Mineraloid (Human Made Geological Specimen)

Snowflake Obsidian

Obsidian with Cristobalite inclusions (70–75% SiO2)

Red Sandstone (Iron-rich)

Ferruginous Sandstone (variable formula, primarily SiO2 + Fe2O3)

Fossilized Horn Coral

Order Rugosa (Rugose Coral)

Ammonite Fossil

Ammonoidea (typically preserved as Calcite CaCO3 or Pyrite FeS2)

Basalt with Limonite stains

Extrusive mafic igneous rock; Limonite (FeO(OH)·nH2O)

Wishing Stone with Quartz Veins

Quartzite or Quartz-veined Metamorphic Rock (composed mainly of SiO2)

Ironstone Concretion (Moqui Marble)

Iron Oxide Concretion (Fe2O3 / FeO(OH) mixed with SiO2)

Heulandite with Stilbite

Heulandite-Ca ((Ca,Na)2-3Al3(Al,Si)2Si13O36·12H2O) and Stilbite-Ca (NaCa4(Si27Al9)O72·28H2O)

Septarian Nodule (Dragon Stone) sphere

Septarian concretion (Calcite, Aragonite, and Limestone)

Limonite-pseudomorph after Pyrite (Prophecy Stone)

Goethite and Limonite secondary minerals (FeO(OH)·nH2O) replacing Pyrite (FeS2)

Sandstone (lithic/greywacke variant)

Clastic sedimentary rock (primarily SiO2 with rock fragments)

Orthoclase Feldspar

KAlSi3O8 (Potassium Aluminum Silicate)

Granite featuring Quartz Vein

Granite with hydrothermal silica (SiO2) intrusion

Granite

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

Agate (specifically, likely a geode slice or nodule)

Agate (a variety of Chalcedony, with chemical formula SiO2)

Chalcedony

Chalcedony (SiO₂)

Pink Granite

Phaneritic Felsic Igneous Rock (composed primarily of K-Feldspar, Quartz, and Plagioclase)

Pyrite

Iron Sulfide (FeS2)

Moonstone

Adularia (orthoclase) or Albite (plagioclase), a potassium aluminum silicate of the feldspar group

Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Quartz (Milky/Common)

Silicon Dioxide (SiO2)

Garnet-Mica Schist

Garnetiferous Porphyroblastic Schist

Sandstone (Pebble/Cobble)

Sandstone (arenite is a more precise term for sandstone with less than 15% matrix; this specimen appears to be a lithic or quartz arenite)

Pyrite (Fool's Gold)

Iron Disulfide (FeS2)

Blue Chalcedony and Picture Jasper Beads

Blue Chalcedony (SiO2), Picture Jasper (SiO2)

Basalt with Amygdules

Amygdaloidal Basalt

Amygdaloidal Basalt

Basalt with secondary mineral infilling

Moqui Marble (Shaman Stone)

Ironstone Concretion (Fe2O3 with a sandstone core)

Piddock-bored Mudstone

Lutite (Siltstone or Mudstone) with Pholad borings

Mica Schist (Garnetiferous)

Garnet-Mica Schist

Granitic Quartz with Feldspar

Granite (composed primarily of SiO2 and KAlSi3O8)

Fossilized Gastropod (Snail)

Class Gastropoda (internal mold or 'steinkern')

Petrified Wood

Silicified Wood (SiO2)

Orbicular Granite

Orbicular Granidiorite / Plutonic Igneous Rock

Petrified Wood

Silicified wood (primarily Silicon Dioxide, SiO2)

Aragonite Star Cluster

Aragonite (Calcium Carbonate, CaCO3)

Chert (Iron-stained)

Microcrystalline Quartz (SiO2)

Ammonite Fossil

Ammonoidea (subclass)

Pink Granite

Phaneritic Quartz-Feldspar Granite

Moqui Marble (Concretion)

Iron Oxide Concretion (Hematite-cemented Sandstone)