Metamorphic (Altered Igneous Rock)

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2)

Likely weathered basalt

Basalt; fine-grained mafic rock composed mainly of plagioclase, pyroxene, and commonly olivine or iron oxides

Pale green rounded boulder, likely altered serpentinite or greenstone

Probable serpentinized ultramafic rock; exact identification requires testing

Weathered granitic rock (likely granite or granodiorite)

Granite–granodiorite; quartz + feldspar + biotite/hornblende

Mixed rough mineral specimens, likely quartz-bearing rocks

Probable quartz (SiO₂), with possible feldspar, iron oxides, and altered host rock

Quartz-veined metamorphic rock, likely greenschist or altered basalt

Chlorite–actinolite schist or metabasalt with a milky quartz vein

Pegmatitic mica–feldspar rock

Granitic pegmatite, composed chiefly of potassium feldspar, quartz, and biotite mica

Weathered granite boulder

Granite, a coarse-grained felsic intrusive igneous rock; likely quartz, feldspar, and mica

Weathered greenstone pebble

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

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

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

Tumbled jasper (likely yellow/brecciated jasper)

Microcrystalline quartz/chalcedony, SiO₂, with iron-oxide and clay inclusions

Polished jasper

Microcrystalline quartz (SiO₂), commonly with iron-oxide and clay inclusions

Polished orbicular jasper

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

Pink granite

Granite, a quartz–feldspar plutonic rock

Banded limestone or marble pebble

Calcite-rich carbonate rock; likely banded marble (CaCO₃)

Tumbled dark green beach pebble

Likely serpentinite or altered basalt; exact identification requires testing

Weathered brown rock, likely basalt or iron-rich breccia

Probable basaltic rock; exact identification is uncertain from the photograph

Likely weathered granite or granitic pebble

Granite; chiefly quartz, feldspar, and mica

Iron-stained quartz vein in altered host rock

Quartz (SiO₂) with iron oxides/hydroxides, likely hematite and goethite; host rock uncertain from the image

Dark mafic rock, likely altered basalt or gabbro

Fine- to medium-grained mafic silicate rock; probable basaltic composition with plagioclase and pyroxene, possibly chloritized/serpentinized

Weathered iron-rich rock (likely ironstone or altered basalt)

Probable limonite/goethite-bearing basalt or ironstone; exact identification requires testing

Orbicular granite (likely larvikite or related granitic rock)

Granite composed mainly of quartz, feldspar, and dark mafic minerals; exact variety is uncertain from the image

Weathered quartz-rich pebble, possibly metasandstone

Quartz-rich metasandstone (provisional); mainly SiO₂ with minor feldspar, mica, or iron oxides

Weathered granitic rock, possibly pegmatitic granite

Granite; chiefly quartz, feldspar, and mica (SiO₂-rich crystalline rock)

Weathered feldspathic rock, likely granite or granitic pegmatite

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

Iron-stained vesicular volcanic rock (probable basalt/scoria)

Altered basaltic scoria; chiefly plagioclase, pyroxene, olivine, and iron oxides

Tumbled granite or granitic pebble

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

Yellow serpentine (likely serpentine-rich rock)

Serpentinite; chiefly serpentine-group minerals, such as antigorite, lizardite, and chrysotile

Tumbled serpentine-rich rock

Serpentinite, likely antigorite/lizardite with magnetite and minor carbonates

Likely greenstone (serpentine or altered jade-like rock)

Serpentinite, chiefly serpentine-group minerals; exact identification requires testing

Weathered basalt (likely vesicular basalt)

Basalt; primarily plagioclase feldspar, pyroxene, and commonly olivine

Epidote

Epidote (Ca2(Al, Fe)3(SiO4)3(OH))

Tumbled greenstone (likely serpentinite or altered basalt)

Serpentinite, predominantly serpentine-group minerals; exact identification requires testing

Vesicular basalt with secondary zeolite/mineral crusts

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

Polished brecciated jasper

Jasper (microcrystalline quartz, SiO₂), likely brecciated and iron-oxide stained

Weathered basalt (likely altered basalt)

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

Weathered granite or granitic gneiss

Granite; chiefly quartz, feldspar, and mica

Weathered iron-rich basalt or volcanic scoria

Altered basalt, likely limonite/goethite-bearing (tentative)

Lapis Lazuli

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

Milky quartz vein rock

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

Weathered basaltic rock (probable vesicular basalt)

Basalt; primarily plagioclase feldspar, pyroxene, and commonly olivine, with iron-oxide alteration

Dumortierite Quartz

Aluminum Borate Silicate Oxide (Al7BO3(SiO4)3O3)