Mineral With Artificial Coating

Limonite-stained ironstone, possibly goethite

Goethite/limonite (FeO(OH) and hydrated iron oxides), identification tentative

Chrysocolla-rich copper ore

Chrysocolla (hydrated copper aluminosilicate), likely with malachite and limonite/goethite

Chalcopyrite (Peacock Ore)

Chalcopyrite (CuFeS2)

Weathered iron-rich stone, possibly limonite-bearing rock

Limonite/goethite mixture (hydrated iron oxides), identification uncertain from image

Turquoise

Turquoise (Hydrated phosphate of copper and aluminium), CuAl6(PO4)4(OH)8·4H2O

Iron-stained quartz vein rock

Quartz-rich vein material, predominantly silicon dioxide (SiO₂), with iron-oxide staining

Red Sandstone

Arenite (Ferruginous Sandstone)

Polished granite pebble

Granite; chiefly quartz, feldspar, and mica/amphibole

Limonite-stained Quartz

Silicon Dioxide with Iron Oxide Hydroxide, SiO2 + FeO(OH)*nH2O

Sandstone (Ferruginous)

Arenite (with Iron Oxide cement)

Sandstone (Red Sandstone)

Arenite (predominantly SiO2 with Fe2O3 cement)

Sandstone (Red)

Arenite (SiO2 with Fe2O3)

Limonite (Yellow Ochre)

Hydrated iron(III) oxide-hydroxide (FeO(OH)·nH2O)

Blue Obsidian (Cullet Glass)

Silicon Dioxide (Amorphous Glass)

Vesicular basalt (likely weathered scoria)

Basaltic scoria; predominantly calcium-rich plagioclase, clinopyroxene, and iron-magnesium oxides

Weathered granitoid rock

Granite or granitic gneiss; chiefly quartz, feldspar, and mica

Quartz-rich rock, likely milky quartz or quartzite

Quartz (SiO₂), possibly quartzite (recrystallized quartz sandstone)

Polished labradorite cabochon

Labradorite, CaAl₂Si₂O₈–NaAlSi₃O₈ (feldspar solid solution)

Red sandstone

Iron-oxide-cemented quartz-rich sandstone (ferruginous sandstone)

Quartz Druzy on Matrix

SiO2

Quartz Druzy on Geode Fragment

Silicon Dioxide (SiO2)

Iron-rich lateritic rock (ironstone)

Goethite–hematite-rich ferruginous material; exact identification requires testing

Iron-stained quartz-rich rock

Likely ferruginous quartzite (quartz, SiO₂, with iron oxides/hydroxides)

Botryoidal chalcedony/geode fragment

Microcrystalline quartz (SiO₂), likely quartz-lined cavity with possible calcite

Quartz Druzy Geode

Silicon Dioxide (SiO2)

Tumbled banded gneiss or amphibolite

Banded metamorphic rock, likely quartz–feldspar–biotite gneiss with amphibole

Iron-stained Quartz

Silicon Dioxide with Iron Oxide (SiO2 with Limonite/Hematite impurities)

Metallic sulfide mineral fragment, likely bornite or chalcopyrite

Bornite (Cu₅FeS₄) or chalcopyrite (CuFeS₂)

Iron-stained milky quartz

Quartz (SiO₂), with iron-oxide staining

Iron-stained quartz specimen

Quartz (SiO₂) with iron-oxide staining, likely limonite/goethite

Amethyst druzy geode fragment

Amethyst, purple variety of quartz (SiO₂), with druzy quartz crystals

Likely weathered quartz-bearing rock

Probably quartz-rich pegmatite or altered feldspathic rock; exact identification is uncertain from the image

Peridot (Olivine)

Magnesium Iron Silicate (Mg,Fe)2SiO4

Baryte with Hematite

BaSO4

Synthetic Resin (Artificial Specimen)

Polyurethane or Polyester Resin

Blue glassy tumbled stone, likely blue chalcedony or slag glass

Chalcedony (microcrystalline SiO₂), possibly man-made blue glass

Iron-stained quartz

Quartz (SiO₂), likely colored by iron-oxide inclusions or surface staining

Iron-stained quartz-rich rock (likely feldspar-rich granite or pegmatite)

Quartz and feldspar, with iron-oxide staining; exact rock type cannot be confirmed from the image alone

Iron-stained quartz-rich rock

Likely quartz with iron oxides/hydroxides (goethite and/or limonite); exact rock type cannot be determined from the image

Weathered granite

Granite; quartz–feldspar–mica plutonic rock

Scoria (vesicular volcanic rock)

Basaltic scoria; chiefly plagioclase, pyroxene, olivine, and volcanic glass

Iron-stained quartz or quartzite fragment

Quartz (SiO₂), possibly iron-oxide-stained quartzite