This Is Not A Rock Or Mineral

Marine gastropod shell

Calcareous mollusk shell, primarily aragonite (CaCO₃), likely a whelk or conch

Pink Granite (Alkali-feldspar Granite)

Felsic intrusive igneous rock (composition: KAlSi3O8, SiO2, NaAlSi3O8)

N/A - Image does not contain a rock or mineral

Anthropogenic textile material

Pink granite

Granite, chiefly quartz–alkali feldspar–plagioclase with biotite/hornblende

Quartzite with Iron Staining

Metamorphic Quartz Sandstone

Tumbled Amethyst

Quartz (Silicon Dioxide, SiO2, colored by iron impurities)

Yellow Jasper

Microcrystalline Quartz (SiO2)

Pink Mimbres Agate / Plume Agate

Silicon dioxide (SiO2) with mineral inclusions

Jasper and Epidote in Quartzite

Metamorphic rock containing microcrystalline quartz, epidote, and jasper

Man-made Synthetic Material (Not a rock or mineral)

Polyester (Polyethylene terephthalate) / Faux Fur

Unknown Organic Object (likely a berry or fruit)

Not applicable; this is not a geological specimen. If it were a cranberry, its scientific name would be Vaccinium macrocarpon; if a cherry, it would be Prunus avium or Prunus cerasus.

Granite (likely weathered)

Granite, a quartz–feldspar–mica intrusive igneous rock

Graphic Granite (or Rapakivi-textured Granite)

Alkali feldspar granite

Granodiorite

Granodiorite (containing Quartz, Plagioclase Feldspar, Biotite, and Hornblende)

Jasper and Chalcedony Nodule

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Leopard Jasper

Microcrystalline Quartz (SiO2) with mineral inclusions

Quartz Geode

Silicon Dioxide (SiO2)

Dendritic Jasper

Silicon Dioxide (SiO2) with Manganese/Iron oxide inclusions

Rounded river pebble, likely granite or granitic gneiss

Granite-dominated felsic silicate rock; typically quartz, feldspar, and mica

Pink granite pebble

Granite, a coarse-grained felsic intrusive igneous rock

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2)

Amethyst

Amethyst (Silicon Dioxide - SiO2)

Agate Geode

Silicon Dioxide (Chalcedony/Quartz), SiO2

Granite-like felsic rock

Likely weathered granite or granitic gneiss; predominantly quartz, feldspar, and minor mica

Petrified Wood

Silicified Wood (SiO2)

Quartz Geode (Druzy Quartz)

Silicon Dioxide (SiO2)

Unidentified light-colored rock or mineral specimen

Indeterminate; possibly weathered calcite-rich material, limestone, or pale quartz-bearing rock

Grey River Stone (Gneiss/Schist mix)

Foliated Metamorphic Rock (variable mineral formula)

Tumbled granite

Granite, a coarse-grained felsic intrusive igneous rock

Weathered granite

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

Weathered granite

Granite, primarily quartz, alkali feldspar, plagioclase, and mica

Likely weathered granite or granitic gneiss fragment

Granite: quartz + feldspar + mica; possibly gneiss if foliation is confirmed

Druzy Quartz Geode (with Chalcedony)

Silicon Dioxide (SiO2)

Petrified Wood

Silicified Wood (SiO2)

Orbicular Gabbro

Orbicular Gabbro

Porphyry

Porphyritic Igneous Rock

Banded gneiss

Foliated gneiss, likely quartz–feldspar–biotite or amphibole gneiss

Ironstone (iron-oxide-rich rock)

Ferruginous sandstone or ironstone; likely composed chiefly of goethite and/or limonite, with quartz and clay

Unidentifiable Specimen

Undetermined

Gneiss

Quartz–feldspar–mica gneiss

Jasper and Quartz Breccia

Silicified Breccia / Microcrystalline Quartz

Uncertain fine-grained rock or mineral-bearing specimen

Indeterminate; possible quartz- or feldspar-bearing matrix with reflective grains