Man Made Object (Coin)

Milky Quartz (with trace inclusions)

Silicon Dioxide (SiO2)

Quartz (likely a form of massive or vein quartz)

Quartz (SiO₂)

Mineral

Chert (Yellow Jasper variant)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Pebble (likely a type of sandstone or quartzite pebble)

Clastic Sediment (specifically, a rudite-sized clast). If the pebble is composed of a specific rock type, its scientific name would be that rock type (e.g., 'Quartzite pebble', 'Granite pebble', 'Chert pebble'). Given its appearance, it is likely a metamorphic quartzite pebble or a hard sandstone pebble.

Sedimentary rock

Basaltic Tuff / Volcanic Breccia

Pyroclastic Breccia / Lithic Tuff

Sandstone (with minor quartz and possible clay components)

Clastic Sedimentary Rock (SiO2 dominated)

Petrified Wood

Silicified wood (Quartz variant, SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Quartzite

Metamorphosed Quartz Sandstone (SiO2)

Fossilized Coral (Petoskey Stone or Rugose Coral)

Antophyllum (Hexagonaria) or Scleractinia (CaCO3)

Citrine

Citrine (Silicon Dioxide, SiO2)

Citrine Quartz Sphere

Silicon Dioxide (SiO2)

Scoria (Red Lava Rock)

Scoria

Yellow Citrine Quartz

Silicon Dioxide (SiO₂)

River Quartz / Quartzite Pebbles

Quartzite (primarily Silicon Dioxide, SiO2)

Agate (Nodule/Chert)

Silicon Dioxide (SiO2)

Chert (often called Flint)

Chert (Cryptocrystalline Silica, SiO2)

Organic Gemstone (not a rock)

Amber (Cherry or Red variety)

Succinite (with various trace amounts of organic compounds)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Sandstone (Quartzite-rich)

Clastic sedimentary rock (primarily SiO2)

Quartz

Quartz (SiO2, Silicon Dioxide)

Mineral

Imperial Jasper

Silicon Dioxide (SiO2) - Microcrystalline Quartz with Mineral Inclusions

Sedimentary

Nephrite Jade

Nephrite (Ca2(Mg, Fe)5Si8O22(OH)2), a variety of Actinolite-Tremolite

Ammonite Fossil

Ammonitida (Extinct subclass of Cephalopoda)

Quartz (Milky/Common)

Silicon Dioxide (SiO2)

Basaltic Scoria

Scoria (Vesicular Basalt/Andesite)

Amber

Succinite (with a generalized formula of C10H16O)

Marble

Metamorphosed Limestone (principally CaCO3)

Agate (Dyed High-Grade Polished Slice)

Silicon dioxide (SiO2), Chalcedony crystal variety

Greenstone / Greenstone Pebble

Greenschist (metamorphosed basalt or gabbro)

Jadeite Jade

Jadeite (NaAlSi2O6)

Sodalite

Sodalite (Na8(Al6Si6O24)Cl2)

Mineral

Yellow Jasper

Silicon Dioxide (SiO2) with iron hydroxides (Goethite)

Basalt (River Rock pebble)

Basalt (a mafic extrusive igneous rock)

Orthoclase Feldspar

Orthoclase (KAlSi3O8)

Peacock Ore

Bornite (Cu5FeS4)

Basalt

Basalt (Aphanitic Mafic Volcanic Rock)

Igneous

Obsidian

Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Clear Quartz

Silicon Dioxide (SiO2)

Red Jasper

Silicon Dioxide (SiO2)