Industrial By Product

Weathered copper-bearing rock, likely malachite-bearing matrix

Malachite (Cu₂CO₃(OH)₂) with iron-oxide-stained host rock; exact identification requires testing

Weathered iron-rich stone, possibly limonite-bearing rock

Limonite/goethite-rich material; composition commonly approximated as hydrated iron oxides, FeO(OH)·nH₂O

Galena-bearing sulfide fragment

Galena (PbS), possibly with quartz or carbonate gangue

Native metallic specimen, possibly galena or a sulfide-rich ore fragment

Tentatively galena (lead sulfide, PbS), possibly mixed with iron/copper sulfides

Milky Quartz Pebble

Silicon Dioxide (SiO2)

Weathered granite (probable)

Granite; mainly quartz, feldspar, and mica

Iron-rich concretion or weathered ironstone pebble

Goethite/limonite-bearing ironstone; commonly an iron-oxide concretion (FeO(OH)·nH₂O, variable)

Brown shale or mudstone fragment

Likely fissile claystone/shale, composed mainly of compacted clay minerals, quartz, and minor iron oxides

Galena (likely)

Galena, lead sulfide (PbS)

Milky quartz-rich rock

Quartz, crystalline silica (SiO₂), likely massive milky quartz with minor feldspar or mica

Milky quartz

Quartz (silicon dioxide, SiO₂)

Limestone

Calcium Carbonate (CaCO3)

Quartzite

Quartzite (SiO2)

Pumice

Pumice (Volcanic Glass with Vesicular Texture)

Milky quartz-rich rock

Quartz (SiO₂), likely massive milky quartz with minor iron-oxide staining and attached host material

Scoria

Vesicular Mafic Extrusive Igneous Rock

Pumice

Pumice (Vesicular volcanic glass)

Chert (specifically Flint or Nodular Chert)

Silicon Dioxide (SiO2)

Limestone

Calcium Carbonate (CaCO3)

Limestone

Calcium Carbonate (CaCO3)

Rounded basalt pebble

Basalt; fine-grained mafic volcanic rock, chiefly plagioclase and pyroxene with minor olivine or iron oxides

Rounded basalt pebble

Basalt; fine-grained mafic volcanic rock, commonly dominated by plagioclase and pyroxene with minor olivine

Flint

SiO2 (Microcrystalline quartz / Chert)

Chert / Flint

Cryptocrystalline quartz (SiO2)

Tumbled white quartz pebble

Quartz (silicon dioxide, SiO₂), possibly milky quartz

Milky quartz with iron-oxide staining

Quartz, silicon dioxide (SiO₂), likely massive milky quartz

Chert

Chert (SiO2, Silicon Dioxide)

Pumice

Highly vesicular volcanic glass (unnamed scientific variant: Rhyolitic/Andesitic Pumice)

Quartzite

Quartzite (SiO2)

Pumice

Vesicular volcanic glass

Weathered sandstone or altered volcanic rock

Indeterminate; likely quartz–feldspar-rich sandstone, possibly tuff

Quartz-rich pegmatitic rock, likely pink granite or quartzite

Probable pink granite/pegmatite; chiefly quartz (SiO₂), potassium feldspar, and minor mica

Amethyst quartz cluster

Quartz, SiO₂; purple variety colored mainly by iron impurities and irradiation

Tumbled greenstone-like pebble

Likely serpentine or chlorite-rich metamorphic rock; exact identification requires testing

Weathered basalt (likely vesicular basalt)

Basalt; primarily plagioclase feldspar, pyroxene, and often olivine (approx. 45–52% SiO₂)

Polished basalt pebble

Basalt; primarily plagioclase feldspar, pyroxene, and commonly olivine or iron oxides

Vesicular basalt (likely scoriaceous basalt)

Basalt; chiefly plagioclase, clinopyroxene, and Fe–Mg minerals, with possible olivine and iron oxides

Chrysoprase-bearing quartz matrix (probable)

Nickeliferous chalcedony/quartz, SiO₂, with green nickel minerals such as garnierite or népouite

Botryoidal Hematite (Iron Stone Conglomerate)

Hematite (Fe2O3) in sedimentary matrix

Quartz-rich metamorphic rock, likely quartzite or quartz vein in schist

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

Weathered mafic rock fragment

Likely basalt or volcanic breccia; identification is uncertain from the photograph

Crushed granite aggregate

Granite, a coarse-grained felsic intrusive igneous rock composed mainly of quartz, alkali feldspar, plagioclase, and minor mica/amphibole