Sedimentary Or Igneous (Secondary Formation)

Small white crystalline mineral fragment

Indeterminate; possibly calcite or quartz

Pyrite

Iron Sulfide (FeS2)

Peacock Ore (Bornite or Iridescent Chalcopyrite)

Bornite (Cu5FeS4) or Chalcopyrite (CuFeS2) with oxidation

Ferruginous Quartz

Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3) inclusions

Stichtite in Serpentine (Atlantasite)

Mg6Cr2CO3(OH)16·4H2O (Stichtite) within Mg3Si2O5(OH)4 (Serpentine)

Tumbled dark metallic mineral specimen

Likely hematite or magnetite; identification is uncertain from the photograph

Hematite

Iron (III) oxide (Fe2O3)

Magnetite / Iron Ore (likely Hematite-Magnetite mix)

Magnetite (Fe3O4)

Hematite

Iron(III) oxide (Fe2O3)

Clear Quartz

Silicon Dioxide (SiO2)

Quartz vein in weathered host rock

Milky quartz (SiO₂), likely in a feldspathic or carbonate-rich matrix

Potassium Feldspar

Orthoclase (KAlSi3O8)

White Agate (Chalcedony)

Silicon Dioxide (SiO2)

Amethyst

Amethyst (Silicon Dioxide - SiO2 with iron impurities)

Quartz pebble

Silicon Dioxide (SiO2)

Conglomerate Pebble (with Chert / Quartz)

Sedimentary Conglomerate / Breccia Pebble

Quartz

Silicon Dioxide (SiO2)

Quartz

Silicon Dioxide (SiO2)

Limonite / Goethite Ironstone Concretion

FeO(OH)·nH2O (Hydrated Iron Oxide)

Quartz

Silicon Dioxide (SiO2)

Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Carnelian

Carnelian (Chalcedony - SiO2)

Sandstone (Quartzite texture)

Arenite (SiO2 secondary)

Magnetite

Magnetite (Fe3O4)

Weathered sandstone or iron-stained sedimentary rock

Quartz-rich sandstone, likely ferruginous sandstone (SiO₂-dominated)

Weathered iron-rich stone, likely basalt or ironstone

Indeterminate; possibly vesicular basalt (plagioclase–pyroxene) or ferruginous sandstone/ironstone

River Stone (Chalcedony/Jasper variety)

Microcrystalline Quartz (SiO2)

Prehnite

Prehnite (Ca2Al2Si3O10(OH)2)

Quartz Pebble

Quartz (SiO2)

Biotite-bearing metamorphic rock, likely schist

Mica schist; chiefly quartz, feldspar, and biotite mica

Likely banded ironstone (possibly a polished or naturally smoothed piece)

Iron-rich chert/jasper with iron oxides; exact identification is uncertain from the small, indirect image

Quartz-rich feldspathic rock, possibly granite or arkose

Granite-like aggregate of quartz (SiO₂), feldspar, and minor iron oxides

Red Hematite (Banded Iron Formation)

Hematite (Fe2O3)

Red Quartz (Carnelian/Red Jasper Agate)

Silicon Dioxide (SiO2) with Iron Oxide inclusions

Pink granite (weathered fragment)

Granite, primarily quartz–feldspar–mica (pink alkali feldspar, plagioclase, quartz, biotite/hornblende)

Quartz Crystal Cluster

Silicon Dioxide (SiO2)

Jasper with Purple Fluorite or Chalcedony

Silicon Dioxide (SiO2) with mineral inclusions

Amygdaloidal Basalt

Vesicular-Amygdaloidal Basalt (Mafic Extrusive)

Tumbled dark metallic mineral specimen, possibly hematite or magnetite

Hematite (Fe₂O₃) or magnetite (Fe₃O₄); visual identification is uncertain

Hematite

Iron(III) oxide (Fe2O3)

Quartz (Milky/Common)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)