Metamorphic (Man Made)

Quartz

Silicon Dioxide (SiO2)

Plagioclase Feldspar (specifically Albite/Oligoclase)

(Na,Ca)(Si,Al)4O8

Mica schist (possibly garnet–mica schist)

Muscovite–biotite schist; chiefly quartz, feldspar, muscovite, and biotite

Tumbled Clear Quartz

Silicon Dioxide (SiO2)

Marble

Metamorphosed Limestone (principally CaCO3)

Quartz

Quartz (SiO₂)

Ferruginous Sandstone (Ironstone)

Clastic Sedimentary Rock (composed of SiO2 with Fe2O3/FeO(OH) cement)

Sandstone (specifically Arkose or Quartz Arenite)

Arenite (primarily SiO2 with possible Feldspar)

Limestone

Calcareous sedimentary rock (CaCO3)

Red Jasper (Quartzite)

Silicon Dioxide (SiO2) with iron oxide inclusions

Citrine

Silicon Dioxide (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Quartz Crystal

Silicon Dioxide (SiO2)

Weathered iron-rich rock, possibly jasper or ironstone

Likely limonite/goethite-bearing siliceous rock; exact identification requires hardness and streak tests

Garnet

Garnet group species (likely Almandine, Fe3Al2(SiO4)3)

Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Red Sandstone

Arenite (with Iron Oxide / Hematite staining)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Quartz-rich rock, possibly milky quartz or quartzite

Quartz (silicon dioxide, SiO₂); if granular and foliated, likely quartzite

Quartz

Quartz (SiO2 - Silicon Dioxide)

Marble

Recrystallized Calcite (CaCO3)

Magnetite-rich iron ore (probable magnetite schist)

Magnetite (Fe₃O₄) in a foliated metamorphic matrix, possibly magnetite–biotite schist

Greenstone / Greenstone Pebble

Greenschist (metamorphosed basalt or gabbro)

Clear Quartz

Silicon Dioxide (SiO2)

Iron-rich quartzite or ferruginous metamorphic rock

Quartzite, predominantly SiO₂, stained by iron oxides (hematite/goethite)

Milky Quartz

Silicon Dioxide (SiO2)

White Marble

Recrystallized Calcite (CaCO3)

Milky Quartz

Quartz (Silicon Dioxide - SiO2)

Citrine

Silicon Dioxide (SiO2) with iron impurities

Mixed Quartz and River Pebbles (Stone Collection)

Mixed assortment containing mainly Silicon Dioxide (SiO2)

Citrine Quartz

Silicon Dioxide (SiO2) with ferric iron impurities

Iron-rich quartzite or ironstone fragment

Quartzite dominated by quartz (SiO₂), with iron oxides such as hematite/goethite

Pink Quartzite

Quartzite (principally Silicon Dioxide, SiO2)

Marble

Recrystallized Calcite (CaCO3) or Dolomite (CaMg(CO3)2)

Quartz Mineral

Silicon Dioxide (SiO2)

Dyed Blue Agate Slice

Silicon Dioxide (SiO2)

Weathered quartz-rich rock, possibly sandstone or quartzite

Likely quartzite (mostly SiO₂), though a granular sandstone is also possible

Greenstone

Greenschist / Meta-basalt

Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Weathered greenstone pebble

Metamorphosed mafic rock, commonly metabasalt or greenschist (exact identification requires testing)

Likely polished garnet fragment

Garnet group, possibly almandine (Fe₃Al₂Si₃O₁₂)

Feldspar

KAlSi3O8 - NaAlSi3O8 - CaAl2Si2O8