Mineraloid (Human Made Geological Specimen)

Granite

Phaneritic Felsic Igneous Rock

Sandstone

Arenite (SiO2 based with various mineral cements)

White Quartz Pebble (Milky Quartz)

Silicon Dioxide (SiO2)

Quartz / Quartzite

Silicon Dioxide (SiO2)

Ferruginous Sandstone

Clastic Sedimentary Rock (Iron-rich)

Pyrite (on the right) and Magnetite or Hematite (on the left)

Iron Sulfide (FeS2) and Iron Oxide (Fe3O4 or Fe2O3)

Sandstone (with possibly iron oxides and other minerals)

Sandstone

Geode with Quartz and possibly Jasper/Hematite

Quartz (SiO2) and Chalcedony (cryptocrystalline SiO2), possibly stained by iron oxides

Basalt

Extrusive Mafic Igneous Rock (composed primarily of Plagioclase, Pyroxene, and Olivine)

Pyrite

Iron Sulfide (FeS2)

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Quartz (Milky or White Quartz)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Quartzite with Chert inclusions

Metamorphosed Quartz-rich Rock (SiO2)

Fossiliferous Limestone

Calcite (CaCO3) with Bioclastic inclusions

Quartzite

Quartzite (primarily SiO2)

Amygdaloidal Basalt

Amygdaloidal Basalt (extrusive volcanic rock with secondary mineral infilling)

Granite with Biotite and Quartz

Phaneritic Felsic Igneous Rock (composed of SiO2, KAlSi3O8, and K(Mg,Fe)3AlSi3O10(OH)2)

Moqui Marble (Iron-Oxide Concretion)

Iron Oxide Concretion (Fe2O3)

Sandstone or Limestone

Sedimentary Rock

Ironstone Concretion (Moqui Marble)

Iron-oxide Concretion (Hydrated ferric oxide, Fe2O3·nH2O)

Olivine in Basalt (Peridotite Xenolith)

Forsterite-rich Olivine (Mg2SiO4) in Aphanitic Basalt

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Obsidian

Volcanic Glass (SiO2 rich)

Feldspar

KAlSi3O8 - NaAlSi3O8 - CaAl2Si2O8

Pyrite

Iron Sulfide (FeS2)

Rhyolitic Tuff (Breccia Type)

Rhyolitic Pyroclastic Rock (Mixed Silicates including Quartz, Feldspar, and Volcanic Glass)

Sandstone

Arenite (primarily SiO2 with various cementing agents)

Granite

Phaneritic Igneous Rock (composed of quartz, alkali feldspar, and plagioclase)

Ferruginous Sandstone

Arenite with Iron-Oxide Cement (SiO2 with Fe2O3/FeO(OH))

Vesicular Basalt (Amygdaloidal)

Vesicular Basalt (Fe-Mg rich extrusive volcanic rock)

Basalt with Olivine Phenocrysts

Porphyritic Basalt (with (Mg, Fe)2SiO4)

Quartzite with Quartz Veining

Quartzite (primarily SiO2)

Vesicular Basalt

Aphanitic Mafic Igneous Rock (with Vesicular Texture)

Quartzite with Garnet

Garnetiferous Quartzite (SiO2 + X3Y2(SiO4)3)

Green Onyx (Banded Calcite)

Calcite (Calcium Carbonate, CaCO3)

Granitic Pegmatite

Granitic Pegmatite (principally Quartz, Potassium Feldspar, and Mica)

Mica Schist

Mica Schist (primarily Muscovite and Quartz)

Schist

Mica Schist (primarily consisting of muscovite, biotite, and quartz)

Sedimentary Breccia

Clastic Breccia (CaCO3/SiO2 matrix)

Banded Gneiss

Gneiss (High-grade Regional Metamorphic Rock)

Ventifact

Eolian Ventifact (often composed of basalt, chert, or quartzite)