Metamorphic (Altered Igneous Rock)

Weathered greenstone pebble

Metamorphosed mafic rock, commonly metabasalt or greenschist (exact identification requires testing)

Unakite

Unakite (Altered Granite)

Tumbled granite or granitic pebble

Granite; primarily quartz, feldspar, and mica (exact variety uncertain from the image)

Quartz vein in dark host rock

Quartz (SiO₂), likely in basalt, gabbro, or altered mafic rock

Vesicular basalt with secondary zeolite/mineral crusts

Basalt, chiefly plagioclase–pyroxene ± olivine; cavities partly filled by zeolites or calcite

Greenstone (Amygdaloidal Basalt)

Amygdaloidal Basalt (frequently composed of Plagioclase Feldspar, Pyroxene, and Olivine with Chlorite inclusions)

Polished orbicular jasper

Orbicular jasper; microcrystalline quartz (SiO₂) with iron oxides and altered volcanic minerals

Serpentine-rich ultramafic rock

Serpentinite (predominantly serpentine-group minerals: lizardite, chrysotile, and/or antigorite)

Weathered feldspathic rock, likely granite or granitic pegmatite

Quartz–feldspar–mica aggregate; exact species indeterminate from the image

Weathered basalt (likely vesicular basalt)

Basalt; primarily plagioclase feldspar, pyroxene, and commonly olivine

Weathered river stones, likely basaltic andesite and related volcanic rocks

Fine-grained mafic/intermediate volcanic rocks; commonly basalt (plagioclase + pyroxene ± olivine) or andesite (plagioclase + pyroxene ± amphibole)

Pale green rounded boulder, likely altered serpentinite or greenstone

Probable serpentinized ultramafic rock; exact identification requires testing

Quartz-rich vein rock, possibly milky quartz in altered host rock

Quartz (SiO₂), likely with weathered silicate minerals and iron/manganese staining

Polished greenstone (likely serpentinite or chlorite-rich schist)

Serpentinite/chlorite-rich ultramafic metamorphic rock; composition commonly dominated by serpentine-group minerals, chlorite, magnetite, and minor amphibole or pyroxene

Weathered quartz-rich rock, possibly granite or quartzite

Indeterminate; likely quartz–feldspar aggregate, possibly altered granite

Likely weathered iron-rich rock

Probable basalt or limonite/goethite-stained mafic rock; exact identification requires testing

Porphyritic basalt (likely olivine basalt)

Basalt; fine-grained plagioclase–pyroxene matrix with possible olivine phenocrysts

Polished tiger iron

Tiger iron: banded quartz (SiO₂), red jasper, and crocidolite-derived fibrous iron oxides

Weathered purple rhyolite (probable porphyritic volcanic rock)

Rhyolite, commonly quartz–alkali-feldspar–plagioclase with minor biotite or iron oxides

Green Andesite (or Greenstone / Altered Volcanic Rock)

Intermediate Volcanic Rock with Chlorite/Epidote Alteration

Quartz-veined metamorphic rock, likely greenschist or altered basalt

Chlorite–actinolite schist or metabasalt with a milky quartz vein

Pink feldspar-bearing granite or pegmatitic rock

Granite/pegmatite, chiefly quartz (SiO₂), potassium feldspar (KAlSi₃O₈), plagioclase, and dark mica/amphibole; pink areas may be K-feldspar or garnet.

Granite (likely weathered, pegmatitic granite)

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

Lapis Lazuli

Lapis lazuli (complex rock composed of Lazurite (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2, Pyrite, and Calcite)

Polished Rhodonite Obelisk

Rhodonite (Manganese Iron Magnesium Calcium Silicate) - (Mn,Fe,Mg,Ca)SiO3

Weathered iron-rich basalt or volcanic breccia

Mafic volcanic rock, likely basalt; composition dominated by plagioclase and pyroxene with iron oxides

Iron-stained weathered volcanic rock (probable basalt/andesite)

Altered basaltic–andesitic rock, chiefly plagioclase and pyroxene with iron oxides/hydroxides

Tumbled yellow quartz-rich stone, likely yellow jasper or quartzite

Jasper/quartzite; mainly microcrystalline quartz (SiO₂), with iron-oxide staining

Weathered porphyritic pebble

Likely porphyritic volcanic rock, possibly andesite or rhyolite

Weathered basalt (likely altered basalt)

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

Tumbled greenstone / serpentinite (probable)

Serpentinite, chiefly Mg-rich serpentine minerals (antigorite, lizardite, chrysotile), possibly mixed with chlorite, magnetite, or carbonate

Weathered gray-green volcanic rock

Likely basaltic andesite or altered basalt; precise identification requires a fresh surface and testing

Unakite

Unakitized granodiorite / Quartz-Epidote-Feldspar rock

Milky quartz vein rock

Quartz, silicon dioxide (SiO₂), likely with iron-oxide staining and minor mica or sulfide minerals

Epidote in Quartz (Unakite-like specimen)

Epidote (Ca2(Al2,Fe)(SiO4)(Si2O7)O(OH)) in Quartz (SiO2)

Vesicular quartz-rich rock, possibly weathered rhyolite or hydrothermal quartz

Likely quartz (SiO₂) with altered feldspar, iron oxides, and cavities; exact identification requires testing

Rounded dark pebble, likely basaltic andesite

Fine-grained mafic volcanic rock; probable basalt or andesite, identification uncertain from image alone

Tiger's Eye

Silicon dioxide (SiO2) with fibrous inclusions of crocidolite

Pink Granite (Unakite-bearing or Epidote-bearing Granite)

Plutonic Igneous Rock (Granite)

Unakite

Unakite (Altered Granite)

Rounded green-gray river cobble

Likely altered basalt or andesite; exact identification requires a fresh surface and tests

Granite (likely biotite granite or granodiorite)

Coarse-grained granitoid composed mainly of quartz, feldspar, and dark biotite/amphibole