Synthetic (Not A Rock Or Mineral)

Sandstone

Arenite (SiO2 based)

Sandstone

Arenite

Granite (weathered, possibly porphyritic)

Granite; primarily quartz (SiO₂), feldspars, and mica/amphibole

Amygdaloidal Basalt

Amygdaloidal Basalt (Mafic volcanic rock)

Quartz with Mica

Silicon Dioxide (SiO2) with Mica group inclusions

Ironstone Concretion (Moqui Marble / Boji Stone)

Sedimentary Iron Oxide Concretion (Fe2O3 / FeO(OH))

Agate (Common Chalcedony)

Silicon Dioxide (SiO2)

Quartz Vein in Host Rock

Silicon Dioxide (SiO2) within metamorphic/igneous matrix

Slate with Quartz Vein

Foliated Metamorphic Rock (Mainly Quartz, Muscovite, Chlorite)

Quartz (Druzy on Matrix)

Silicon Dioxide (SiO2)

Polished greenstone pebble

Likely serpentinite or chlorite-rich greenschist

Titanium-coated Metal Cube (Man-made Fidget Toy)

Titanium-anodized or electroplated alloy (e.g., Ti-coated Zinc or Aluminum)

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Quartz vein in weathered host rock

Quartz (SiO₂), likely in a weathered metamorphic or igneous matrix

Iron-stained brown mineral/rock fragment

Most likely limonite/goethite-rich material (hydrated iron oxides), possibly weathered ironstone; exact identification requires testing

Banded gneiss

Foliated gneiss, likely quartz–feldspar–mica gneiss

Vesicular Basalt (or Scoraceous Basalt)

Basalt (Vesicular texture)

Granite Pebbles

Granite (composed primarily of Quartz SiO2, Feldspar (KAlSi3O8 – NaAlSi3O8 – CaAl2Si2O8), and Mica)

Greywacke (likely)

Greywacke (a type of sandstone)

Sandstone Pebble

Sandstone (Silicon dioxide-rich clastic sedimentary rock)

Sandstone Cobble with Iron Staining

Arenite with Limonite/Hematite staining

Serpentine Sphere

Serpentinite

Rounded gray river pebble, likely basalt or andesite

Fine-grained mafic to intermediate volcanic rock; commonly basalt (plagioclase ± pyroxene/olivine)

Shale or Slate with Quartz Veins

Shale (fine-grained clastic sedimentary rock) or Slate (low-grade metamorphic rock formed from shale) with Quartz (SiO2) veins

Druzy Quartz on Chalcedony Matrix

Silicon Dioxide (SiO2)

Speckled feldspar-rich pebble

Likely leucocratic granite or granitic pegmatite, chiefly potassium feldspar with dark biotite or amphibole

Small dark mineral or rock fragment

Undetermined; possibly a dark mafic mineral such as biotite or magnetite

Weathered golden-brown mineral/rock fragment

Indeterminate from image; possibly iron-stained quartz, feldspar, or a sulfide-bearing rock

Unidentified brown mineral/rock fragment

Indeterminate from image; possibly iron-stained quartz, feldspar, or weathered limonite

Sandstone (Ferruginous)

Sandstone (primarily SiO2 with iron oxide Fe2O3 staining)

Sandstone

Clastic sedimentary rock

Magnetic Hematite

Magnetized Hematite (an iron oxide mineral, Fe2O3, that has undergone magnetization)

Quartz–iron-oxide breccia or weathered quartz-bearing rock

Quartz (SiO₂) with limonite/goethite and possibly iron sulfides in a brecciated host

Green Aventurine

Silicon Dioxide (SiO2) with inclusions of Fuchsite (K(Al,Cr)2(AlSi3O10)(OH)2)

Polished moss agate (likely)

Chalcedony, microcrystalline SiO₂, with included green minerals such as chlorite or hornblende

Sandstone (lithic wacke)

Arenite / Lithic Wacke (mostly SiO2 with rock fragments)

Sandstone (likely Greywacke or Lithic Sandstone)

Arenite / Wacke

Pink granite (likely weathered granite)

Granite, composed mainly of quartz, feldspar, and mica

Mixed Rock Collection (Pebbles and Stones)

Various geological specimens

Quartz Vein in Basalt or Porphyry

Silicate-veined volcanic rock

Quartz-Veined Gneiss or Metamorphic Rock with Quartz Veins

Quartz-veined metamorphic rock (Silicate mineral assemblage)

Quartz River Pebble

Silicon Dioxide (SiO2)