Man Made Material, Not A Natural Rock Or Mineral Specimen

Diamond

Diamond (C)

Raw Citrine

Citrine (Silicon Dioxide, SiO2)

Weathered granite-like rock

Coarse-grained granitic rock, likely quartz–feldspar–mica aggregate

Diamond

Native Carbon (C)

Mystic Topaz

Aluminum silicate fluoride hydroxide with titanium coating (Al2SiO4(F,OH)2)

Amethyst-bearing quartz cluster

Quartz, SiO₂; purple coloration from irradiation and trace iron

Milky Quartz with Iron Inclusions

Silicon Dioxide (SiO2) with Hematite/Limonite

Tumbled quartz pebble

Quartz (SiO₂), likely milky or fractured rock crystal

Clear quartz crystal point

Quartz (silicon dioxide, SiO₂), likely a polished or cut crystal

Garnet-bearing gneiss

Quartz–feldspar–mica gneiss with iron-rich garnet (commonly almandine)

Dyed Pink Agate Slice

Silicon Dioxide (SiO2) - Chalcedony variety Agate

Marble

Recrystallized Calcite (CaCO3)

Malachite

Malachite (Cu2CO3(OH)2)

Amethyst on Basalt Matrix

Crystalline Silicon Dioxide (SiO2) with iron impurities

Honey Calcite

Calcite (Calcium Carbonate, CaCO3)

Sandstone (Ferruginous)

Arenite with Iron Oxide cement

Quartz-rich breccia or altered granite fragment

Polymineralic quartz–feldspar rock, likely hydrothermally altered granite/pegmatite

Chert (Grey-Green Flint)

Microcrystalline silicon dioxide (SiO2)

Weathered granite (likely biotite granite)

Granite; interlocking quartz, feldspar, and mica, commonly with biotite

Limestone (Grey and White specimens)

Calcium Carbonate (CaCO3)

Tumbled serpentine with dark magnetite/chromite matrix

Serpentinite; chiefly antigorite/lizardite, Mg3Si2O5(OH)4, with magnetite and possibly chromite

Quartzite (Ferruginous Quartz)

Silicon Dioxide (SiO2) with Iron Oxide inclusions

Botryoidal Malachite

Malachite - Cu2CO3(OH)2

Serpentinite (likely)

Serpentinite, dominated by serpentine-group minerals (antigorite, lizardite, or chrysotile)

Quartz–feldspar–mica metamorphic rock, likely gneiss

Gneiss; composition commonly quartz (SiO₂), feldspars, biotite/hornblende, and minor accessory minerals

Sandstone (Ferruginous)

Arenite (primarily SiO2 with Fe2O3 staining)

Rounded gray-brown cobble, likely weathered sandstone or quartzite

Tentatively quartz-rich sandstone (SiO₂-dominated); exact identification requires hardness and acid tests

Blue Topaz

Al2SiO4(F,OH)2

Sandstone

Sedimentary Clastic Rock (Quartz Arenite)

Citrine Quartz / Yellow Quartz Pebbles

Silicon Dioxide (SiO2)

Dzi Bead Necklace (Agate/Carnelian)

Chalcedony (cryptocrystalline Quartz), SiO2

Coquina

Coquina (Bioclastic Limestone)

Petrified Wood

Silicified Wood (primarily SiO2)

Weathered sandstone or limestone fragment

Likely quartz-rich sandstone or micritic limestone; exact identification requires testing

Tumbled blue-dyed stone, likely basalt or blue aventurine

Likely fine-grained basalt (plagioclase and pyroxene), possibly coated or dyed; exact identification requires testing

Rounded sandstone pebble

Quartz-rich sandstone (likely arkosic or lithic sandstone)

Banded Iron Formation (Fragment)

Banded Iron Formation (BIF)

Basalt

Basalt (extrusive volcanic rock)

Red Slag Glass (Cullet)

Amorphous Silicon Dioxide (SiO2) with metallic dopants

Yellow Quartz

Silicon Dioxide (SiO2)

Red Sandstone

Arenite (SiO2 with Fe2O3)

Diamond

Carbon (C)