Metamorphic (Altered Igneous Rock)

Likely iron-rich granite or granitic gneiss

Quartz–feldspar rock with iron-oxide staining; exact identification is uncertain from the image

Tumbled pegmatitic granite

Granite, chiefly quartz–feldspar–mica; likely altered pegmatite

Polished green stone, likely chrysoprase or aventurine

Chrysoprase: microcrystalline chalcedony (SiO₂) colored by nickel; possible green aventurine: quartz (SiO₂) with fuchsite

Epidote in Quartz (Unakite-like specimen)

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

Weathered porphyritic volcanic rock (likely basalt/andesite)

Fine-grained mafic to intermediate volcanic rock; probably porphyritic basalt or andesite, composed mainly of plagioclase with pyroxene and iron oxides

Iron-stained quartz-bearing rock, possibly quartzite

Quartzite (mostly SiO₂), with iron-oxide minerals such as hematite/goethite

Rounded granitic pebble

Granite, chiefly quartz–feldspar–mica aggregate

Weathered basaltic rock fragment

Basalt, likely vesicular or altered basalt; primarily plagioclase and pyroxene

Lapis Lazuli

Lapis Lazuli (Complex aggregate of Lazurite, Calcite, and Pyrite)

Weathered basalt (likely amygdaloidal basalt)

Basalt; chiefly plagioclase feldspar and pyroxene, with possible olivine and iron oxides

Waterworn greenstone pebble

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

Weathered granite fragment

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

Weathered granitoid (likely granite or granodiorite)

Granite–granodiorite; primarily quartz, feldspar, and mica

Likely weathered basalt or iron-rich mafic rock

Basalt; chiefly plagioclase feldspar, pyroxene, and minor olivine/iron oxides

Serpentinite (serpentinized ultramafic rock)

Serpentinite; chiefly lizardite, chrysotile, and antigorite, commonly with magnetite and minor chromite or carbonate

Porphyritic basalt or andesite

Porphyritic volcanic rock; typically plagioclase phenocrysts in a fine mafic/intermediate groundmass

Copper-bearing sulfide ore, possibly bornite/chalcopyrite

Likely bornite (Cu5FeS4) and/or chalcopyrite (CuFeS2) in a sulfide-rich host rock

Weathered vesicular volcanic rock (likely pumice or altered basalt)

Vesicular basalt–pumice, compositionally uncertain

Porphyritic basalt (likely vesicular basalt)

Basalt, chiefly plagioclase feldspar and pyroxene, with possible olivine phenocrysts

Serpentinite (likely serpentinized ultramafic rock)

Serpentinite; chiefly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), commonly with magnetite, chromite, and relict olivine/pyroxene

Quartz-bearing rock, possibly weathered granite or pegmatite

Quartz–feldspar–mica aggregate; exact classification is uncertain from the image

Tumbled greenstone (likely serpentinite or green jasper)

Serpentinite, commonly dominated by serpentine-group minerals (Mg₃Si₂O₅(OH)₄); exact identification requires testing

Weathered granitic or gneissic cobble

Likely altered granite/granodiorite; exact identification requires a fresh surface and testing

Epidote (or Epidote-rich rock)

Epidote. Mineral formula: Ca2(Al,Fe)3(SiO4)3(OH).

Rounded greenstone pebble

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

Likely chlorite schist or altered mafic rock

Chlorite–actinolite schist; commonly composed of chlorite, actinolite/amphibole, epidote, and albite

Weathered volcanic rock, likely andesite

Andesite (plagioclase–pyroxene volcanic rock), identification tentative

Banded ironstone (likely iron-rich metamorphic rock)

Ferruginous quartzite or ironstone; exact identification requires examination of a fresh surface

Serpentinite (likely serpentinized ultramafic rock)

Serpentine-group minerals, chiefly lizardite, chrysotile, and/or antigorite; commonly derived from peridotite

Polished pebble, likely basalt or altered volcanic rock

Fine-grained mafic volcanic rock; exact identification requires testing

Propylitic Altered Andesite

Hydrothermally Altered Andesite

Iron-stained quartz-rich rock, possibly weathered granite or pegmatite

Quartz (SiO₂) with probable feldspar and iron-oxide staining; exact identification is uncertain from the photograph

Pegmatitic granite (likely feldspar–quartz–mica rock)

Coarse-grained granitic pegmatite; primarily quartz (SiO₂), feldspar, and mica, with possible epidote or chlorite

Tumbled smoky quartz

Quartz, silicon dioxide (SiO₂), smoky variety

Ruby in Zoisite

Anyolite (composite of Corundum and Zoisite)

Tumbled greenstone (likely serpentine or chlorite-rich metamorphic rock)

Serpentinite, approximately Mg₃Si₂O₅(OH)₄, or chlorite-rich greenstone

Weathered gray rock, likely basalt or andesite

Fine-grained mafic to intermediate volcanic rock; likely basalt (plagioclase ± pyroxene, possibly altered)

Likely weathered granite or granitic gneiss fragment

Quartz–feldspar–mica aggregate; possibly biotite granite or granitoid gneiss

Tumbled amber jasper

Jasper, microcrystalline quartz (SiO₂), colored by iron oxides and dark mineral inclusions

Blue-green metamorphic cobble, probably serpentinite

Serpentinite (serpentine-group minerals; commonly lizardite, chrysotile, and antigorite), possibly altered mafic rock

Lapis Lazuli

Complex metamorphic rock primarily composed of Lazurite ((Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2), Calcite, and Pyrite

Lapis Lazuli

Complex metamorphic rock consisting mainly of Lazurite (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2, Calcite, and Pyrite