Basalt

Diabase (also known as Dolerite)

Diabase

Peridot

Olivine ((Mg, Fe)2SiO4)

Olivine Peridotite

Peridotite (comprising Olivine (Mg,Fe)2SiO4 and Pyroxene)

Amethyst

Amethyst (Silicon Dioxide - SiO2 with Iron impurities)

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Amygdaloidal Basalt

Amygdaloidal Basalt (Host rock) with Quartz or Calcite amygdules

Prehnite

Prehnite (Ca2Al2Si3O10(OH)2)

River Rock (Basalt)

Basalt (SiO2 range: 45-52%)

Olivine (Peridot)

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

Basalt (Stream-worn Cobble)

Mafic Igneous Rock (primarily Plagioclase and Pyroxene)

Amygdaloidal Basalt

Amygdaloidal Basalt (with secondary mineral infilling)

Amygdaloidal Basalt with Agate/Chalcedony Infills

Amygdaloidal Basalt (Composition: SiO2 and (Mg,Fe)2SiO4 in matrix; SiO2 in amygdule)

Basalt with Magnetite

Crystalline Basalt (Primarily Plagioclase and Pyroxene) with Magnetite (Fe3O4)

Basalt Pebble with Epidote/Olivine

Vitreous Basalt (SiO2 with Ca/Mg/Fe silicates)

Opal

Hydrated amorphous silica (SiO2·nH2O)

Labradorite (Dark or Black variety)

Labradorite (member of Plagioclase Feldspar group), (Na,Ca)(Si,Al)4O8

Greenschist

Greenschist facies rock (containing chlorite, actinolite, and epidote)

Porphyritic Basalt

Porphyritic Fine-grained Mafic Volcanic Rock

Vesicular Basalt with Secondary Mineral Inclusions

Aphanitic Mafic Igneous Rock (primarily Plagioclase and Pyroxene)

Olivine (Peridot when gem-quality)

Magnesium Iron Silicate (Mg,Fe)2SiO4

Basalt Riverstone

Basalt (Aphanitic Mafic Volcanic Rock)

Basalt (River Rock Cobble)

Extrusive mafic igneous rock

Vesicular Basalt with Amygdaloidal Infill

Basalt (Mafic Extrusive Igneous Rock)

Basalt (with possible weathering or secondary mineral crust)

Basalt (Aphanitic Mafic Igneous Rock)

Basalt (Beach Pebble)

Extrusive mafic volcanic rock

Diabase (Greenstone)

Diabase (also known as Dolerite)

Basalt Pebble

Aphanitic Mafic Igneous Rock

Basalt (Vesicular or Scoriaceous)

Aphanitic Mafic Volcanic Rock

Basalt with Hematite staining

Extrusive mafic igneous rock with Fe2O3

Vesicular Basalt

Extrusive mafic igneous rock

Basalt River Pebble

Mafic Igneous Rock (Fine-grained Basalt)

Granodiorite Pebble

Granodiorite

River Pebble (Basalt)

Basalt (Aphanitic Mafic Igneous Rock)

Basalt River Cobble

Basalt (Aphanitic Mafic Volcanic Rock)

Vesicular Basalt with Xenocrysts

Mafic Igneous Plutonic/Extrusive Complex

Basalt with Iron Oxidation

Mafic Igneous Rock (primarily Plagioclase and Pyroxene)

Basalt (Vesicular)

Basalt (Extrusive Mafic Igneous Rock)

Crushed Rock (Basalt)

Basalt (Aphanitic Mafic Igneous Rock)

Basalt with Quartz Veins

Basalt (SiO2 range 45-52%)

Basalt (River Stone)

Mafic volcanic rock

Amygdaloidal Basalt

Amygdaloidal Basalt (Mafic Extrusive volcanic rock)

Andesite

Andesite (Intermediate Extrusive Volcanic Rock)