Metamorphic (Altered Igneous Rock)

Unakite Jasper / Unakite

Altered Granite (containing Epidote, Orthoclase Feldspar, and Quartz)

Iron-rich vesicular rock, possibly weathered scoria or ironstone

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

Tumbled jasper, likely red/brown jasper

Microcrystalline quartz (chalcedony), SiO₂, colored by iron oxides

Granite pebble

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

Greenstone / Chert

Cryptocrystalline Quartz (SiO2) or Altered Basalt

Polished orbicular granite (likely larvikite or orbicular diorite)

Quartz/feldspar-bearing granitoid with dark amphibole–biotite minerals; exact variety requires testing

Lapis Lazuli

Lapis Lazuli (Complex rock consisting primarily of Lazurite (Na,Ca)8(AlSiO4)6(S,SO4,Cl)1-2)

Porphyritic basalt (likely amygdaloidal basalt)

Basaltic rock dominated by plagioclase feldspar and pyroxene, with possible vesicle-filling zeolite/calcite

Serpentinite

Serpentinite; chiefly serpentine-group minerals (antigorite, lizardite, chrysotile), with magnetite and minor chromite/talc

Lapis Lazuli

Lapis lazuli (a rock primarily composed of Lazurite: (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2)

Lapis Lazuli

Sodalite-rich metamorphic rock containing Lazurite (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2

Weathered granite pebble

Granite, predominantly quartz–feldspar–mica aggregate

Waterworn greenstone pebble

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

Smoky Quartz

Silicon Dioxide (SiO2)

Vesicular quartz-rich rock, possibly weathered rhyolite or silicified volcanic breccia

Silica-rich volcanic rock; likely microcrystalline quartz (SiO₂) with altered feldspar and iron-oxide staining

Weathered basalt (possibly iron-stained volcanic rock)

Basalt; predominantly plagioclase, pyroxene, and possibly olivine, with iron-oxide staining

Gold-bearing quartz vein rock (likely pyrite-rich quartzite)

Quartz (SiO₂) with iron sulfides, chiefly pyrite (FeS₂), possibly chalcopyrite (CuFeS₂); gold cannot be confirmed visually

Weathered porphyritic volcanic rock (likely andesite or basalt)

Porphyritic andesite/basalt; typically plagioclase feldspar ± pyroxene, olivine, and iron oxides

Iron-stained quartz-rich rock, likely pegmatite or quartz vein fragment

Quartz (SiO₂) with feldspar, mica, and iron-oxide/hydroxide staining; possibly weathered granite pegmatite

Rounded granitic pebble

Granite, chiefly quartz–feldspar–mica aggregate

Weathered volcanic rock, likely basalt

Basalt; primarily plagioclase feldspar, pyroxene, and often olivine

Serpentinized ultramafic rock (likely serpentinite)

Serpentinite; chiefly antigorite/lizardite/chrysotile, commonly after peridotite (olivine–pyroxene)

Greenstone / Basalt

Aphanitic Mafic Igneous Rock (likely altered Basalt)

Gray volcanic rock, likely basalt

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

Weathered basalt (likely)

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

Greenstone (Epidosite or Altered Basalt)

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

Biotite Mica

Biotite (K(Mg,Fe)3AlSi3O10(F,OH)2)

Rhodonite

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

Quartz-bearing greenstone (probable epidote–quartz rock)

Epidote–quartz schist/greenstone; chiefly quartz (SiO₂) and epidote [Ca₂(Al,Fe)₃(SiO₄)₃(OH)], with possible chlorite and feldspar

Conglomeratic or porphyritic basalt cobble

Likely vesicular basalt with weathered feldspar/mafic inclusions; exact identification requires testing

Rounded greenstone pebble

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

Lapis Lazuli

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

Red vesicular volcanic rock, likely scoria

Scoria (vesicular basalt/andesite), composition mainly plagioclase, pyroxene, iron oxides, and volcanic glass

Porphyritic basalt (likely vesicular basalt)

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

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

Tumbled greenstone (likely serpentinite or green jasper)

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

Pink-and-green granite or granitic gneiss

Coarse-grained granitoid, chiefly quartz, feldspar, and dark mafic minerals; pink areas likely potassium feldspar

Epidote (or Epidote-rich rock)

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

Propylitic Altered Andesite

Hydrothermally Altered Andesite

Biotite granite pebble

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

Unakite

Epidotized Granite (composition of Epidote, Orthoclase, and Quartz)