Organic Structure (Not A Rock)

Biological Bone (Patella/Knee)

Patella (part of the Human Skeletal System)

Red coral beads

Precious coral, commonly Corallium rubrum (calcium-carbonate skeleton)

Not a rock

Not a rock

Not a rock

Not a rock

Not a rock

Not a rock

Petoskey Stone

Hexagonaria percarinata (Fossilized Rugose Coral)

Polished operculum (“Shiva eye” shell)

Calcium-carbonate shell operculum, commonly from a turban snail (family Turbinidae); not a mineral specimen

River Rock

Sedimentary Rock (various compositions)

Polished ocean jasper

Microcrystalline quartz (SiO₂) with chalcedony, feldspar, and iron-oxide inclusions

Serpentinite

Serpentinite (a rock composed predominantly of serpentine group minerals)

Pink granite

Granite, chiefly quartz, potassium feldspar, and plagioclase with minor mica

Granite

Granite, a coarse-grained felsic intrusive igneous rock composed mainly of quartz, feldspar, and mica

Fossilized gastropod shell

Gastropoda indet.; shell originally composed mainly of aragonite (CaCO₃)

Red coral (coral beads)

Precious coral, usually Corallium spp.; composed primarily of calcium carbonate (calcite)

Pearls

Pearl: biomineralized aragonite (CaCO₃) and conchiolin

Weathered granite boulder

Granite, a coarse-grained felsic intrusive igneous rock, typically composed of quartz, feldspar, and mica

Tumbled granite pebble

Granite, a quartz–feldspar plutonic rock

Pearls

Aragonite (calcium carbonate) and Conchiolin

Pebble

Clast (specifically a granule or small pebble)

Shale

Shale (clastic sedimentary rock)

Clear gemstone earring (likely cubic zirconia)

Cubic zirconia (synthetic zirconium dioxide, ZrO₂); identification from the image is uncertain

Fossilized Bone in Matrix

Vertebrata fossil

Tumbled granite

Granite, a coarse-grained felsic intrusive igneous rock

Serpentinite

Serpentinite, a rock composed mainly of serpentine-group minerals (approximately Mg₃Si₂O₅(OH)₄)

Likely bituminous coal

Coal, predominantly carbon-rich organic matter; exact rank cannot be confirmed from the image

Not a geological specimen

N/A (man-made object)

Petrified Wood

Silicified wood (SiO2)

Stromatolite

Biogenic sedimentary rock / Calcium carbonate

Likely serpentinite

Serpentinite, composed mainly of serpentine-group minerals (e.g., antigorite, lizardite, or chrysotile)

Granite

Granite — a coarse-grained felsic intrusive igneous rock, typically composed of quartz, feldspar, and mica

Granite pebble

Granite, a coarse-grained felsic intrusive igneous rock composed mainly of quartz, feldspar, and mica

Turquoise (small irregular fragment)

Turquoise, hydrated copper aluminum phosphate: CuAl₆(PO₄)₄(OH)₈·4H₂O

Likely bituminous coal

Coal, predominantly carbon-rich organic matter; rank and composition cannot be confirmed from the image

Petrified Wood

Silicified wood (primarily quartz, SiO2)

Likely sodalite (rough blue specimen)

Sodalite, Na₈(Al₆Si₆O₂₄)Cl₂

Coal (Bituminous / Anthracite)

Organic Sedimentary Rock (Carbonaceous Rock)

Coal

Coal (Sedimentary Rock / Organic Rock)

Granite (likely weathered, coarse-grained specimen)

Granite; chiefly quartz, feldspar, and mica

Red jasper

Jasper, a microcrystalline variety of quartz (SiO₂), colored mainly by iron oxides

Tumbled jasper pebble

Jasper, an opaque microcrystalline variety of quartz (SiO₂), commonly colored by iron oxides and hydroxides

Petrified Wood

Fossilized Xylem (SiO2)

Sea Shell (Mollusk Shell)

Calcium Carbonate (Aragonite/Calcite)