Sedimentary Or Igneous (Host Environment)

Dark Igneous Rock (Likely Basalt or Diabase)

Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.

Pyrite

Iron Sulfide (FeS2)

Basalt River Stone

Extrusive mafic igneous rock

Green Aventurine and Clear Quartz

Green Aventurine (Silicon Dioxide - SiO2 with Fuchsite inclusions); Clear Quartz (Silicon Dioxide - SiO2)

Chert (and Limestone Pebbles)

Silicon Dioxide (SiO2) / Sedimentary Microcrystalline Quartz

Sandstone (with banding/weathering)

Clastic Sedimentary Rock (primarily SiO2)

Greenstone

Greenschist / Greenstone (containing Chlorite, Epidote, Actinolite)

River Stone (Basalt or fine-grained Schist)

Mafic Igneous Rock / Volcanic Basalt

Chert with Druzy Quartz Geode

Microcrystalline Quartz (SiO2)

Chert (specifically Agate/Jasper variety)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Chert Nodule (Commonly known as Flint or River Rock)

Silicon Dioxide (SiO2)

Turquoise

CuAl6(PO4)4(OH)8·4H2O (Hydrous phosphate of copper and aluminium)

Milky Quartz

Silicon Dioxide (SiO2)

Granite Water-Worn Pebble

Phaneritic Felsic Igneous Rock

Basalt (River Rock Cobble)

Extrusive mafic igneous rock

Basalt (Beach Pebble)

Extrusive mafic igneous rock

Basalt Pebble

Extrusive mafic igneous rock

Basalt River Cobble

Basalt (Mafic Extrusive Igneous Rock)

Milky Quartz Pebble

Silicon Dioxide (SiO2)

Milky Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Milky and Smoky Quartz Cobble

Silicon Dioxide (SiO2)

White Quartz Pebble

Silicon Dioxide (SiO2)

Milky Quartz Pebble

Silicon Dioxide (SiO2)

Basalt (tumbled/water-worn)

Extrusive mafic igneous rock

Basalt Pebble

Extrusive Mafic Igneous Rock

Sandstone (likely Graywacke or Lithic Arenite)

Clastic sedimentary rock predominantly composed of silicate grains

Granite River Pebble

Phaneritic Felsic Igneous Rock (Granite)

Basalt

Basalt (Aphanitic Mafic Igneous Rock)

Granite Pebble

Granite (Phaneritic Acidic Igneous Rock)

Quartz Geode

Crystalline Silicon Dioxide (SiO2) in sedimentary/volcanic host

Quartz Vein in Host Rock

Silicon Dioxide (SiO2) within Sedimentary/Metamorphic Matrix

Chert (Yellow Jasper/Flint)

Silicon Dioxide (SiO2)

Chert (Fossiliferous)

Chert (Cryptocrystalline Silica/SiO2)

Basalt

Mafic Igneous Rock (composed primarily of plagioclase, pyroxene, and olivine)

Spinifex Textured Komatiite

Ultramafic Komatiite (with Olivine Spinifex)

Sandstone (Ferruginous)

Arenite with Iron Oxide matrix

Pyrite

Iron Sulfide (FeS2)

Blue Apatite

Apatite (Calcium Phosphate) - Ca5(PO4)3(F,Cl,OH)

Quartz Pebble

Silicon Dioxide (SiO2)

Chert (Jasper/Agate variety)

Cryptocrystalline Quartz (SiO2)

Jasper (Picture Jasper variety)

Silicon Dioxide (SiO2) with impurities

Chert Pebble

Microcrystalline or Cryptocrystalline Quartz (SiO2)