Sedimentary (Secondary Classification For A Weathered Mineral Specimen)

Botryoidal hematite (ironstone)

Hematite, Fe₂O₃; likely a botryoidal or massive iron-oxide specimen

Agate / Chalcedony

Silicon dioxide (SiO2)

Quartz Geode

Silicon Dioxide (SiO2) in Geodic Cavity

Limonite

Limonite (Hydrated iron oxide mixture, FeO(OH)·nH2O)

Vesicular basalt (probable)

Basalt, typically composed of plagioclase, pyroxene, and olivine

Weathered granite or granitic pegmatite fragment

Granite; chiefly quartz, feldspar, and mica (variable composition)

Quartz Vein in Host Rock

Silicon dioxide (SiO2) veining in silicate matrix

Small pale stone, possibly quartz or limestone

Indeterminate from image; likely quartz (SiO₂) or calcite-rich limestone (CaCO₃)

Quartz (Jasper / Chert)

Silicon Dioxide (SiO2)

Turquoise

Hydrous phosphate of copper and aluminium - CuAl6(PO4)4(OH)8·4H2O

Quartzite with Iron inclusions

Metamorphosed Sandstone (SiO2 with Fe2O3)

Rounded quartz-rich river pebble

Quartz (SiO₂), likely derived from quartzite or granitic rock

Quartz (Tumbled)

Silicon Dioxide (SiO2)

Earthy Hematite / Goethite Surface

Iron Oxide (Fe2O3 – α-FeO(OH))

Carnelian Agate

Carnelian (Silicon Dioxide - SiO2)

Botryoidal Hematite

Hematite (Iron(III) oxide, Fe2O3)

Quartz (Citrine / Yellow Quartz)

Silicon Dioxide (SiO2)

Satin Spar (Gypsum)

Hydrous Calcium Sulfate (CaSO4·2H2O)

Limonite/Goethite Iron Concretion

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

Limonite

FeO(OH)·n(H2O)

Rhodochrosite

Manganese Carbonate (MnCO3)

Weathered sandstone or iron-stained sedimentary pebble

Quartz-rich sandstone; exact identification requires a fresh surface and tests

Rhodochrosite

Manganese Carbonate (MnCO3)

Vesicular basalt (likely iron-rich volcanic scoria)

Basalt; predominantly plagioclase, clinopyroxene, olivine, and iron oxides

Shale with Iron Staining

Fissile Argillaceous Sedimentary Rock

Quartz pebble (Agate / Chalcedony)

Silicon Dioxide (SiO2)

Tumbled Moss Agate

Silicon Dioxide (SiO2) with inclusions of manganese or iron oxide

Gossan (with Limonite/Hematite coating)

Ferruginous Gossan (Fe2O3·nH2O / Fe2O3)

Blue Calcite

Calcium Carbonate (CaCO3)

Azurite Malachite

Azurite (Cu3(CO3)2(OH)2) and Malachite (Cu2CO3(OH)2)

Sandstone (Banded)

Arenite (SiO2 with iron oxide impurities)

Chalcedony (Common Opal or Agate variant)

Silicon dioxide (SiO2) with trace hydration

Quartz (Milky/Common)

Silicon Dioxide (SiO2)

Quartz Geode

Silicon Dioxide (SiO2)

Vesicular volcanic rock, likely weathered scoria

Scoria (vesicular basaltic-andesitic volcanic rock), composition approximately plagioclase, pyroxene, and volcanic glass

Quartz pebble

Silicon dioxide (SiO2)

Botryoidal Quartz Cluster (Druzy Stalactitic Quartz)

Silicon Dioxide (SiO2)

Quartz (Smoky/Milky)

Silicon Dioxide (SiO2)

Iron Gossan (Limonite/Goethite)

Hydrated Iron Oxides (FeO(OH)·nH2O) from oxidation zones

Milky Quartz Pebble

Quartz (Silicon Dioxide - SiO2)

Banded Agate

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Chert (Pebble)

Microcrystalline to Cryptocrystalline Quartz (SiO2)