Metamorphic (Altered Igneous Rock)

Tumbled basalt (likely vesicular basalt)

Basalt; primarily plagioclase, clinopyroxene, and olivine, with iron oxides

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

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

Weathered pink granite (probable)

Granite; quartz + feldspar + mica, with iron-oxide staining

Basalt in a vesicular volcanic host rock

Basalt, likely with secondary zeolite or calcite infill

Weathered granitic or feldspathic pebble

Likely granite/granodiorite; quartz–feldspar–mica aggregate

Quartz-rich pegmatite

Granitic pegmatite, chiefly quartz (SiO₂) with feldspar and possible mica

Weathered gray-green metamorphic pebble

Probable greenschist or chlorite-rich metavolcanic rock; exact identification requires testing

Weathered dark volcanic rock, possibly basalt

Basalt (tentative; likely iron-rich mafic volcanic rock)

Rounded yellow-green stone, likely serpentine or weathered greenstone

Serpentine-group minerals, commonly antigorite or lizardite; exact identification requires testing

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

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

Rounded dark pebble, likely basaltic andesite

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

Polished basalt pebble

Basalt; primarily plagioclase feldspar, pyroxene, and commonly olivine or iron oxides

Weathered iron-rich rock with quartz/calcite veining

Likely ironstone or ferruginous quartzite; white material may be quartz or calcite

Weathered porphyritic volcanic rock, likely rhyolite or andesite

Porphyritic rhyolite–andesite; mainly quartz/feldspar phenocrysts in a fine iron-stained groundmass

Chlorite-rich metamorphic rock, likely greenschist

Greenschist; commonly composed of chlorite, actinolite, epidote, albite, and quartz

Rhodonite

Rhodonite, manganese inosilicate — MnSiO₃; the specimen may include quartz, feldspar, and black manganese-oxide minerals in the matrix

Weathered volcanic rock, likely andesite

Porphyritic andesite (tentative; image alone cannot confirm composition)

Tumbled black tourmaline

Schorl tourmaline, NaFe²⁺₃Al₆(BO₃)₃Si₆O₁₈(OH)₄

Tumbled serpentine

Serpentine-group minerals, chiefly antigorite, lizardite, or chrysotile; approximate formula Mg₃Si₂O₅(OH)₄

Tumbled pink feldspar or rhodonite-like stone

Most likely potassium feldspar (orthoclase/microcline), KAlSi₃O₈; possibly rhodonite, MnSiO₃

Weathered gray-green volcanic rock

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

Mixed tumbled river pebbles and beach stones

Polymictic alluvial gravel; components include quartz, chert, jasper, sandstone, and altered volcanic rocks

Iron-rich vesicular rock, possibly weathered scoria or ironstone

Likely oxidized basaltic scoria (Fe-oxide-bearing volcanic rock); exact identification requires testing

Rounded gray-green metamorphic rock, likely serpentinite

Serpentinite; primarily serpentine-group minerals (lizardite/chrysotile/antigorite), commonly with magnetite and minor carbonate

Basaltic beach cobble

Fine- to medium-grained basalt, likely locally porphyritic or altered

Weathered basalt pebble (likely vesicular basalt)

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

Serpentine (Healerite variety)

Serpentine group, Mg3Si2O5(OH)4

New Jade (Serpentine)

Antigorite / Serpentine group (Mg3Si2O5(OH)4)

Tiger's Eye

Silicon dioxide (SiO2) with fibrous inclusions of crocidolite

Weathered iron-rich basalt or volcanic breccia

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

Polished/tumbled unakite (probable)

Unakite; epidote + pink potassium feldspar + quartz

Granite (likely weathered, pegmatitic granite)

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

Polished tiger iron

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

Vuggy quartz-rich breccia

Silicified volcanic or hydrothermal breccia; mainly microcrystalline quartz (SiO₂), with possible calcite and iron-oxide minerals

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

Likely serpentine or serpentine-rich stone

Serpentine-group minerals, chiefly antigorite/lizardite; approximate formula Mg₃Si₂O₅(OH)₄

Quartz vein in foliated metamorphic rock

Milky quartz (SiO₂) in likely schist or gneiss

Weathered granite or granitic gneiss fragment

Granite; chiefly quartz (SiO₂), feldspar, and mica

Weathered quartz-rich rock, possibly milky quartz in altered host rock

Milky quartz (SiO₂), with probable iron-oxide staining and a fine-grained host matrix

Serpentinite (likely serpentinized ultramafic rock)

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

Serpentine-rich greenstone (probable serpentinized rock)

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

Chrysoprase-bearing serpentinite (probable)

Serpentinized ultramafic rock; chiefly serpentine-group minerals, with possible chrysoprase (nickel-bearing chalcedony) and magnesite