Sedimentary Or Mineral

Ironstone Pebble

Sedimentary Ironstone (Hematite/Limonite-bearing)

Weathered vesicular basalt (likely amygdaloidal basalt)

Basalt, composed mainly of plagioclase feldspar, pyroxene, and altered olivine; cavities may contain secondary zeolite, calcite, or silica

Banded gneiss

Gneiss, commonly quartz–feldspar–biotite gneiss

Vesicular basalt (possibly scoriaceous basalt)

Basalt, chiefly plagioclase feldspar, clinopyroxene, and iron-titanium oxides

Lazulite

Lazulite (MgAl2(PO4)2(OH)2)

Celestite

Celestine (SrSO4)

Pyrite

Iron Sulfide (FeS2)

Pyrite

Iron Sulfide (FeS2)

Celestite (Celestine)

Strontium sulfate (SrSO4)

Satin Spar (Selenite)

Gypsum (Calcium Sulfate Dihydrate) - CaSO4·2H2O

Magnetite

Magnetite (Fe3O4)

Quartz Geode

Silicon Dioxide (SiO2)

Quartz Geode

Silicon Dioxide (SiO2)

Quartz Geode

Silicon Dioxide (SiO2) within a geode

Quartz Geode

Crystalline Quartz (Silicon Dioxide, SiO2)

Red Jasper or Ironstone concretion

SiO2 or Fe2O3

Gypsum Wallboard (Drywall)

Hydrous calcium sulfate (CaSO4·2H2O)

Mixed rock and mineral specimen collection

Mostly undetermined from the photograph; apparent quartz-rich rocks, sandstone, granite/gneiss, and possibly iron-oxide-bearing specimens

Pyrite on Limestone

Iron Disulfide (FeS2) in Calcium Carbonate (CaCO3) matrix

Mixed river-worn rock and mineral collection

Mostly quartz/quartzite, feldspar-bearing granitoid, chert, and mafic volcanic rocks; exact species vary by pebble

Mixed rock and mineral collection

Mixed lithologies; likely quartz, feldspar, basalt, granite, chert, sandstone, and metamorphic rocks

Agate Geode

Chalcedony (SiO2 - Silicon Dioxide)

Herkimer Diamond in Matrix

Quartz (SiO2) in Dolostone (CaMg(CO3)2)

Jasper and Aquamarine (likely)

Jasper (Cryptocrystalline Quartz (SiO2)), Aquamarine (Beryl (Be3Al2Si6O18))

Jasper in Basalt Matrix

Silicon Dioxide (SiO2) with impurities; Chalcedony

Quartz Geode

Silicon Dioxide (SiO2)

Small red-brown mineral or rock fragment

Unidentified; possibly iron-oxide-rich jasper, garnet, or weathered sulfide

Unidentified brown rock fragment

Indeterminate from image; likely a weathered iron-rich lithic fragment

Mica-rich rock, likely mica schist

Mica schist, composed chiefly of muscovite and/or biotite with quartz and feldspar

Rounded metamorphic pebble, likely mica schist or gneiss

Mica schist/gneiss; commonly quartz, feldspar, and biotite or muscovite mica

Polished red gemstone pendant, likely red jasper or brecciated jasper

Jasper: microcrystalline quartz (SiO₂), commonly with hematite or iron-oxide inclusions

Likely weathered schist or gneiss fragment

Micaceous quartz-feldspar metamorphic rock; exact identification requires testing

Quartz heart (likely milky/included quartz)

Quartz, silicon dioxide (SiO₂)

Iron-Stained Quartzite

Recrystallized Meta-Quartzite (primarily SiO2)

Quartz Vein in Matrix (Breccia / Host Rock with Quartz)

Silicon Dioxide (SiO2) in Host Rock Matrix

Unidentified light-colored rock or mineral specimen

Indeterminate; possibly weathered calcite-rich material, limestone, or pale quartz-bearing rock

Beach Pebble (Quartzite / Sandstone)

Quartz-rich sedimentary or metamorphic rock pebble

Jasper

Silicon Dioxide (Microcrystalline Quartz, $SiO_2$)

Biotite-bearing metamorphic rock, likely schist

Mica schist; chiefly quartz, feldspar, and biotite mica

Banded Sandstone or Quartzite Pebble

SiO2 (dominant) with impurities

Likely raw mica-bearing metamorphic rock or mineral fragment

Tentatively biotite schist; visually similar dark mica-rich material

Quartz pebble

Silicon dioxide (SiO2)