Sedimentary (Secondary Classification For A Weathered Mineral Specimen)

Quartz-rich rock, likely milky quartz vein material

Quartz (SiO₂), possibly quartzite or quartz-bearing pegmatite

Iron-rich meteorite candidate

Probable stony-iron or iron meteorite; exact classification requires testing

Iron-rich meteorite candidate

Unclassified stony-iron or iron meteorite; requires testing for confirmation

Quartz-rich breccia or silicified breccia

Cryptocrystalline quartz/chalcedony (SiO₂) with iron oxides and dark lithic fragments; exact classification is uncertain from the photograph

Quartz Pebble (likely Chalcedony or Quartzite)

Silicon Dioxide (SiO2)

Likely iron-stained quartz or feldspar fragment

Quartz (SiO₂) or potassium feldspar (KAlSi₃O₈), uncertain from image

Polished pink granite cobble

Granite, chiefly potassium feldspar, plagioclase, quartz, and biotite/hornblende

Rounded river cobble, likely weathered sandstone or quartz-rich metasandstone

Indeterminate sandstone; commonly quartz (SiO₂) with feldspar, lithic grains, and iron-oxide cement

Limonite (Iron Ore)

Hydrated ferric oxide (FeO(OH)·nH2O)

Botryoidal Hematite (included in Quartz/Limonite matrix)

Fe2O3 (Hematite) on Quartz (SiO2) / Limonite

Agate (Chert/Chalcedony)

Silicon Dioxide (SiO2)

Iron-rich meteorite candidate

Unclassified stony-iron or iron meteorite candidate; possibly limonite/hematite-bearing terrestrial rock

Lichen-covered granite or granitic gneiss

Granite: quartz + feldspar + mica; possibly gneiss if foliation is confirmed

Small pale rock fragment

Indeterminate; possibly quartz, calcite, or a weathered feldspar-rich fragment

Likely quartz-rich rock fragment

Indeterminate; probably microcrystalline quartz (SiO₂) with minor feldspar or weathering minerals

Limonite (often after Hematite or Goethite)

Limonite (FeO(OH)·nH2O)

Quartz-rich rock, possibly granite or pegmatite fragment

Likely quartz–feldspar aggregate; exact identification is uncertain from the photograph

Chert on Volcanic Host Rock

Sedimentary Chert (SiO2) within Basalt or Andesite

Red jasper pebble

Microcrystalline quartz (chalcedony), SiO₂, colored by iron oxides

Limonite Concretion

FeO(OH)qnH2O (Hydrated iron(III) oxide-hydroxide mixture)

Possible iron meteorite

Iron–nickel meteorite, commonly kamacite-taenite (Fe-Ni alloy)

Possible ironstone concretion or weathered mineral nodule

Iron-oxide-rich concretion, likely goethite/limonite; identification uncertain from the photo

Vesicular basalt (possibly weathered scoria)

Basaltic volcanic rock; chiefly plagioclase, clinopyroxene, and Fe–Mg oxides, with vesicles from trapped gas

Quartz Geode

Silicon Dioxide (SiO2)

Rounded gray river pebble, likely basalt or andesite

Fine-grained mafic to intermediate volcanic rock; exact identification requires testing

Ammonite fossil

Fossilized ammonoid cephalopod; likely an involute ammonite, exact genus/species indeterminate

Likely mica-rich granite pegmatite

Granitic pegmatite, composed mainly of quartz and feldspar with visible mica (likely muscovite or biotite)

Jasper Agate

Chalcedony (Silicon Dioxide - SiO2)

Quartz-rich rock, possibly yellow chalcedony or weathered quartzite

Quartz (SiO₂), likely microcrystalline chalcedony with iron-oxide staining

Copper Ore (Malachite and Limonite bearing rock)

Copper-bearing rock with secondary copper minerals

Limonite (Yellow Ochre)

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

Erythrite

Erythrite (Cobalt Bloom) - Co3(AsO4)2·8H2O

Conglomeratic breccia

Clast-supported polymictic conglomerate/breccia, cemented by silica- or carbonate-rich matrix

Vesicular basalt (scoriaceous volcanic rock)

Basalt, chiefly plagioclase, pyroxene, and commonly olivine; vesicles may be lined with secondary minerals

Likely iron-rich meteorite fragment

Undetermined stony-iron or iron meteorite; mineralogy may include Fe–Ni metal, troilite, and silicates

Limonite (Ironstone Concretion)

Limonite (FeO(OH)·nH2O)

Dark mafic rock, possibly basalt or meteorite-like specimen

Likely basalt (plagioclase–pyroxene assemblage); meteorite identification cannot be confirmed visually

Possible iron meteorite

Fe–Ni iron meteorite, possibly an ordinary chondrite or weathered iron-rich specimen

Basalt with Secondary Mineralization (Likely Zeolites or Calcite)

Aphanitic mafic volcanic rock with secondary mineral inclusions (e.g., CaAl2Si3O10·3H2O for Scolecite)

Iron meteorite (likely weathered octahedrite)

Fe–Ni kamacite–taenite alloy, possibly a Canyon Diablo-type specimen

Amygdaloidal Basalt

Extrusive mafic igneous rock with amygdules

Reddish-brown iron-rich rock, possibly weathered basalt or laterite

Indeterminate; likely iron-oxide-stained basalt (plagioclase–pyroxene) or ferruginous laterite (goethite/hematite)