Igneous, Sedimentary, And Metamorphic

Natural freshwater pearls

Pearl (nacreous calcium carbonate; chiefly aragonite, CaCO₃)

Milky quartz crystal cluster

Quartz (silicon dioxide, SiO₂)

Tumbled milky quartz

Quartz (silicon dioxide, SiO₂)

Milky quartz

Quartz (silicon dioxide, SiO₂)

Yellow chalcedony or quartz fragment

Microcrystalline quartz, SiO₂ (tentative; possibly iron-stained chalcedony)

Polished fossil coral

Fossilized coral, commonly agatized coral (silica replacing CaCO₃)

Silicified oyster fossil

Fossil oyster shell, commonly Ostrea or Crassostrea, replaced or encrusted by chalcedony/quartz

Quartz geode or quartz-bearing rock

Quartz (SiO₂), likely in a chalcedony- or basalt-hosted cavity

Honey-colored quartz cluster

Quartz, silicon dioxide (SiO₂), likely iron-stained or included quartz

Milky quartz-bearing rock, possibly quartzite

Quartz (SiO₂), likely in a quartzite or quartz-rich vein

Fossilized bone fragment (probable mammalian tooth or bone)

Mineralized bone, commonly hydroxyapatite [Ca5(PO4)3(OH)] replaced or impregnated by silica/calcite

Yellow-orange quartz/chalcedony pebble (possibly citrine-bearing)

Quartz, SiO₂; likely microcrystalline chalcedony with iron staining

Baked-clay ceramic fragment (likely brick or pottery)

Fired clay, primarily aluminosilicate minerals; not a natural rock

Weathered quartz-bearing rock, possibly calcite vein fragment

Indeterminate; likely quartz (SiO₂) with carbonate minerals such as calcite (CaCO₃)

Amethyst and mixed gemstone bracelet

Amethyst: purple quartz, silicon dioxide (SiO₂); likely accompanied by other quartz or decorative mineral beads

Oyster shell fragment

Ostreidae shell; primarily calcite (CaCO₃)

River Pebbles and Quartz

Mixed Igneous, Sedimentary, and Metamorphic Rocks (Silicon Dioxide SiO2 dominant)

Agate

SiO2 (Chalcedony/Quartz)

Clear Quartz

Silicon Dioxide (SiO2)

Zoisite with Rubellite (Ruby in Zoisite)

Zoisite with inclusions of Hornblende (Anyolite)

Clear Quartz

Silicon dioxide (SiO2)

Chalcopyrite

Copper Iron Sulfide (CuFeS2)

Agate

Silicon Dioxide (Chalcedony), SiO2

Gravel / Small Pebble

Rock Fragment (Gravel)

Agate

Chalcedony (SiO2)

Gravel (Crushed Stone Aggregates)

Mixed Siliciclastic / Carbonate Aggregate

Mixed Tumbled Rocks and Minerals Collection

Mixed Minerals and Rocks (Quartz, Feldspar, Jasper, Agate, Lapis Lazuli, Sodalite, Rose Quartz, Fluorite, etc.)

Zoisite with Ruby (Anyolite)

Zoisite – Ca2Al3(SiO4)3(OH) with inclusions of Ruby (Al2O3:Cr)

Zoisite with Hornblende

Zoisite (Ca2Al3(SiO4)3(OH)) with Amphibole inclusions

Blue Apatite

Fluorapatite (Ca5(PO4)3F)

Mossy Rock

Mixed lithology rock with Bryophyta (moss)

Quartz

Silicon Dioxide (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Quartz

Silicon Dioxide (SiO2)

White Agate / Chalcedony

Silicon Dioxide (SiO2)

Unidentified gray-brown stone

Likely fine-grained quartz–feldspar rock; exact identification is not possible from this close, blurred image

Unidentifiable Rock Fragment

Pyrite

Iron Sulfide (FeS2)

Pyrite in Quartz

Iron Sulfide (FeS2) on Silicon Dioxide (SiO2)

Quartz (Milky Quartz / Quartzite)

Silicon Dioxide (SiO2)

Quartz (Milky/Clear variety)

Silicon Dioxide (SiO2)

Clear Quartz

Silicon Dioxide (SiO2)