Metamorphic Or Igneous Alteration

Basalt with Epidote Veins

Mafic Igneous Rock (Basalt)

Celadonite in Amygdaloidal Basalt

K(Mg,Fe2+)(Fe3+,Al)Si4O10(OH)2 (Celadonite mineral) within a Basalt matrix

Sodalite

Sodalite (Na8(Al6Si6O24)Cl2)

Polished greenstone pebble (likely epidote-bearing stone)

Epidote–chlorite amphibolite or altered basalt; composition likely epidote, chlorite, amphibole/pyroxene, and iron oxides

Greenstone (likely serpentinite or chlorite-rich metamorphic rock)

Probable serpentinite/chlorite schist; commonly dominated by serpentine-group minerals, chlorite, talc, and magnetite

Waterworn greenstone pebble

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

Polished nephrite jade

Nephrite jade; compact amphibole aggregate, chiefly tremolite–actinolite, Ca₂(Mg,Fe)₅Si₈O₂₂(OH)₂

Likely polished green serpentine or aventurine

Serpentine-group minerals, commonly antigorite/lizardite; alternatively quartz-rich green aventurine

Serpentinite

Serpentinite (composed primarily of Serpentine group minerals such as Antigorite, Lizardite, and Chrysotile)

Charoite

Charoite (Hydrated potassium sodium calcium barium strontium silicate hydroxyfluoride)

Stichtite in Serpentine (Atlantisite)

Mg6Cr2CO3(OH)16·4H2O (Stichtite) within Mg3Si2O5(OH)4 (Serpentine)

Unakite or Red Jasper in Epidote

Unakite (Metasomatized Granite)

Feldspar in Matrix

Feldspar group minerals in metamorphic or igneous matrix

Tumbled orange-brown feldspathic rock, likely granite or weathered syenite

Feldspar-rich granitoid; chiefly K-feldspar and plagioclase with minor quartz and dark biotite/amphibole

Polished dark-green stone, likely serpentinite

Serpentinite; predominantly serpentine-group minerals, commonly antigorite, lizardite, or chrysotile, with possible magnetite and minor pyroxene

Tumbled tiger’s eye

Quartz (SiO₂) with fibrous riebeckite/crocidolite inclusions

Tiger’s eye

Quartz (SiO₂) with fibrous crocidolite pseudomorphs and iron oxides

Rhodonite

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

Serpentinite

Serpentinite (composed primarily of minerals in the serpentine group: (Mg,Fe,Ni,Al,Zn,Mn)2-3(Si,Al,Fe)2O5(OH)4)

Epidote (Unakite-related)

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

Serpentinite (probable)

Serpentinite, dominated by serpentine-group minerals (chrysotile, lizardite, or antigorite), commonly with magnetite

Tiger’s eye

Quartz variety, primarily silicon dioxide (SiO₂); fibrous quartz pseudomorph after crocidolite asbestos

Granite (with alteration)

Granite (Felsic intrusive igneous rock)

Greenstone / Basalt

Aphanitic Mafic Igneous Rock (likely altered Basalt)

Polished serpentine (likely bowenite)

Serpentine-group minerals, chiefly antigorite; bowenite is a nickel-rich translucent variety

Weathered serpentinite (likely serpentine-rich rock)

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

Tumbled nephrite jade (likely)

Nephrite jade; fibrous amphibole aggregate, chiefly actinolite–tremolite, Ca₂(Mg,Fe)₅Si₈O₂₂(OH)₂

Serpentine (likely serpentinized ultramafic rock)

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

Unakite

Altered Granite (composed of orthoclase feldspar, epidote, and quartz)

Unakite

Unakite (Epidotized Granite)

Greenstone / Serpentinite

Serpentinite (composed primarily of minerals from the serpentine group Mg3Si2O5(OH)4)

Red Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2 with Fe2O3 inclusions)

Stichtite in Serpentine (Atlantisite)

Mg6Cr2CO3(OH)16·4H2O (Stichtite) within Mg3Si2O5(OH)4 (Serpentine)

Weathered volcanic rock, likely andesite

Andesite (plagioclase–pyroxene volcanic rock), identification tentative

Rounded river pebble, likely basaltic or andesitic rock

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

Unakite

Altered Granite (Orthoclase Feldspar, Epidote, and Quartz)

Serpentine (Serpentinite)

Antigorite, Lizardite, or Chrysotile; (Mg,Fe)3Si2O5(OH)4

Serpentine (Serpentinite)

Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)2-3(Si, Al, Fe)2O5(OH)4

Serpentinite

Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)2-3(Si, Al, Fe)2O5(OH)4

Unakite

Epidotized Granite

Serpentinite pebble

Serpentinite, composed chiefly of serpentine-group minerals (lizardite, chrysotile, antigorite), with possible magnetite and chlorite

Polished jasper pebble

Jasper, microcrystalline quartz (SiO₂), commonly with iron-oxide impurities