Metamorphic (Altered Igneous Rock)

Greenstone / altered basalt (likely serpentinite or chlorite-rich rock)

Chlorite–actinolite schist or weakly metamorphosed basalt; exact identification requires testing

Serpentinized ultramafic rock (serpentinite)

Serpentinite, dominated by serpentine-group minerals (antigorite, lizardite, chrysotile), commonly with magnetite and relict olivine/pyroxene

Tumbled river pebble, likely basalt or andesite

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

Rhodonite-bearing metamorphic pebble

Rhodonite (MnSiO₃) in manganese-rich silicate rock, possibly with quartz or feldspar

Weathered granitic rock fragment

Likely granite or granodiorite; quartz–feldspar–mica aggregate

Weathered iron-rich metamorphic rock, possibly schist or metabasalt

Provisional identification: chlorite–quartz–feldspar schist or altered basalt; exact mineralogy requires testing

Tumbled jasper or rhyolitic volcanic rock

Microcrystalline quartz-bearing rhyolite/jasper; commonly quartz (SiO₂), feldspar, and iron-oxide minerals

Unakite (likely)

Epidote–K-feldspar–quartz aggregate; epidote: Ca₂(Al,Fe³⁺)₃Si₃O₁₂(OH)

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)

Jasper and Epidote Breccia

Silicified Brecciated Rock with Epidote

Greenstone pebble (likely altered basalt/serpentinite)

Chlorite–epidote amphibolite or serpentinized mafic rock; exact identification requires testing

Tumbled granite or granitic pebble

Granite, a quartz–feldspar–mica plutonic rock

Pegmatitic granite (quartz–feldspar–mica rock)

Granitic pegmatite; primarily quartz (SiO₂), alkali/plagioclase feldspar, and minor mica, with iron-oxide staining

Quartz-bearing conglomeratic rock with orange feldspar/calcite inclusion

Probably porphyritic granite or granitic pegmatite; exact identification requires a thin section or tests

Serpentine-rich metamorphic rock

Serpentinite, likely antigorite/lizardite with magnetite and possible chlorite or talc

Polished basalt pebble (likely basalt with quartz/zeolite veins)

Basalt; mainly calcic plagioclase and pyroxene, with possible alteration minerals such as quartz, calcite, or zeolites

Weathered granitic rock (probable granite/granodiorite)

Granite–granodiorite; chiefly quartz, feldspar, and mica/amphibole

Porphyritic volcanic rock (likely rhyolite or andesite)

Porphyritic rhyolite–andesite; fine volcanic groundmass with feldspar and mafic phenocrysts

Weathered porphyritic volcanic rock

Likely andesite or dacite, with feldspar phenocrysts in a fine-grained groundmass

Weathered porphyritic granite with lichen

Granite; predominantly quartz, feldspar, and mica (approximate composition)

Serpentine-rich metamorphic rock (possibly serpentinite)

Serpentinite; chiefly antigorite, lizardite, or chrysotile with possible magnetite and carbonate minerals

Serpentinized ultramafic rock (likely serpentinite)

Serpentinite; chiefly serpentine-group minerals (chrysotile, lizardite, antigorite), with olivine/pyroxene relics and possible magnetite

Vesicular basalt (likely olivine basalt)

Basalt; primarily plagioclase, clinopyroxene, olivine, and volcanic glass

Weathered quartz-bearing rock, possibly quartzite or feldspathic sandstone

Quartzite (SiO₂-rich), with possible iron-oxide staining and feldspar/mica impurities

Granitoid (with Epidote and Orthoclase)

Crystalline Felsic Intrusive Rock (containing SiO2, KAlSi3O8, and Ca2(Al2,Fe)(Si2O7)(SiO4)O(OH))

Lapis Lazuli

Complex metamorphic rock containing Lazurite ((Na,Ca)8(AlSiO4)6(SO4,S,Cl)2), Calcite, and Pyrite

Iron-stained metamorphic rock, likely quartzite or jasper

Quartz-rich rock dominated by SiO₂, with iron oxides/hydroxides (hematite, goethite) and possible clay or mica

Serpentine-rich ultramafic rock

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

Weathered granite or granitic gneiss

Quartz–feldspar–mica granitic rock; possible biotite gneiss

Serpentinized ultramafic rock (probable serpentinite)

Serpentinite, dominated by serpentine-group minerals (lizardite/chrysotile/antigorite), with possible magnetite and carbonate

Tumbled jasper or rhyolitic porphyry

Silicic volcanic rock, likely rhyolite (quartz- and feldspar-rich), possibly jasperized

Weathered basaltic cobble

Basalt, likely amygdaloidal or vesicular basalt

Quartz-rich veined rock, likely milky quartz with feldspar or calcite

Quartz (SiO₂), possibly in a quartz–feldspar or quartz–calcite vein

Weathered copper-bearing volcanic rock (likely altered basalt/andesite)

Hydrothermally altered basalt or andesite; green coloration may reflect chlorite, epidote, or copper minerals such as chrysocolla

Likely serpentinite or serpentinized ultramafic rock

Serpentinite; chiefly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), possibly with magnetite and minor olivine/pyroxene

Rounded green-gray pebble, likely serpentinite or altered basalt

Probable serpentinite (hydrated ultramafic rock) or greenstone; image insufficient for certain identification

Serpentine (rough serpentine-rich rock)

Serpentine-group minerals, chiefly antigorite and/or lizardite; composition broadly Mg₃Si₂O₅(OH)₄

Greenstone / serpentinized ultramafic rock (probable)

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

Lapis Lazuli

Lazurite (primary mineral component), (Na,Ca)8(AlSiO4)6(S,SO4,Cl)1-2

Weathered purple rhyolite (probable porphyritic volcanic rock)

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

Likely weathered iron-rich rock

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

Weathered porphyritic pebble

Likely porphyritic volcanic rock, possibly andesite or rhyolite