Mineral With Artificial Coating

Yellow Quartz (possibly dyed)

Silicon Dioxide (SiO2)

Sandstone (Red Sandstone)

Arenite (SiO2 based with Fe2O3 staining)

Vesicular basalt (likely weathered volcanic rock)

Basalt; primarily plagioclase feldspar, pyroxene, and commonly olivine

Ferruginous Quartz

Silicon Dioxide (SiO2) with iron oxide inclusions (Limonite/Goethite)

Polished brown flint/chert (likely)

Microcrystalline quartz, SiO₂ (chalcedonic flint/chert)

Rainbow Hematite (Titanium-Coated Hematite)

Titanium-treated Hematite (Fe2O3)

Polished red jasper

Jasper, an opaque microcrystalline variety of quartz (SiO₂), colored mainly by iron oxides

Malachite (possibly chrysocolla-bearing)

Malachite, Cu₂CO₃(OH)₂; the blue-green areas may include chrysocolla, Cu₂H₂Si₂O₅(OH)₄

Peacock ore (bornite/chalcopyrite), likely treated

Bornite, Cu₅FeS₄, and/or chalcopyrite, CuFeS₂

Quartz (Iron-Stained)

Silicon Dioxide (SiO2)

Quartz geode/drusy quartz cluster

Quartz (SiO₂), with probable feldspar host and minor iron-oxide staining

Ferruginous Quartz

Quartz (Silicon Dioxide, SiO2) with iron oxide inclusions

Limonite / Ironstone

Hydrated Iron Oxide (FeO(OH)·nH2O)

Polished porphyritic volcanic pebble

Likely porphyritic basalt or andesite; exact identification requires a fresh surface and mineral tests

Titanium Coated Quartz (Aura Quartz)

Silicon dioxide with titanium vapor deposition (SiO2)

Quartz with Iron Oxide Monzonite or Sandstone contact

Quartz (SiO2) with Limonite/Hematite staining

Rounded granitic gneiss or granite cobble

Biotite granite, possibly weakly foliated granitic gneiss; quartz–feldspar–biotite assemblage

Yellow Chalcedony (Tumbled/Cabochon)

Silicon dioxide (SiO2)

Ferruginous Quartz

Silicon Dioxide (SiO2) with Hematite/Limonite impurities

Citrine Quartz / Yellow Quartz Pebbles

Silicon Dioxide (SiO2)

Green Banded Agate

Agate (Variety of Chalcedony/Quartz), SiO2

Red Sandstone Pebble

Sedimentary quartz sandstone

Smelter Slag

Anthropogenic Silicate Slag

Bornite (Peacock Ore)

Bornite (Cu5FeS4)

Weathered quartz-rich rock, possibly granite or quartzite

Indeterminate; likely quartz–feldspar aggregate, potentially granitic or quartzitic material

Native Copper (Tumbled Nugget)

Cu (Native Element)

Vesicular basalt

Basalt, a mafic volcanic rock composed mainly of plagioclase feldspar, pyroxene, and often olivine

Red Quartz (Iron-stained Quartz)

Silicon Dioxide (SiO2) with Hematite/Iron Oxide inclusions

Quartz vein specimen, likely milky quartz with iron-stained host rock

Quartz (SiO₂), possibly with chalcedony and sulfide/oxide-bearing matrix

Iron-stained Quartz Pebble

Silicon Dioxide (SiO2) with Hematite/Limonite coatings

Quartz Vein (Iron-stained)

Silicon Dioxide (SiO2) with limonite/hematite staining

Quartz-rich mineral specimen, possibly druzy quartz with iron staining

Quartz (SiO₂), possibly coating a vesicular host rock

Yellow-green aventurine or serpentine pendant

Most likely serpentine-group mineral (magnesium silicate), possibly quartz-rich aventurine

Milky quartz vein rock

Quartz, SiO₂; likely massive vein quartz with iron-oxide staining

Iron-rich metamorphic rock (probable garnet-bearing schist or quartzite)

Garnet–quartz–mica schist/quartzite; composition likely quartz (SiO₂), iron oxides/hydroxides, mica, and possible almandine garnet

Quartz Geodes and Crystal Clusters

Silicon Dioxide (SiO2)

Dyed Agate

Silicon Dioxide (SiO2)

Polished vesicular basalt (likely iron-rich volcanic rock)

Basalt, predominantly plagioclase–pyroxene–olivine; surface may include iron-oxide minerals or metallic-looking infill

Likely tumbled brown stone

Indeterminate; possibly jasper, chert, or iron-stained quartzite

Red Sandstone

Arenite with Hematite (Fe2O3)

Tumbled milky chalcedony (likely common opalite-like quartz)

Chalcedony, microcrystalline SiO₂; possibly pale common opal, hydrated SiO₂·nH₂O

Carnelian

Carnelian (Silicon Dioxide - SiO2 with Hematite impurities)