Man Made Material, Not A Natural Rock Or Mineral Specimen

Ironstone Concretion / Goethite-Hematite Nodule

Goethite/Hematite (α-FeO(OH) / Fe2O3)

Dumortierite in Quartz

Dumortierite (Al6O3(BO3)(SiO4)3) with Quartz (SiO2)

Sandstone (Quartzose)

Arenite (primarily SiO2)

Likely tumbled dark volcanic rock

Probably basalt or basaltic andesite; exact identification is uncertain from the image

Yellow Quartz Pebble

Silicon Dioxide (SiO2)

Conglomerate

Conglomerate (clastic sedimentary rock)

Amethyst (with Pyrite and other minerals)

Silicon Dioxide (SiO2)

Chert

Microcrystalline quartz (SiO2)

Pink Granite

Phaneritic Felsic Intrusive Igneous Rock

Citrine (likely Heat-Treated Amethyst)

Silicon Dioxide (SiO2)

Limonite (Yellow Ochre)

FeO(OH)·nH2O (Hydrous iron(III) oxide-hydroxide mixture)

Smooth river pebble

Indeterminate lithology; likely fine-grained quartz-rich sandstone, siltstone, or weathered chert

Quartz geode (likely amethyst-bearing)

Silica geode; quartz, SiO₂, with possible amethyst and minor iron oxides

Dendritic Agate (Tree Agate)

Chalcedony (Silicon Dioxide, SiO2) with Manganese or Iron Oxide inclusions

Granodiorite

Phaneritic Plutonic Intermediate-Felsic Rock

Polished porphyritic basalt (likely)

Basalt, a fine-grained mafic volcanic rock; visible inclusions may be olivine, feldspar, or vesicle infillings

Granite

Granite

Red jasper in gray host rock (likely hematite-stained quartzite or rhyolite)

Jasper: microcrystalline quartz (SiO₂), with iron-oxide coloration; exact host uncertain from image

Moldavite

Tektite (Silicates with aluminum, iron, manganese, and potassium oxide glass)

Tree Agate (or Moss Agate)

Dendritic Agate (Silicon Dioxide - SiO2)

Planet Earth

Gaia (Silicate Terrestrial Planet)

Tumbled blue stone, likely blue aventurine or dyed quartz

Quartz (SiO₂), possibly with fuchsite inclusions; exact identification requires testing

White quartz in dark matrix (likely quartz-bearing breccia or polished composite specimen)

Quartz, SiO₂, in an unidentified dark silicate matrix

Limonite Nugget

Limonite (Hydrated iron oxide-hydroxide, FeO(OH)·nH2O)

Citrine

Silicon dioxide (SiO2)

Diorite

Intermediate plutonic igneous rock

Rounded beach pebble

Lithology indeterminate; likely fine-grained sandstone, mudstone, or weathered volcanic rock

Sandstone (Ferruginous)

Arenite with Iron Oxide staining (Fe2O3)

Dyed Agate

Agate (SiO2)

Citrine Quartz

Citrine (Silicon Dioxide - SiO2)

Sandstone (Weathered Coastal Boulder)

Arenite (composed primarily of SiO2)

Small rounded stone, likely basalt or weathered mafic rock

Fine-grained basalt; exact identification requires testing

Peacock ore (iridescent chalcopyrite, possibly bornite)

Chalcopyrite, CuFeS₂; the iridescent surface may be natural tarnish or artificial acid treatment. Similar material is bornite, Cu₅FeS₄.

Quartz Druzy

Crystalline Silicon Dioxide (SiO2)

Granite

Granite (Felsic Plutonic Rock)

Milky Quartz/Clear Quartz Cluster

Silicon Dioxide (SiO2)

Sandstone

Sandstone (Quartzose/Feldspathic Sandstone)

Nacre (Mother of Pearl)

Nacre (Biogenic Aragonite/Calcite composite, CaCO3)

Unknown Tumbled Stone

Unknown (Too Blurry)

Quartz Pebble

Silicon Dioxide (SiO2)

Dyed Agate Geode

Silicon Dioxide (SiO2) with artificial pigment

Banded Sandstone (Liesegang Rings)

Arenite with Liesegang rings (SiO2/Fe2O3)