Sedimentary (Secondary Classification For A Weathered Mineral Specimen)

Weathered basalt pebble

Basalt, a fine-grained mafic volcanic rock; likely containing plagioclase and pyroxene with weathering products

Limonite (Iron Ore)

FeO(OH)·nH2O (Hydrous ferric oxide)

Limonite or Ironstone

Hydrated iron oxide-hydroxide, approximately FeO(OH)·n(H2O)

Weathered vesicular basalt (probable)

Basalt; primarily plagioclase, clinopyroxene, and iron-rich olivine, with secondary weathering minerals

Limonite

FeO(OH)•nH2O

Iron-stained quartz-rich cobble, possibly weathered granite or quartz vein rock

Quartz–feldspar aggregate with iron-oxide staining; exact classification is uncertain from the photograph

Hematite

Iron Oxide (Fe2O3)

Likely iron-rich rock or metallic mineral fragment

Uncertain; possibly limonite/goethite-rich material or weathered iron meteorite fragment

Limonite with Hematite

Hydrated Iron(III) Oxide-Hydroxide (FeO(OH)·nH2O)

Limonite/Hematite Ironstone

Goethite-rich Ironstone (FeO(OH) · nH2O)

Limonite (Iron Ore)

Limonite (Hydrous iron(III) oxide-hydroxide mixture, primarily FeO(OH)·nH2O)

Quartz Pebble

Silicon Dioxide (SiO2)

Quartz Crystal Cluster

Silicon Dioxide (SiO2)

Limonite (Iron Ore)

Limonite (FeO(OH)·nH2O)

Red Siltstone

Siltstone (composed mainly of SiO2 and Fe2O3)

Weathered basalt (possibly vesicular basalt)

Basalt; predominantly plagioclase, pyroxene, and commonly olivine

Rough Agate/Chert Nodules

Cryptocrystalline Quartz (SiO2)

Weathered basalt (likely altered basalt)

Basalt, chiefly plagioclase feldspar and pyroxene, with possible chlorite/epidote alteration

River Stones (Quartzite and Sandstone)

Quartzite / Sedimentary Rock (SiO2 dominant)

Carnelian Agate

Silicon Dioxide (SiO2) with iron oxide impurities

Limonite with Hematite

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

Porphyritic basalt

Vesicular/porphyritic basalt, chiefly plagioclase and pyroxene with iron-oxide alteration

Ironstone Matrix with Jasper / Chert

Ferruginous Chert / Limonitic Jasper (SiO2 with Fe-oxides)

Rounded granitic gneiss or granitoid boulder

Biotite-bearing orthogneiss; chiefly quartz, feldspar, and biotite

Limonite (Iron Ore)

Limonite (mixed iron hydroxides, primarily FeO(OH)·nH2O)

Pitted vesicular basalt, likely copper-stained

Basalt (mafic volcanic rock), possibly with secondary copper minerals such as chrysocolla or malachite

Tumbled dark limestone or basalt with a pale mineral vein

Likely micritic limestone (calcite, CaCO₃), possibly basalt with a calcite/quartz vein

Turquoise

Hydrated copper aluminum phosphate, CuAl₆(PO₄)₄(OH)₈·4H₂O

Limonite / Goethite (Iron Ore Mineral nodule)

FeO(OH)·nH2O / FeO(OH)

Vesicular Basalt

Basalt (Mafic Extrusive Volcanic Rock)

Milky Quartz Pebble with Inclusions

Quartz (SiO2) with chlorite or mica inclusions

Botryoidal Goethite

Goethite (α-Fe3+O(OH))

Chalcedony (Agate / Quartz Pebble)

Silicon Dioxide (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Weathered jasper-rich ironstone

Brecciated jasper/chert with iron oxides and hydroxides (SiO₂ with hematite, goethite, and limonite)

Limonite / Ironstone

Hydrated Iron Oxide (FeO(OH)·nH2O)

Green Tourmaline

Elbaite (Na(Li,Al)3Al6(BO3)3Si6O18(OH)4)

Altered volcanic rock, possibly andesite

Likely porphyritic andesite or dacite with secondary chlorite/epidote and quartz–calcite veins

Limonite and Goethite (Ironstone)

Hydrous Iron Oxide Mixture (FeO(OH)·nH2O)

Quartz Crystal Cluster

Silicon Dioxide (SiO2)

Chalcedony (Agate / Moss Agate)

Silicon Dioxide (SiO2)

Black Sapphire (Basaltic Blue Sapphire)

Corundum (Al2O3)