Not A Rock (Synthetic Material)

Brecciated Jasper

SiO2

Note: No specimen visible

Agate

Cryptocrystalline quartz, Chalcedony (SiO2)

Black rectangular gemstone pendant, likely obsidian or black glass imitation

Most plausibly black obsidian (volcanic glass; SiO₂-rich), though the image cannot exclude synthetic glass or black onyx

Cubic Zirconia (CZ) Jewelry

Zirconium dioxide (ZrO2)

Black Tourmaline

Schorl (Na(Fe²⁺)₃Al₆(OH)₄(BO₃)₃Si₆O₁₈)

Iron-stained rock fragment, possibly quartz-rich

Unidentified quartz-rich rock with iron-oxide staining (likely hematite/goethite)

Yellow Quartz Pebble

Silicon Dioxide (SiO2)

Metal Alloy (Likely Pewter or Sterling Silver)

Not a natural geological specimen; composed of refined metals. If pewter, it's a tin-based alloy. If sterling silver, it's 92.5% silver and 7.5% other metals (usually copper).

Jewelry Chain with Blue and Clear Gemstones (Likely Cubic Zirconia)

Cubic Zirconia (ZrO₂), Silver or White Gold/Platinum Alloy

Crushed Stone / Gravel

Aggregate (mixed lithology)

Tumbled serpentine with dark magnetite/chromite matrix

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

Pearl-embellished decorative cross

Pearl (biogenic calcium carbonate, predominantly aragonite) with rhinestone-mounted glass or synthetic gemstones

Sandstone or Limestone

Sedimentary Rock

Sandstone

Arenite

Rounded quartz-rich pebble

Lithic pebble; likely quartz/quartzite with iron-oxide staining

Rhinestone

Artificial Glass/Crystal

Rutilated Quartz

SiO2 with TiO2 inclusions (Rutile)

Shale (or Mudstone/Siltstone)

Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)

Quartz Vein in Siltstone

Silicon Dioxide (SiO2) within Sedimentary/Metamorphic Matrix

Blue glassy cabochon, likely blue quartz or synthetic glass

Possibly dyed blue chalcedony/quartz (SiO₂); visual identification is inconclusive

Vesicular basalt (likely scoriaceous basalt)

Mafic volcanic rock, chiefly plagioclase, pyroxene, and olivine; commonly iron-rich volcanic glass

Vesicular volcanic rock, likely scoria

Scoria; composition commonly basaltic to andesitic, rich in plagioclase and pyroxene

Blue opal heart cabochon

Common opal, hydrated amorphous silica (SiO₂·nH₂O), likely blue-dyed or synthetic opalite

Ruby in Fuchsite

Corundum (Al2O3) in Fuchsite (K(Al,Cr)3Si3O10(OH)2)

Weathered iron-rich rock, possibly limonite-bearing basalt or laterite

Indeterminate; likely Fe-oxide/hydroxide–altered mafic rock, dominated by limonite/goethite with silicate minerals

Shale (or Mudstone)

Laminose Mudrock (composition: clay minerals, quartz, and mica flakes)

Quartz Vein in Siltstone

SiO2 (Quartz) on clastic sedimentary matrix

River Rock

Sedimentary Rock (various compositions)

Mixed gravel and small stones

Unsorted gravel; individual clasts are not identifiable from the image

River-worn Chert

Microcrystalline Quartz (SiO2)

Sandstone

Clastic sedimentary rock (primarily SiO2)

Asphalt Pavement (with aggregate)

Asphalt concrete

White pebbles (rock material not identifiable from the image)

Undetermined; the smooth, pale pieces could be quartz, quartzite, or another light-colored rock

Vesicular Basalt (Scoria)

Vesicular Basalt

Quartz Vein in Sandstone

Quartz (SiO2) in Clastic Sedimentary Rock

Granite or Pegmatite in host rock

Granitoid / Felsic Intrusive Rock

Not a rock, mineral, or geological specimen

Red Sandstone

Arenite (SiO2 with Fe2O3)

Greenstone / altered mafic rock

Likely serpentinite or chlorite-rich metabasalt; exact identification requires testing

Pale greenish quartz-bearing rock, possibly serpentine or altered feldspar

Tentatively serpentinite-related rock (serpentine-group minerals) or altered granitic material; identification is uncertain from the photograph

Likely polished or naturally smoothed pebble with a pale mineral patch

Undetermined; possibly a dark volcanic rock with a quartz or feldspar inclusion