Mineral, Part Of A Rock

Petrified Wood

Silicified Wood (SiO2)

Fossilized echinoid (sea urchin), likely a sand dollar fragment or small regular urchin

Echinodermata; commonly Clypeasteroida or Echinoida, preserved mainly as calcite (CaCO₃)

Quartz fragment

Quartz (silicon dioxide, SiO₂)

Fossilized sea urchin test (likely sand dollar fragment or echinoid fossil)

Echinoidea; calcitic echinoderm skeleton, chiefly CaCO₃

Polished brown gemstone, likely jasper or bronzite

Jasper: microcrystalline SiO₂; possible bronzite: (Mg,Fe)SiO₃

River Pebble (Brecciated Chert/Siltstone)

Silicon Dioxide (SiO2) with mineral inclusions

Small faceted dark gemstone, possibly spinel or sapphire

Uncertain; candidates include MgAl₂O₄ spinel or corundum (Al₂O₃) sapphire

Weathered ironstone concretion (probable limonite/goethite nodule)

Limonite-goethite-rich iron-oxide concretion; chiefly FeO(OH)·nH₂O

Chrysocolla

Hydrated copper silicate, (Cu,Al)2H2Si2O5(OH)4·nH2O

Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Weathered, iron-stained quartzite pebble

Quartzite; predominantly microcrystalline quartz (SiO₂) with iron-oxide staining

Milky Quartz Pebble

Crystalline Silicon Dioxide (SiO2)

Tektite (Indochinite)

Tektite (High-silica natural glass, primarily SiO2 with Al2O3)

Chalcedony (Botryoidal/Chalcedony Rose)

Silicon Dioxide (SiO2)

Sand Tiger Shark Tooth (Fossil)

Carcharias taurus (fossilized dentin/enameloid)

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Shark Tooth Fossil

Chondrichthyes fossil

Emerald

Beryl (Be3Al2(SiO3)6)

Rounded white pebble, likely quartzite or limestone

Probable quartzite (microcrystalline quartz, SiO₂) or calcitic limestone (CaCO₃)

Iron-stained quartzite or quartz-rich sandstone

Quartzite; predominantly quartz (SiO₂) with iron-oxide staining

Rounded sandstone pebble

Quartz-rich sandstone, likely arenite

Weathered graywacke or sandstone cobble

Lithic/feldspathic sandstone; exact identification requires a fresh break or thin section

Quartz pebble

SiO2

Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Quartz (likely a weathered/tumbled piece)

Quartz (SiO₂)

Rounded gray pebble, likely basalt or andesite

Fine-grained mafic to intermediate volcanic rock; exact identification requires testing

Iron Slag

Vitreous glassy waste (Fe-Si-Al-Ca compounds)

Fossilized Shark Tooth

Fossilized Elasmobranchii tooth (likely Odontaspis or Carcharias)

Quartz with Mica (Schist/Pegmatite fragment)

Silicon Dioxide (SiO2) with Phyllosilicates (KAl2(AlSi3O10)(OH)2)

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

Magnetite-rich black sand

Magnetite (Fe₃O₄), likely mixed with other heavy minerals

Stilbite

Stilbite-Ca (NaCa4Mg[Al9Si27O72]·28H2O)

Granite (Background) and Quartzite/River Pebble (Foreground Heart)

Phaneritic Felsic Igneous Rock (Granite background)

Petoskey Stone

Hexagonaria percarinata (Fossilized Rugose Coral)

Fossil brachiopod shell

Likely spiriferid or strophomenid brachiopod; calcium carbonate (primarily calcite)

Pink Granite

Granite (rich in Potassium Feldspar/Orthoclase)

Amethyst

Quartz (Silicon Dioxide with iron impurities), SiO2

Quartz (Milky or Iron-Stained)

Silicon Dioxide (SiO2)

Gold Nugget

Native Gold (Au)

Likely amethyst crystal fragment

Quartz, SiO₂; purple coloration from iron-related defects and irradiation

Green agate (polished bead)

Chalcedony, microcrystalline quartz (SiO₂)