Metamorphic Or Igneous Alteration

Unakite

Altered Granite (Epidotized Granite)

Unakite

Granitic Unakite (Alteration rock composed of pink orthoclase feldspar, green epidote, and clear quartz)

Unakite-like granite

Altered granite, chiefly quartz, feldspar, mica, and red garnet

Unakite

Granite (altered hydrothermal)

Basalt with Epidote (Porphyry)

Basalt (with inclusions of Epidote/Feldspar)

Vesicular Basalt with Epidote

Vesicular Basalt (Mg, Fe)2SiO4 with Epidote (Ca2(Al2,Fe)(SiO4)(Si2O7)O(OH))

Weathered quartz-rich rock, likely quartzite or altered sandstone

Quartzite (mostly microcrystalline quartz, SiO₂); exact identification is uncertain from the photograph

Bronzite

Enstatite (var. Bronzite), (Mg,Fe)SiO3

Leopard-skin jasper (likely orbicular jasper)

Silicified volcanic rock, primarily microcrystalline quartz (SiO₂) with iron-oxide and dark mineral inclusions

Tumbled green stone, likely serpentine

Serpentinite; principally serpentine-group minerals, Mg₃Si₂O₅(OH)₄

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

Plutonic Igneous Rock (Granite)

Iron-rich basaltic pebble

Basalt, likely weathered and possibly ferruginous

Vesicular basalt (possibly scoriaceous basalt)

Basalt, chiefly plagioclase feldspar, clinopyroxene, and iron-titanium oxides

Weathered basalt (likely altered basalt)

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

Weathered basalt pebble

Basalt, a fine-grained mafic volcanic rock; likely olivine-bearing basalt

Rounded greenish river pebble, likely basalt or altered volcanic rock

Probable basalt (fine-grained mafic silicate rock), possibly epidote/chlorite-altered

Dark volcanic rock, likely basalt

Basalt; predominantly plagioclase feldspar, pyroxene, and minor olivine or magnetite

Basalt (Greenstone/Water-worn Pebble)

Basalt (containing Chlorite/Epidote)

Rhodonite

Rhodonite; (Mn,Fe,Mg,Ca)SiO3

Weathered iron-rich metamorphic rock, likely schist or quartzite

Provisional identification: ferruginous quartzite or mica schist; composition likely quartz (SiO₂), iron oxides/hydroxides, and mica or clay minerals

Greenstone (Celadonite-bearing Volcanic)

Hydrothermally altered basalt or andesite with Celadonite (K(Mg,Fe2+)(Fe3+,Al)Si4O10(OH)2)

Polished serpentine-rich stone (likely serpentine jasper or “rainforest jasper”)

Serpentine-group minerals, chiefly antigorite/lizardite, with iron oxides and silica-rich rock matrix

Pink granite (likely weathered pegmatitic granite)

Granite; chiefly quartz, potassium feldspar, plagioclase, and mica

Unakitized Granite

Granite / Altered Monzonite with Epidote

Epidote-bearing Granite (Unakite-like)

Epidotized Granite

Weathered porphyritic volcanic rock (likely basaltic andesite)

Porphyritic basaltic andesite; mineral assemblage likely plagioclase, pyroxene, and iron oxides

Tumbled pink feldspar-rich stone

Likely microcline feldspar (KAlSi₃O₈), possibly granite or quartz-feldspar pegmatite

Weathered iron-rich rock (likely basalt or ironstone)

Probable altered basalt; exact identification requires testing

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

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

Porphyritic volcanic rock, likely andesite

Porphyritic andesite; mainly plagioclase, pyroxene/amphibole, and volcanic groundmass

Granite Pebble (Unakite / Feldspar-rich Granite)

Granite (rich in Potassium Feldspar and Epidote)

Weathered basalt pebble

Basalt; fine-grained mafic volcanic rock, chiefly plagioclase and pyroxene with possible olivine

Tumbled dark igneous rock, likely basalt

Basalt; commonly composed of plagioclase feldspar, pyroxene, and olivine

Tumbled quartz-rich rock, likely quartzite or milky quartz with iron-oxide staining

Quartzite (primarily SiO₂), possibly with hematite/goethite staining and minor feldspar or mica

Translucent amber-colored gemstone, likely citrine or amber

Most plausibly quartz (SiO₂), specifically citrine; amber would be fossilized resin (organic polymer)

Weathered basalt pebble

Basalt, a fine-grained mafic volcanic rock composed mainly of plagioclase feldspar, pyroxene, and commonly olivine

Tumbled orbicular gabbro (likely oceanic gabbro)

Gabbro; chiefly plagioclase feldspar and pyroxene, with possible olivine, amphibole, and magnetite

Gabbroic or basaltic rock with weathered veins

Likely mafic igneous rock, possibly olivine gabbro or porphyritic basalt; exact identification requires testing

Granite

Granitic plutonic rock, chiefly quartz, alkali feldspar, plagioclase, and mica/amphibole

Rhyolite Cross Pendant

Rhyolite (High-silica volcanic rock)

Fine-grained mafic rock, likely basalt or altered basalt

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

Tumbled serpentinite (likely antigorite-rich serpentine)

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