Industrial By Product

Bismuth crystal

Bismuth (Bi), commonly laboratory-grown

Limonite (Ironstone) Concretion

FeO(OH)·nH2O (Hydrous ferric oxide)

Quartzite

Quartzite (SiO2-rich metamorphic rock)

Galena

Galena (lead sulfide, PbS)

Tumbled milky quartz

Quartz (silicon dioxide, SiO₂)

Weathered quartz-rich rock, likely quartzite

Quartzite; predominantly quartz (SiO₂), possibly with feldspar and iron-oxide staining

Small seashell fossil or shell fragment

Likely calcium-carbonate shell material, chiefly aragonite or calcite; exact species indeterminate

Likely weathered quartz-bearing rock

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

Chert (and associated Sedimentary rocks)

Microcrystalline Silica (SiO2)

Pumice

Volcanic pumice; chiefly vesicular volcanic glass composed of rhyolitic to dacitic silicates

Weathered quartz-rich rock, possibly milky quartz in altered host rock

Milky quartz (SiO₂), with probable iron-oxide staining and a fine-grained host matrix

Likely graphite-rich schist (possibly galena-bearing metamorphic rock)

Graphite schist; chiefly quartz–mica with graphite (identification uncertain from photograph)

Weathered quartz-rich rock, likely quartzite or silicified sandstone

Quartzite; predominantly microcrystalline to granular SiO₂, possibly with iron-oxide impurities

Pumice

Pumice (Volcanic Rock)

Chert (Flint)

Silicon dioxide (SiO2)

Chert (Flint)

Silicon Dioxide (SiO2)

Marble

Metamorphic rock primarily composed of Calcite (CaCO3)

Pumice

Pumice (Amorphous volcanic glass)

Limestone

Calcium Carbonate (CaCO3)

Pumice

Vesicular Rhyolite or Andesite (Amorphous volcanic glass)

Polished basalt pebble

Basalt, a fine-grained mafic volcanic rock; commonly composed of plagioclase, pyroxene, and minor olivine or magnetite

Native copper

Copper (Cu), often with malachite, cuprite, or matrix minerals

Black basalt pebble

Basalt; chiefly plagioclase feldspar, pyroxene, and commonly olivine

Weathered quartz-rich rock, possibly granite or gneiss fragment

Likely granitic rock composed mainly of quartz, feldspar, and minor mica/iron oxides

Polished basalt pebble

Basalt, a fine-grained mafic volcanic rock composed chiefly of plagioclase and pyroxene, commonly with olivine

Polished serpentine-rich stone

Serpentinite, primarily serpentine-group minerals (antigorite, lizardite, or chrysotile)

Greenstone, likely serpentinite

Serpentinite; chiefly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), possibly with magnetite and chlorite

Weathered basaltic rock (likely basalt)

Basalt; primarily plagioclase feldspar, pyroxene, and possibly olivine, with surface alteration minerals

Granite

Granite

Polished native copper

Native copper (Cu), likely with cuprite/tenorite oxidation products

Pyrite-bearing quartz vein rock

Pyrite (FeS₂) in quartz, possibly with iron-oxide weathering products

Malachite

Malachite, Cu₂CO₃(OH)₂; a banded botryoidal copper carbonate specimen

Rounded volcanic rock, likely basalt

Basalt (fine-grained mafic igneous rock; commonly plagioclase, pyroxene, and olivine)

Weathered feldspar-rich granite or granitic pegmatite

Altered granite/pegmatite, composed mainly of quartz (SiO₂), alkali feldspar, plagioclase, and dark mica or amphibole

Weathered porphyritic volcanic rock (likely andesite or basalt)

Fine-grained intermediate-to-mafic volcanic rock; likely andesite/basalt composed mainly of plagioclase, pyroxene, and possibly altered iron-bearing minerals

Grey Chalcedony (Tumbled)

Chalcedony (SiO2)

Iron-rich lateritic rock / weathered ironstone

Ferruginous laterite, commonly hematite–goethite-rich (Fe₂O₃–FeO(OH))

Weathered iron-rich rock, likely limonite-bearing sandstone or laterite

Limonite/goethite-rich ferruginous rock; composition commonly FeO(OH)·nH₂O with quartz and clay minerals

Limestone (likely weathered or plaster-coated)

Calcite-rich carbonate rock; primarily CaCO₃

Sea Glass

Amorphous Silica (Anthropogenic glass) - SiO2

Marble

Marble (primarily Calcite, CaCO3 or Dolomite, CaMg(CO3)2)

Gabbroic or basaltic rock with weathered veins

Likely mafic igneous rock, possibly olivine gabbro or porphyritic basalt; exact identification requires testing