Igneous And Mineral

Milky quartz cluster

Quartz (silicon dioxide, SiO₂)

Milky quartz crystal cluster

Quartz (silicon dioxide, SiO₂)

Quartz and Mixed Minerals

Silicon Dioxide (SiO2)

Limonite

FeO(OH)•nH2O

Limonite

FeO(OH)•nH2O

Unidentified polished mineral specimen

Indeterminate; likely a pale feldspar or quartz-bearing material

Feldspar

Feldspar Group (Tectosilicate, e.g., KAlSi3O8)

Quartz

Silicon Dioxide (SiO2)

K-Feldspar

Potassium Feldspar (KAlSi3O8)

Limonite

FeO(OH)•nH2O

Limonite

FeO(OH)·nH2O

Muscovite Mica

Muscovite (KAl2(AlSi3O10)(OH)2)

Quartz

Silicon Dioxide (SiO2)

Calcite

Calcium Carbonate (CaCO3)

Pegmatite

Igneous Pegmatite

Chalcopyrite

Copper Iron Sulfide (CuFeS2)

Blue Apatite

Calcium phosphate fluorapatite, Ca5(PO4)3(F,Cl,OH)

Magnetite

Magnetite (Fe3O4)

Granite

Felsic intrusive igneous rock

Blue Apatite

Fluorapatite (Ca5(PO4)3F)

Granite

Intrusive Igneous Rock

Clear Quartz

SiO2 (Silicon Dioxide)

Polished dark stone sphere, likely black obsidian

Obsidian (natural volcanic glass; composition varies, commonly rhyolitic)

Mica-rich granite (likely weathered pegmatitic granite)

Granite, chiefly quartz (SiO₂), feldspar, and mica (muscovite and/or biotite)

Quartz

Silicon Dioxide (SiO2)

Blue Apatite

Apatite (Ca5(PO4)3(F,Cl,OH))

Granite and Basalt Specimen

Plutonic and Volcanic Igneous Rocks

Prehnite

Prehnite (Ca2Al(AlSi3O10)(OH)2)

Prehnite

Prehnite (Ca2Al2Si3O10(OH)2)

Galena

Lead Sulfide (PbS)

Limonite

FeO(OH)·nH2O

Limonite Concretion

Hydrated Iron Oxide Hydroxide, FeO(OH)nH2O

Pegmatite

Igneous Pegmatite

Pegmatite

Igneous Pegmatite

Feldspar

Feldspar Group (Tectosilicate, e.g., KAlSi3O8)

Magnetite / Hematite mix (Iron Ore)

Fe3O4 (Magnetite) / Fe2O3 (Hematite)

Topaz

Al2SiO4(F,OH)2

Copper Ore

Mixed copper sulfides/oxides in gangue matrix

Magnetite

Magnetite (Fe3O4)

Labradorite

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

Limonite

FeO(OH)•nH2O

Limonite

FeO(OH)•nH2O