(OH))

Amethyst

Amethyst (Silicon Dioxide with iron impurities), SiO2

Andesite Porphyry

Porphyritic Andesite (Intermediate volcanic rock)

Druzy Quartz on Matrix

Silicon Dioxide (SiO2)

Scoria with Calcite Infills

Vesicular Basalt with secondary Calcification (CaCO3)

River Pebble (Basalt/Greywacke)

Weathered Basalt or Fine-Grained Greywacke

Wishing Stone (Quartz-Veined Basalt)

Amygdaloidal Basalt with Quartz (SiO2) vein