Not A Rock Or Mineral

Ferruginous Siltstone or Mudstone

Ferruginous Siltstone / Goethitic Sandstone

Granite

Phaneritic Igneous Rock (Granite)

Quartz (River Pebble)

Silicon Dioxide (SiO2)

Moldavite

Moldavite (Siliceous vitreous substance)

Basalt with inclusion

Basalt (Aphanitic-Porphyritic texture)

Amethyst

Amethyst (Silicon Dioxide with iron impurities), SiO2

Quartz (in a rock matrix)

Quartz (SiO2)

Concretion or Geode (unbroken)

Varied (depending on mineral composition and cementing agent). For quartz-lined geodes, the scientific name of the dominant mineral would be Quartz (SiO2). For calcite-lined geodes, Calcite (CaCO3). Concretions are often composed of cryptocrystalline quartz (chert), calcite, or iron oxides.

Gneiss

High-grade foliated metamorphic rock

Mica Schist

Mica Schist (primarily Muscovite or Biotite KAl2(AlSi3O10)(OH)2)

White Agate (Chalcedony)

Silicon Dioxide (SiO2)

N/A - Man-made object (Jewelry Chain)

Antiqued or Oxidized Metal Chain (often Steel or Brass)

Milky Quartz

Silicon Dioxide (SiO2)

Quartz Druze on Matrix

Silicon Dioxide (SiO2)

Greenschist (Chlorite Schist)

Greenschist (Metamorphic rock dominated by chlorite, actinolite, and epidote)

Travertine

Terrestrial Sedimentary Rock (CaCO3)

Labradorite

Labradorite, (Ca, Na)(Al, Si)4O8

Garnet (almandine or pyrope variety)

Silicate mineral Group: (Fe, Mg, Mn, Ca)3(Al, Fe, Cr)2(SiO4)3

Amethyst Lace Agate / Banded Amethyst

Silicon Dioxide (SiO2) with Fe3+ impurities

Amethyst

Amethyst (Silicon Dioxide, SiO2 + Fe)

Prehnite

Prehnite, Ca2Al(AlSi3O10)(OH)2

Petrified Wood

Silicified Wood (primarily SiO2 - Silicon Dioxide)

Banded Agate (Onyx type)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Carnelian Agate

Carnelian (SiO2 with iron oxide impurities)

Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Shale or Argillite

Shale (fine-grained clastic sedimentary rock) or Argillite (low-grade metamorphic rock derived from shale)

Chalcedony

Silicon dioxide (SiO2) - Cryptocrystalline Quartz

Tree Agate

Dendritic Agate (Silicon Dioxide, SiO2)

Milky Quartz Pebble

Silicon Dioxide (SiO2)

Quartz (Milky or Clear variety)

Silicon Dioxide (SiO2)

Rose Quartz

Silicon Dioxide (SiO2) with trace amounts of titanium, iron, or manganese

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Milky Quartz

Quartz (Silicon Dioxide - SiO2)

Quartz with Iron Staining

Silicon Dioxide (SiO2)

Vesicular Basalt (Lava Rock)

Aphanitic Mafic Igneous Rock

Sandstone (likely Quartzose Sandstone pebble)

Arenite (primarily SiO2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Fuchsite on Quartz

Muscovite (KAl2(AlSi3O10)(OH)2) with Chromium impurities

Basalt with Olivine Phenocrysts

Porphyritic Basalt (containing Mg2SiO4 - Fe2SiO4)

Basalt

Basalt (Aphanitic Mafic Igneous Rock)