Metamorphic (Altered Igneous Rock)

Greenstone (likely altered basalt)

Metabasalt/greenschist; chiefly chlorite, actinolite, epidote, albite, and quartz

Brecciated jasper/quartz-rich polymictic rock

Silicified breccia, chiefly microcrystalline quartz (SiO₂) with iron-oxide and sulfide staining

Weathered granite or granitic gneiss

Granite; predominantly quartz, feldspar, and mica, possibly altered to gneiss

Tumbled greenish stone, likely altered basalt or serpentinite

Probable basaltic/mafic rock with secondary chlorite, epidote, or serpentine minerals

Gabbroic or basaltic rock with weathered veins

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

Polished serpentine-rich metamorphic rock

Serpentinite, chiefly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), with possible magnetite, chlorite, or talc

Tumbled granite

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

Tumbled greenstone pebble

Greenstone (metamorphosed mafic volcanic rock; commonly chlorite, actinolite, epidote, and albite)

Lapis Lazuli (in jewelry setting)

Na8[Al6Si6O24]n(S,Cl,SO4,OH)2 (Lazurite-rich rock)

Smoky Quartz

Silicon dioxide (SiO2)

Porphyritic Basalt

Porphyritic Mafic Volcanic Rock

Weathered metamorphic boulder, likely schist or gneiss

Quartz–feldspar–mica metamorphic rock; exact identification requires a fresh surface

Weathered iron-rich rock, possibly laterite or altered basalt

Probable ferruginous basalt/lat eritic material; exact identification requires testing

Lapis Lazuli

Lapis Lazuli (Complex rock containing Sodalite, Lazurite, Calcite, and Pyrite)

Banded metamorphic rock, likely gneiss or schist

Quartz–feldspar–mica gneiss/schist; exact identification requires thin-section or tests

Polished purple-and-cream jasper (likely)

Silica-rich microcrystalline quartz/chalcedony, SiO₂, colored by iron/manganese minerals

Polished serpentine (likely greenstone)

Serpentine-group minerals, chiefly antigorite/lizardite: Mg₃Si₂O₅(OH)₄

Iron-rich rock, possibly weathered basalt or ironstone

Tentatively ferruginous basalt; exact identification requires testing

Serpentine (likely antigorite/lizardite)

Serpentinite; chiefly serpentine-group minerals, Mg₃Si₂O₅(OH)₄

Vesicular basalt (possibly slag-contaminated)

Basalt; chiefly plagioclase and pyroxene, with possible olivine and secondary minerals

Greenstone / altered basalt (probable)

Chlorite–epidote–actinolite aggregate; commonly metabasalt (greenstone)

Tumbled serpentine-rich altered rock

Serpentinite, likely antigorite/lizardite with accessory carbonate, quartz, or iron oxides

Lapis Lazuli

Complex mixture of minerals (lazurite, calcite, pyrite, and sodalite); (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2

Weathered quartz-rich rock, likely silicified limestone or quartzite

Microcrystalline quartz (SiO₂), possibly with calcite (CaCO₃) and iron-oxide staining

Likely weathered basalt

Basalt; primarily plagioclase feldspar, pyroxene, and often olivine

Tumbled greenstone / serpentine pebble

Serpentinite, dominated by serpentine-group minerals (Mg₃Si₂O₅(OH)₄)

Quartz-rich rock with a purple amethyst-like cavity

Likely quartz vein or amethyst-bearing geode; purple area may be quartz (SiO₂) colored by trace iron

Citrine Quartz (Yellow Quartz)

Silicon Dioxide (SiO2) with iron impurities

Polished green serpentine

Serpentinite, chiefly antigorite/lizardite Mg₃Si₂O₅(OH)₄

Tumbled blue-gray stone, likely basalt

Basalt (fine-grained mafic volcanic rock; chiefly plagioclase and pyroxene, commonly with magnetite)

Weathered granite or granitic gneiss slab

Granitic rock, chiefly quartz, feldspar, and mica; exact identification is uncertain from the photograph

Greenstone pebble (likely serpentinite)

Serpentinite, composed mainly of serpentine-group minerals

Weathered metal-rich igneous rock, likely basalt or komatiitic peridotite

Probable altered mafic–ultramafic rock containing pyroxene/amphibole, olivine, iron oxides, and possible metallic sulfides

Iron-stained quartz vein rock

Quartz-rich vein material, predominantly SiO₂, with iron oxyhydroxides (goethite/limonite) and likely sulfide alteration

Tumbled serpentine or soapstone pebble

Serpentine-group minerals, chiefly antigorite/lizardite; possibly talc-rich steatite

Quartz-rich metamorphic rock, likely mica schist or gneiss

Quartz–feldspar–mica schist/gneiss; commonly containing biotite or muscovite

Rounded greenstone cobble

Likely greenschist or altered basalt; composition commonly chlorite, epidote, actinolite, albite, and quartz

Lapis Lazuli

Lapis lazuli (Complex silicate mixture including Lazurite, Calcite, and Pyrite)

Likely serpentinized ultramafic rock (serpentinite)

Serpentinite; chiefly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), with possible olivine, pyroxene, magnetite, and talc

Weathered, iron-stained feldspathic rock (probable granite or granitic pegmatite)

Quartz–feldspar granitoid; visible blue grains may be altered feldspar or accessory minerals

Milky quartz-bearing rock (likely quartz vein fragment)

Quartz, silicon dioxide (SiO₂), with probable iron-oxide staining and dark host-rock inclusions

Tumbled yellow-green pebble, likely serpentine or quartzite

Provisional: serpentine-group rock, chiefly Mg₃Si₂O₅(OH)₄; exact identification requires testing