Not A Rock Or Mineral

Polished Black Obsidian

Volcanic Glass (70-75% SiO2)

Vesicular Basalt (or Scoria)

Vesicular Basalt

Iron Slag

Anthropogenic Ferro-silicate

Tumbled brecciated jasper

Silica-rich microcrystalline quartz/chalcedony (SiO₂), with iron-oxide and other mineral inclusions

Iron-stained Quartz

Silicon Dioxide with Iron Oxide (SiO2 + Fe2O3/FeO(OH))

Sandstone Pebble

Arenite (SiO2 dominated with iron oxide)

Assorted Decorative Tumbled Stones (Quartz, Sodalite, Aventurine, Calcite)

Mixed Silicates and Carbonates (SiO2, Na8(Al6Si6O24)Cl2, CaCO3)

Granite / Igneous Rock Specimen

Phaneritic Igneous Rock

Quartz (River Pebble)

Silicon Dioxide (SiO2)

Kambaba Jasper

Stromatolite / Fossilized Algae (Rhyolitic structure)

Quartz-rich Diorite

Diorite (Phaneritic intermediate igneous rock)

Sandstone (likely Iron-rich or Arkosic)

Arenite (SiO2 with FeO(OH) or Fe2O3 staining)

Brachiopod Fossil in Matrix

Phylum Brachiopoda

Gneiss

Gneiss

Milky Quartz with Iron Staining

Silicon Dioxide (SiO2)

Quartz Druzy

Silicon Dioxide (SiO2)

Quartz in Matrix (or Quartz Vein Rock)

Silicon Dioxide (SiO2) with host rock

Amphibolite / Biotite Schist

Amphibolite (rich in Hornblende and Plagioclase feldspar)

Carnelian Agate

Silicon Dioxide (SiO2) with iron oxide impurities

Fossilized Sea Urchin (Echinoid)

Echinoidea (Class) - likely replaced by Calcite or Quartz

Granite

Granite (Alkali-feldspar, Quartz, and Plagioclase composition)

Limestone with Fossil Fragment

Sedimentary carbonate rock (CaCO3)

Basalt

Extrusive mafic volcanic rock

Basalt (with possible Olivine inclusions)

Mafic Igneous Rock (primarily Plagioclase and Pyroxene)

Sandstone

Arenite

Granite

Intrusive igneous rock

Dalmation Stone

Dalmation Jasper (Igneous microcrystalline quartz with arfvedsonite)

Sandstone (River Cobble)

Clastic Sedimentary Rock (primarily Quartz with Feldspar)

Boulder Opal

Hydrated amorphous silica (SiO2·nH2O) in ironstone matrix

Basalt with Quartz/Plagioclase Inclusions

Mafic volcanic rock (Basaltic)

Vesicular basalt (likely scoria)

Basaltic volcanic rock; chiefly plagioclase, pyroxene, and olivine, with possible volcanic glass

Schist

Mica Schist

Sandstone (Sedimentary Rock)

Arenite (SiO2 based)

Green Sandstone Pebble (River/Beach Pebble)

Glauconitic Sandstone

Sandstone (Ferruginous)

Arenite (primarily SiO2 with iron oxide Fe2O3 cement)

Quartz Vein in Host Rock

Silicon Dioxide (SiO2) vein cutting through host rock

Coarse-grained Granite or Gneiss

Granitic intrusive rock

Red Sandstone Pebble

Sedimentary Quartz Arenite / Arkose

Mica Schist

Mica Schist (predominantly Muscovite or Biotite sheet silicates)

Garnet Schist

Garnet-bearing Mica Schist (variety of compositions, often Al2SiO5 with X3Y2(SiO4)3)

Malachite Coating on Host Rock

Malachite [Cu2CO3(OH)2]

Basalt

Basalt (Mafic volcanic rock)